mediatechnology said:Hey all would've jumped back in sooner bit for some reason topic reply notification stops working sometimes...(even though I do click on the e-mail links consistently)
Thank goodness!
Yes. I've installed a Hubbelll Twist lock 220 volt female and I'm plugging in the power transformer leg-leg right there. There's both phases and a ground, NO NEUTRAL. Repeat, NO NEUTRAL.
I'm the "electrician"! I ran that to a two pole breaker in the breaker box. I'm putting in a fuse on the Iso transformer because the smallest breaker I could find was 15 amps 220 volts. So I'm putting in a 10 amp slow blow fuse on the primary of the iso transformer. I get real confused by concepts of volt-amps versus watts, so that was just a pie in the sky judgment on my part, so what do you think? (It's a 2.5 kva transformer).
I'm no Jimmy Page but I do know how to kill a breaker.
Studio Electrical Discussion from Utility to Outlet deleted
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SSLtech
Well-known member
[quote author="bobkatz"]It's proper shielding, not grounding, that prevents RFI.[/quote]
AFL. (that's "Abso-flippin'-lutely", not "after-fade-listen"! :wink: )
However, a shield is SO much more effective if it "bleeds" the interference by draining it to common.
In Britain, hums are sometimes VERY difficult to get rid of, because of the "ring main" wiring approach, which is mandated by British Standard number 1363 (I think that's accurate...) Anyhow, current flows (shared variably and unpredictably) through a ring that usually encircles the room... -Inductive loop, anyone?
Anyhow, that's a clue: inductive.
Inductive loops of that type tend to be more efficient at lower frequencies... which is actually a bit of a nuisance, seeing as how AC power is at a nice low frequency. -Bugger. Hello 50Hz hum, and "can I have a 'G' please Bob?" -Oh, and shielding does 9-parts-of-bugger-all to fix that problem... -Good thing that it's much less common in the US! -Oh, and since most houses are also brick-and-plaster construction, and were built before electrickery was available to the unwashed masses (my last house in Britain was built in the 18th century...) there's no pipes to pull wires through. -As a consequence, the electrical regulations allow for 3-conductor 240V, PVC-insulated power cables to be buried just beneath the wall surface. No metal conduit. No shielding. -Just a nice ring of wire around the room(s).
RFI is by its nature is mercifully easier to deal with, and that suits me well in my encounters with installations in the USA, because I find less persistently annoying 'magnetic' low-frequency hum problems in the USA than I did in the UK. Shielding works beautifully for radio frequency problems. EMI is rather less well taken care of by a foil shield than RFI is...
When I reflect upon it, the US practice -presumably mandated in the NEC- of grounded romex or grounded conduit surrounding all the current-bearing conductors probably does nothing but good, and the "home-run" approach over the "ring-and-spur" method means that I don't think I ever encounter the sort of 'incurable' hums that I used to.
Keith
AFL. (that's "Abso-flippin'-lutely", not "after-fade-listen"! :wink: )
However, a shield is SO much more effective if it "bleeds" the interference by draining it to common.
In Britain, hums are sometimes VERY difficult to get rid of, because of the "ring main" wiring approach, which is mandated by British Standard number 1363 (I think that's accurate...) Anyhow, current flows (shared variably and unpredictably) through a ring that usually encircles the room... -Inductive loop, anyone?
Anyhow, that's a clue: inductive.
Inductive loops of that type tend to be more efficient at lower frequencies... which is actually a bit of a nuisance, seeing as how AC power is at a nice low frequency. -Bugger. Hello 50Hz hum, and "can I have a 'G' please Bob?" -Oh, and shielding does 9-parts-of-bugger-all to fix that problem... -Good thing that it's much less common in the US! -Oh, and since most houses are also brick-and-plaster construction, and were built before electrickery was available to the unwashed masses (my last house in Britain was built in the 18th century...) there's no pipes to pull wires through. -As a consequence, the electrical regulations allow for 3-conductor 240V, PVC-insulated power cables to be buried just beneath the wall surface. No metal conduit. No shielding. -Just a nice ring of wire around the room(s).
RFI is by its nature is mercifully easier to deal with, and that suits me well in my encounters with installations in the USA, because I find less persistently annoying 'magnetic' low-frequency hum problems in the USA than I did in the UK. Shielding works beautifully for radio frequency problems. EMI is rather less well taken care of by a foil shield than RFI is...
When I reflect upon it, the US practice -presumably mandated in the NEC- of grounded romex or grounded conduit surrounding all the current-bearing conductors probably does nothing but good, and the "home-run" approach over the "ring-and-spur" method means that I don't think I ever encounter the sort of 'incurable' hums that I used to.
Keith
[quote author="SSLtech"][quote author="bobkatz"]It's proper shielding, not grounding, that prevents RFI.[/quote]
AFL. (that's "Abso-flippin'-lutely", not "after-fade-listen"! :wink: )
However, a shield is SO much more effective if it "bleeds" the interference by draining it to common.
[/quote]
That common can and should be the chassis of the equipment inside, whether or not it is floating at 1000 volts to "true ground". To prevent RFI in the highest RF environment in the world on the 103rd floor of the bulding, I removed the XLR male connector of the mike and through a very small hole into the preamp chassis I soldered the braid to the chassis there. 90 dB SNR in an instant.
Now that is a real problem for single coil pickups!
pull wires through. -As a consequence, the electrical regulations allow for 3-conductor 240V, PVC-insulated power cables to be buried just beneath the wall surface. No metal conduit. No shielding. -Just a nice ring of wire around the room(s).
[/quote]
PVC is most common here. Do they still run EMT in office buldings in the U.S?
AFL. (that's "Abso-flippin'-lutely", not "after-fade-listen"! :wink: )
However, a shield is SO much more effective if it "bleeds" the interference by draining it to common.
[/quote]
That common can and should be the chassis of the equipment inside, whether or not it is floating at 1000 volts to "true ground". To prevent RFI in the highest RF environment in the world on the 103rd floor of the bulding, I removed the XLR male connector of the mike and through a very small hole into the preamp chassis I soldered the braid to the chassis there. 90 dB SNR in an instant.
Now that is a real problem for single coil pickups!
pull wires through. -As a consequence, the electrical regulations allow for 3-conductor 240V, PVC-insulated power cables to be buried just beneath the wall surface. No metal conduit. No shielding. -Just a nice ring of wire around the room(s).
[/quote]
PVC is most common here. Do they still run EMT in office buldings in the U.S?
SSLtech
Well-known member
Ah... you mean PVC tubing for domestic jobs? -Didn't know that.
All of my interactions with electricians are in connection with commercial installaions, and they ALWAYS use romex & metal pipe. -I'd assumed that it was applicable for both.
Keith
All of my interactions with electricians are in connection with commercial installaions, and they ALWAYS use romex & metal pipe. -I'd assumed that it was applicable for both.
Keith
[quote author="mediatechnology"]Bob sounds like it's moving along for you. One of the reasons the NEC allows hospital surgical suites to ground the way they do is that they don't want the patient connected to the building when it's being hit by lightning. (Jeeze - you think the patient shouldn't be connected to the building's lightning arrestors?) Another driven rod not connected to the other ones couldn't hurt I don't think. The hospital problem is the same as yours.
[/quote]
I heard that it is illegal (not according to the NEC) to have more than one ground. Could you elaborate what's legal in surgical suites? Can I legally run a separate, isolated, insulated ground to the chassis of the Iso transformer and thence to the electrical system of the mastering room?
RF line? What do you mean? The reason this house is so susceptible to lightning issues is the extreme long ethernet lines just get such a high difference of potential in the presence of lightning strikes. You power one computer in one room on one outlet and 150 feet away another on another power outlet and also run ethernet and that creates a tremendous potential difference. I also blew out THREE Panasonic telephone controllers and gave up on them and went to a wireless telephone system. Florida is the lightning capital of the world.
By the way, I'm going to go with single phase on the secondary because I don't want to buy two $366 Surge-X outlet boxes when one will do.
[/quote]
I heard that it is illegal (not according to the NEC) to have more than one ground. Could you elaborate what's legal in surgical suites? Can I legally run a separate, isolated, insulated ground to the chassis of the Iso transformer and thence to the electrical system of the mastering room?
RF line? What do you mean? The reason this house is so susceptible to lightning issues is the extreme long ethernet lines just get such a high difference of potential in the presence of lightning strikes. You power one computer in one room on one outlet and 150 feet away another on another power outlet and also run ethernet and that creates a tremendous potential difference. I also blew out THREE Panasonic telephone controllers and gave up on them and went to a wireless telephone system. Florida is the lightning capital of the world.
By the way, I'm going to go with single phase on the secondary because I don't want to buy two $366 Surge-X outlet boxes when one will do.
Hi, Wayne. So you've been around. Next time you're in Orlando, come visit and listen to some of the finest audio monitoring in Florida or anywhere! Parc studios, eh. I think they just closed.
[quote author="mediatechnology"]Bob, I understand the potential differences on the ethernet lines within the building. But, if you are connected to a cable modem, there may be a path from the cable system's lightning arrestor into your tech facility. Ethernet is almost always transformer isolated but sparks can still jump as you know.
[/quote]
Right, and even with transformer isolated at high frequencies with these tiny one winding transformers, with lightning-sized spikes we're done for. If I had not found these Ethernet surge protectors I would have had to invent an optical solution! Basically, the cable modem is the only thing connected to the cable ground, EXCEPT for that inductive impedance at lightning frequencies that certainly makes it through any copper that uses a little tiny Ethenet transformer.
It's good to know about the ground and your knowledge of the code. Someday I plan on putting another isolation transformer to feed Studio A, and grounding it to a spike right outside the studio wall.
Currently the cable system is not connected to our audio system, only through ethernet to my router. But it's those long lines that create the imbalance that causes the thing to fail. Each box is locallly grounded through the U-ground and the lightning-based potential just creates this big difference of potential to any local ground----that high potential damages the Ethernet port despite the transformer coupling you say there is. And the existence of that surge at that particular location is provable because as soon as attach the surge protector to drain the ethernet wires through the Furst protector to the chassis of any router or computer, there are no more problems. I have many short run ethernet cables within a given office that do not have the surge protectors that have no problems. So, basically where the problems develop are where the long lines come into the Ethernet switches. I've gone into some Ethernet switches that do not have ground terminals and soldered a ground wire there to the PC board ground, and that works.
As for the cable ground, right now we're not viewing cable (the video portion) in the audio studio, but when I decide to connect the cable system into our audio systems I'll buy a Jensen high bandwidth video isolation transformer so the cable system ground does not touch our audio ground. That's more for hum-prevention than lightning issues, but I hope it doesn't cause any lightning-based issues! And I hope it passes the digital cable!
I connected the Topaz electrostatic shields to its chassis and the chassis to our house "dirty ground". (Dirty in the sense it touches neutral before it makes it out to the earth). It's the best I can do short of EXTREME expense bringing in a new heavy duty clean ground.
Anything else I haven't thought of?
[quote author="mediatechnology"]Bob, I understand the potential differences on the ethernet lines within the building. But, if you are connected to a cable modem, there may be a path from the cable system's lightning arrestor into your tech facility. Ethernet is almost always transformer isolated but sparks can still jump as you know.
[/quote]
Right, and even with transformer isolated at high frequencies with these tiny one winding transformers, with lightning-sized spikes we're done for. If I had not found these Ethernet surge protectors I would have had to invent an optical solution! Basically, the cable modem is the only thing connected to the cable ground, EXCEPT for that inductive impedance at lightning frequencies that certainly makes it through any copper that uses a little tiny Ethenet transformer.
It's good to know about the ground and your knowledge of the code. Someday I plan on putting another isolation transformer to feed Studio A, and grounding it to a spike right outside the studio wall.
Currently the cable system is not connected to our audio system, only through ethernet to my router. But it's those long lines that create the imbalance that causes the thing to fail. Each box is locallly grounded through the U-ground and the lightning-based potential just creates this big difference of potential to any local ground----that high potential damages the Ethernet port despite the transformer coupling you say there is. And the existence of that surge at that particular location is provable because as soon as attach the surge protector to drain the ethernet wires through the Furst protector to the chassis of any router or computer, there are no more problems. I have many short run ethernet cables within a given office that do not have the surge protectors that have no problems. So, basically where the problems develop are where the long lines come into the Ethernet switches. I've gone into some Ethernet switches that do not have ground terminals and soldered a ground wire there to the PC board ground, and that works.
As for the cable ground, right now we're not viewing cable (the video portion) in the audio studio, but when I decide to connect the cable system into our audio systems I'll buy a Jensen high bandwidth video isolation transformer so the cable system ground does not touch our audio ground. That's more for hum-prevention than lightning issues, but I hope it doesn't cause any lightning-based issues! And I hope it passes the digital cable!
I connected the Topaz electrostatic shields to its chassis and the chassis to our house "dirty ground". (Dirty in the sense it touches neutral before it makes it out to the earth). It's the best I can do short of EXTREME expense bringing in a new heavy duty clean ground.
Anything else I haven't thought of?
SSLtech
Well-known member
[quote author="bobkatz"]Parc studios, eh. I think they just closed.[/quote]
Nope, just changed hands. The new owner has invited our venerable mutual acquaintance Andy 'D' over for a last farewell the day after tomorrow. (Andy is leaving town as you may know.) -Actually, mediatechnology, (is it Wayne?) if you commissioned the PARC console you would probably be familiar with Andy yourself: He was the house engineer there 'back in the day'.
Andy speaks in reverent, hushed tones of Mr. Katz, and is a good friend, and the former owner from new of my most recent car purchase as it happens...
The wording may do little to discourage ambiguity, but I understand it to mean that you cannot have more than one SEPERATE ground. You can have as many grounds as you like, as long as they're all connected (is that a self-defeating description?) -I believe that what you're describing may fail the test of having copper continuity from the third pin of the power outlets all the way back to the power company's NEC-approved & declared-safe ground.
...on the other hand I may be imagining that requirement...
Bob, I didn't know that you had a sports team in N.Carolina named after you... -I AM impressed! :green:
Keith
Nope, just changed hands. The new owner has invited our venerable mutual acquaintance Andy 'D' over for a last farewell the day after tomorrow. (Andy is leaving town as you may know.) -Actually, mediatechnology, (is it Wayne?) if you commissioned the PARC console you would probably be familiar with Andy yourself: He was the house engineer there 'back in the day'.
Andy speaks in reverent, hushed tones of Mr. Katz, and is a good friend, and the former owner from new of my most recent car purchase as it happens...
The wording may do little to discourage ambiguity, but I understand it to mean that you cannot have more than one SEPERATE ground. You can have as many grounds as you like, as long as they're all connected (is that a self-defeating description?) -I believe that what you're describing may fail the test of having copper continuity from the third pin of the power outlets all the way back to the power company's NEC-approved & declared-safe ground.
...on the other hand I may be imagining that requirement...
Bob, I didn't know that you had a sports team in N.Carolina named after you... -I AM impressed! :green:
Keith
SSLtech
Well-known member
[quote author="mediatechnology"]Tell him hello.[/quote]
You tell him! -Come down on Friday... you, me, Bob, Andy... Sounds like a reason to lock up my credit card! :wink:
[quote author="mediatechnology"]After Bob told me he scored the Topaz I again thought about Skycraft[/quote]
You know, I did wonder how you knew where Bob had scored it... he never mentioned it in the thread, and I assumed you'd corresponded vie email or something... -well now I know how enlightened you really ARE!
In the '90's... he'd have been driving this ... now it's Mine... all MINE!!! Muahahahaaaaaa!!!!
:green:
Keef
You tell him! -Come down on Friday... you, me, Bob, Andy... Sounds like a reason to lock up my credit card! :wink:
[quote author="mediatechnology"]After Bob told me he scored the Topaz I again thought about Skycraft[/quote]
You know, I did wonder how you knew where Bob had scored it... he never mentioned it in the thread, and I assumed you'd corresponded vie email or something... -well now I know how enlightened you really ARE!
In the '90's... he'd have been driving this ... now it's Mine... all MINE!!! Muahahahaaaaaa!!!!
:green:
Keef
> the "ring main" wiring approach, which is mandated by British Standard number...
I have a 1938 UK wiring manual, and there is NO hint of Ring Main inside the premises. (They do show one connecting several sub-stations.)
> electrical regulations allow for 3-conductor 240V, PVC-insulated power cables to be buried just beneath the wall surface.
And worse. Like rubber insulated cable. Remember: 1938. No modern Neoprene or other synthetic polymers, just tree-sap cooked with a little Sulphur.
> the US practice -presumably mandated in the NEC- of grounded romex or grounded conduit
Never been mandated by NEC. By the time knob-and-tube (open) wiring was going out of style, various NMC (non-metallic cable) systems were available.
NEC does require conduit where the wiring may be damaged. But aside from special cases like gasoline stations and mines, it does not say what risk of "damage" requires conduit. That is left to the Local Authority. (We must note that the NEC has no authority; it is just a convenient foundation for Local Authority to adopt and adapt to local conditions.)
In my school, ALL wiring is conduit. Won't even use 3 feet of metal-flex, just the 18" that the NEC suggests for connecting to motors and lamps that might move. My observation is that most commercial work around here is also in conduit. Residential work is NEVER in conduit around here, it is all NMC: two insulated wires plus a ground enclosed in a PVC jacket.
I have heard that in certain cities, full metal conduit is required for all electricity. This may be extreme fire prevention in densely-packed residential areas, rather than job-protection for the Electrician's Union as some people think.
> you mean PVC tubing for domestic jobs?
There is a grey plastic tubing widely used for outdoor runs where plain NMC is not a good idea. When used with its glued couplings and gasketed boxes, it is mighty close to water-tight, more so than simple EMT (light metal tubing with pinch-screw or compression joints). It isn't as solid as true screwed conduit, but it is a heck of a lot easier to work with.
I should think that an inside run in low-density Florida would be plain NMC fished through walls or in plastic WireMold. No metallic shield, but the cable can be had Twisted or untwisted. To comply with the White=GroundED rule, a 240V-only run probably should be wired with 3G cable: White-Black-Red-Green, with the White ignored if not needed. That's wasteful, but using the White in 2G white-Black-Green cable as a Hot is bad form. (Yes, you can permanently un-White it and use it as Hot.) And 3G cable is usually Twisted, while 2G cable is often "twinlead" with no twist except whatever you get by pulling it out the inside of the reel. The 70-foot run of 3G cable that I ran to my stove was not expensive compared to my labor. And that cable was rated 45 Amps peak (only for stove duty, I think 30A for general duty, which is more than Bob needs.)
Stove-cable is probably good. Not that this 11-amp load needs 30 Amp cable, but the wire must be fused and as you know it is hard to find double-pole breakers smaller than 20A or 30A. Also you want a FAT ground wire. Note that large-gauge cable often has Ground one gauge smaller than the hot wires, so you may need "overkill" for a fat ground. Upstairs, you might want a 10A or 15A slo-blo fuse to protect the transformer, though unless you run A/C off this tranny I doubt you would ever pull 2,500 Watts of load without noticing HEAT. (That's like two electric room-heaters.)
I used to lose a modem and an answering machine every summer, from lightning. The house once had overhead phone and power lines. When they split the lot, they put in new underground services to each sublot, so I had underground power and six underground phone lines. BUT they never cut-over the phone service and it still came in the overhead line. So the overhead line caught lightning, which headed toward the grounded electric service. But the phone protector was grounded to the water pipes, and they had installed a plastic water line up to the house. So I had 6 inches of dry dirt as phone "ground". The "best" path for lightning was through the modem, and when that zapped the next-best was the answering machine.
Finally it ruined the 1930s heavy-porcelain carbon-block protector so bad that I could not hold the line. Got a guy out, and told him that this overhead line was stupid when I had 6 underground lines. He went beyond the call of duty and cut my line over to underground, and took the overhead line away. That modem lasted five summers, and was retired only because I got DSL.
As Bob says, the loop-area between the audio (phone) and power may matter. I had a 20'x100' loop, reduced to a 3'x100' loop plus dirt shielding, and it made a difference.
> Dirty in the sense it touches neutral before it makes it out to the earth
That's Required. All Whites and all Grounds connect at the Main Entrance(*). Not upstairs in the sub-panel! And you can't go from studio, to dirt-rod, to Main Service: it must run studio to Main Service to Dirt.
Dirt in Florida is useless. Damp enuff but pure sand. Bond to it to reduce outdoor shocks, but you won't get enough ground to swallow lightning. A large metal piping system would be good, but has been rare for decades. Even my gas comes in via plastic. Unless you can bury a couple of Cadillacs, salt the earth, and wet it in dry months, you are just sitting on damp powdered glass.
(*) Exception: with a true transformer you have a Separately Derived Source. You can bond all your studio Whites and Grounds in that distribution box, and run one Ground wire back to the White+Ground bus in the Main Entrance.
But DANGIT... go to the library, they have the NEC in the Reference section. Or go buy a copy.... I get a new one every decade or so, even though my house is still catching-up with the 1950s. And get an Annotated edition. The actual NEC assumes a lot of jargon, you need interpretation and context. I like McPartland NEC Handbook, McGraw-Hill. The 2005 edition is ISBN: 0071443401 Amazon.com has it at $60, or $122 with NFPA's annotated NEC ISBN: 0877656231 (a good pair); both are available for less via used-book sites, especially if you take a 2002 edition (basics change slowly, though for swimming-pools and hot-tubs you MUST be up-to-date).
I have a 1938 UK wiring manual, and there is NO hint of Ring Main inside the premises. (They do show one connecting several sub-stations.)
> electrical regulations allow for 3-conductor 240V, PVC-insulated power cables to be buried just beneath the wall surface.
And worse. Like rubber insulated cable. Remember: 1938. No modern Neoprene or other synthetic polymers, just tree-sap cooked with a little Sulphur.
> the US practice -presumably mandated in the NEC- of grounded romex or grounded conduit
Never been mandated by NEC. By the time knob-and-tube (open) wiring was going out of style, various NMC (non-metallic cable) systems were available.
NEC does require conduit where the wiring may be damaged. But aside from special cases like gasoline stations and mines, it does not say what risk of "damage" requires conduit. That is left to the Local Authority. (We must note that the NEC has no authority; it is just a convenient foundation for Local Authority to adopt and adapt to local conditions.)
In my school, ALL wiring is conduit. Won't even use 3 feet of metal-flex, just the 18" that the NEC suggests for connecting to motors and lamps that might move. My observation is that most commercial work around here is also in conduit. Residential work is NEVER in conduit around here, it is all NMC: two insulated wires plus a ground enclosed in a PVC jacket.
I have heard that in certain cities, full metal conduit is required for all electricity. This may be extreme fire prevention in densely-packed residential areas, rather than job-protection for the Electrician's Union as some people think.
> you mean PVC tubing for domestic jobs?
There is a grey plastic tubing widely used for outdoor runs where plain NMC is not a good idea. When used with its glued couplings and gasketed boxes, it is mighty close to water-tight, more so than simple EMT (light metal tubing with pinch-screw or compression joints). It isn't as solid as true screwed conduit, but it is a heck of a lot easier to work with.
I should think that an inside run in low-density Florida would be plain NMC fished through walls or in plastic WireMold. No metallic shield, but the cable can be had Twisted or untwisted. To comply with the White=GroundED rule, a 240V-only run probably should be wired with 3G cable: White-Black-Red-Green, with the White ignored if not needed. That's wasteful, but using the White in 2G white-Black-Green cable as a Hot is bad form. (Yes, you can permanently un-White it and use it as Hot.) And 3G cable is usually Twisted, while 2G cable is often "twinlead" with no twist except whatever you get by pulling it out the inside of the reel. The 70-foot run of 3G cable that I ran to my stove was not expensive compared to my labor. And that cable was rated 45 Amps peak (only for stove duty, I think 30A for general duty, which is more than Bob needs.)
Stove-cable is probably good. Not that this 11-amp load needs 30 Amp cable, but the wire must be fused and as you know it is hard to find double-pole breakers smaller than 20A or 30A. Also you want a FAT ground wire. Note that large-gauge cable often has Ground one gauge smaller than the hot wires, so you may need "overkill" for a fat ground. Upstairs, you might want a 10A or 15A slo-blo fuse to protect the transformer, though unless you run A/C off this tranny I doubt you would ever pull 2,500 Watts of load without noticing HEAT. (That's like two electric room-heaters.)
I used to lose a modem and an answering machine every summer, from lightning. The house once had overhead phone and power lines. When they split the lot, they put in new underground services to each sublot, so I had underground power and six underground phone lines. BUT they never cut-over the phone service and it still came in the overhead line. So the overhead line caught lightning, which headed toward the grounded electric service. But the phone protector was grounded to the water pipes, and they had installed a plastic water line up to the house. So I had 6 inches of dry dirt as phone "ground". The "best" path for lightning was through the modem, and when that zapped the next-best was the answering machine.
Finally it ruined the 1930s heavy-porcelain carbon-block protector so bad that I could not hold the line. Got a guy out, and told him that this overhead line was stupid when I had 6 underground lines. He went beyond the call of duty and cut my line over to underground, and took the overhead line away. That modem lasted five summers, and was retired only because I got DSL.
As Bob says, the loop-area between the audio (phone) and power may matter. I had a 20'x100' loop, reduced to a 3'x100' loop plus dirt shielding, and it made a difference.
> Dirty in the sense it touches neutral before it makes it out to the earth
That's Required. All Whites and all Grounds connect at the Main Entrance(*). Not upstairs in the sub-panel! And you can't go from studio, to dirt-rod, to Main Service: it must run studio to Main Service to Dirt.
Dirt in Florida is useless. Damp enuff but pure sand. Bond to it to reduce outdoor shocks, but you won't get enough ground to swallow lightning. A large metal piping system would be good, but has been rare for decades. Even my gas comes in via plastic. Unless you can bury a couple of Cadillacs, salt the earth, and wet it in dry months, you are just sitting on damp powdered glass.
(*) Exception: with a true transformer you have a Separately Derived Source. You can bond all your studio Whites and Grounds in that distribution box, and run one Ground wire back to the White+Ground bus in the Main Entrance.
But DANGIT... go to the library, they have the NEC in the Reference section. Or go buy a copy.... I get a new one every decade or so, even though my house is still catching-up with the 1950s. And get an Annotated edition. The actual NEC assumes a lot of jargon, you need interpretation and context. I like McPartland NEC Handbook, McGraw-Hill. The 2005 edition is ISBN: 0071443401 Amazon.com has it at $60, or $122 with NFPA's annotated NEC ISBN: 0877656231 (a good pair); both are available for less via used-book sites, especially if you take a 2002 edition (basics change slowly, though for swimming-pools and hot-tubs you MUST be up-to-date).
[quote author="mediatechnology"]Bob;
Just found this reference:
http://omegaps.com/Lightning%20Guide_FINALpublishedversion_May051.pdf
Haven't had a chance to read it yet. Looks interesting.
[/quote]
Thanks, Wayne. I just read it. It's very comprehensive. My biggest concerns at this point are the ethernet cables where the long cables pick up the potential from the lightning strikes. My practice has been to put protectors on each ethernet port at the backbone (the main switch) and at any Ethernet ports that are connected through more than about 20' of cable.
But that document reminds me I need to protect the cable system where it enters my cable distribution amplifier, and each TV set or receiver as well. So, it's out to get those "multiport protectors".
On the day I install the cable system in the mastering room (no rush for that, we do not have video in there), my plan is to install a Jensen to avoid hum loops, and a multiport protector (bonded to the U ground) on the SECONDARY of the Jensen. Do you suppose it will create hum loops if I bond the primary of the Jensen to U-Ground through a separate multiport protector? I think that would defeat the purpose of the isolation transformer.
Just found this reference:
http://omegaps.com/Lightning%20Guide_FINALpublishedversion_May051.pdf
Haven't had a chance to read it yet. Looks interesting.
[/quote]
Thanks, Wayne. I just read it. It's very comprehensive. My biggest concerns at this point are the ethernet cables where the long cables pick up the potential from the lightning strikes. My practice has been to put protectors on each ethernet port at the backbone (the main switch) and at any Ethernet ports that are connected through more than about 20' of cable.
But that document reminds me I need to protect the cable system where it enters my cable distribution amplifier, and each TV set or receiver as well. So, it's out to get those "multiport protectors".
On the day I install the cable system in the mastering room (no rush for that, we do not have video in there), my plan is to install a Jensen to avoid hum loops, and a multiport protector (bonded to the U ground) on the SECONDARY of the Jensen. Do you suppose it will create hum loops if I bond the primary of the Jensen to U-Ground through a separate multiport protector? I think that would defeat the purpose of the isolation transformer.
This has been a great discussion. Sorry to open up an old question again.
If the answer to this question is "yes" it could cost me about $1000!
I just realized that if I split the secondaries of my Topaz (use 2 phase in Studio B) I'm going to have to get TWO Surge-X SA-20 (or SA-15) surge protectors and a second UPS. Instead of only ONE of each.
The reason I had been contemplating 2-phase has been that perhaps I'll get some isolation between power line noise generated by computers and sensitive analog ampliifiers if I put the computers on one phase and the sensitive (high gain, in general) analog gear on the other. Has anyone had any practical experience with isolation transformers to say if the split winding offers any isolation of that sort? After all, both hots still have a center tap which is a common neutral at that point (also bonded to ground).
BK
If the answer to this question is "yes" it could cost me about $1000!
I just realized that if I split the secondaries of my Topaz (use 2 phase in Studio B) I'm going to have to get TWO Surge-X SA-20 (or SA-15) surge protectors and a second UPS. Instead of only ONE of each.
The reason I had been contemplating 2-phase has been that perhaps I'll get some isolation between power line noise generated by computers and sensitive analog ampliifiers if I put the computers on one phase and the sensitive (high gain, in general) analog gear on the other. Has anyone had any practical experience with isolation transformers to say if the split winding offers any isolation of that sort? After all, both hots still have a center tap which is a common neutral at that point (also bonded to ground).
BK
SSLtech
Well-known member
Bob,
Some food for thought to consider alongside Wayne's points:
I think the first time you and I ever met was outside the computer and I/O racks for the Neve Capricorn install. In that instance, I'd specified a 2x120V output (240V-split) from a full-time-online UPS, and it had to run power to the control surface through the same (wide) pipe that all of the audio lines went through, from the I/O's to the patchbay in the control room.
The console was run on 240V line-to-line, and was a series of switching supoplies, each supply taking care of one small area of the control surface.
I ran the power line down the same tube right next to the audio snakes, but I did so down "3-wire-plus-shield" power cable, which also had a 'slow twist' to the three conductors inside the shield.
From that one installlation I can say that my fears about noise hopping from power to audio turned out to be unfounded. -I really did expect some sort of probelm to solve, but even with the UPS running, we never had any buzz or nastiness, over something like a 45-50 foot adjacent span.
-Of course in addition to the power source being 'balanced', the audio lines were the original Neve design inputs & outputs, and they were not too shabby at rejecting stuff, but I do have to confess, I was mightily relieved that there were no problems whatsoever... -If the truth be told, I don't think I had a fallback plan! :shock: :wink:
Keith
Some food for thought to consider alongside Wayne's points:
I think the first time you and I ever met was outside the computer and I/O racks for the Neve Capricorn install. In that instance, I'd specified a 2x120V output (240V-split) from a full-time-online UPS, and it had to run power to the control surface through the same (wide) pipe that all of the audio lines went through, from the I/O's to the patchbay in the control room.
The console was run on 240V line-to-line, and was a series of switching supoplies, each supply taking care of one small area of the control surface.
I ran the power line down the same tube right next to the audio snakes, but I did so down "3-wire-plus-shield" power cable, which also had a 'slow twist' to the three conductors inside the shield.
From that one installlation I can say that my fears about noise hopping from power to audio turned out to be unfounded. -I really did expect some sort of probelm to solve, but even with the UPS running, we never had any buzz or nastiness, over something like a 45-50 foot adjacent span.
-Of course in addition to the power source being 'balanced', the audio lines were the original Neve design inputs & outputs, and they were not too shabby at rejecting stuff, but I do have to confess, I was mightily relieved that there were no problems whatsoever... -If the truth be told, I don't think I had a fallback plan! :shock: :wink:
Keith
[quote author="mediatechnology"]Bob, the topic reply thing quit working so I had no idea you had posted, Sorry for the delay.
I think you'll only get significant noise cancellation in a 240V CT situation is when you connect your loads 240V leg-leg. Like Equitech only at 240V.
Will re-read your cable question and get back with you soon.[/quote]
OK, so it's single phase then... you just saved me over $1000! I'm getting email notices, by the way, Wayne...
BK
I think you'll only get significant noise cancellation in a 240V CT situation is when you connect your loads 240V leg-leg. Like Equitech only at 240V.
Will re-read your cable question and get back with you soon.[/quote]
OK, so it's single phase then... you just saved me over $1000! I'm getting email notices, by the way, Wayne...
BK
[quote author="mediatechnology"]Bob;
Going back to the cable RF iso-trans question I think that tieing the RF-iso primary back to studio U-ground would defeat both the RF iso and the power iso. That primary is going to be tied to utility ground at the cable company's grounding block (we hope). It sure couldn't hurt to tie the secondary down to studio ground though.
For your ethernet lines take a look at these DIN-rail surge protectors for industrial ethernet.
http://www.bb-elec.com/bb-elec/literature/IASP1P-0403.pdf
Also check Black Box http://www.blackbox.com/Catalog/Detail.aspx?cid=45,75,1426&mid=2003
These are industrial-strength (literally) protectors.[/quote]
I have been using Furse
http://www.furse.com/esp/products.asp
I had to order direct from England. The model ESP LN is the lower cost "less strong" model that I use for the shorter runs and I use the ESP Net 100 that you see here for the long runs and especially where the Cable modem plugs into my router.
We don't have any din rails here... I made a grounding bus bar at my punch block and grounded a bunch of ethernet protectors via their included 3" strap to the bar and then grounded the bar to the chassis of my UPS. It seems to work
Going back to the cable RF iso-trans question I think that tieing the RF-iso primary back to studio U-ground would defeat both the RF iso and the power iso. That primary is going to be tied to utility ground at the cable company's grounding block (we hope). It sure couldn't hurt to tie the secondary down to studio ground though.
For your ethernet lines take a look at these DIN-rail surge protectors for industrial ethernet.
http://www.bb-elec.com/bb-elec/literature/IASP1P-0403.pdf
Also check Black Box http://www.blackbox.com/Catalog/Detail.aspx?cid=45,75,1426&mid=2003
These are industrial-strength (literally) protectors.[/quote]
I have been using Furse
http://www.furse.com/esp/products.asp
I had to order direct from England. The model ESP LN is the lower cost "less strong" model that I use for the shorter runs and I use the ESP Net 100 that you see here for the long runs and especially where the Cable modem plugs into my router.
We don't have any din rails here... I made a grounding bus bar at my punch block and grounded a bunch of ethernet protectors via their included 3" strap to the bar and then grounded the bar to the chassis of my UPS. It seems to work
I just finished up the Topaz transformer (in my copious free time), hooked it up to the 2 phase incoming line and it puts out 127 to perhaps 130 volts AC on its output, unloaded. Ouch!
Remember, I'm paralleling two secondaries, that lowers the output impedance and maybe raises the capability, but this is UNLOADED>
Is this a problem? Maybe this transformer's ratios were designed for the days when it was 220 volts in and not 240....
Can I use this, almost 130 volts on its secondary. OUCH!
Remember, I'm paralleling two secondaries, that lowers the output impedance and maybe raises the capability, but this is UNLOADED>
Is this a problem? Maybe this transformer's ratios were designed for the days when it was 220 volts in and not 240....
Can I use this, almost 130 volts on its secondary. OUCH!
> Can I use this, almost 130 volts on its secondary. OUCH!
Plug in a 100 watt lamp and see if it sags. But I doubt it.
There are no primary or secondary taps?
What voltage is going into it?
Are you sure the winding is 230V input, not 208V (hot-legs of 3-phase power)? We get that problem a lot here at work. People think they can get 230V power, but they can't, we have to use autotransformers. Conversely, if you have only split-phase 230-240V, Murphy's Law says you will bring home a 208 winding.
This is what, 2KVA? Get a 250VA 240V:24V transformer, wire it as an auto-transformer. If you get 250V, swap the leads on the 24V winding so you get like 220V. This is how we jack 208V to 230V; you can do the same in reverse. Test with a 100W 120V lamp in series with the whole contraption so it you wire it shorted, you get a flashbulb instead of a fire.
Plug in a 100 watt lamp and see if it sags. But I doubt it.
There are no primary or secondary taps?
What voltage is going into it?
Are you sure the winding is 230V input, not 208V (hot-legs of 3-phase power)? We get that problem a lot here at work. People think they can get 230V power, but they can't, we have to use autotransformers. Conversely, if you have only split-phase 230-240V, Murphy's Law says you will bring home a 208 winding.
This is what, 2KVA? Get a 250VA 240V:24V transformer, wire it as an auto-transformer. If you get 250V, swap the leads on the 24V winding so you get like 220V. This is how we jack 208V to 230V; you can do the same in reverse. Test with a 100W 120V lamp in series with the whole contraption so it you wire it shorted, you get a flashbulb instead of a fire.
[quote author="PRR"]> Can I use this, almost 130 volts on its secondary. OUCH!
Plug in a 100 watt lamp and see if it sags. But I doubt it.
There are no primary or secondary taps?
What voltage is going into it?
[/quote]
Thanks for writing, PRR! This is a "2.5 kva" transformer with identical primary and secondary windings in the classic "dual winding" that can either be series or parallel or dual 120-0-120 on either the primary or secondary. So, it should be producing EXACTLY half of its input on its output, but it's not.
I've got 242 volts going into the primary which is set up as both windings in series and I have the secondary as a single parallel secondary, and it's putting out 127 volts.
There was no official documentation with the transformer, it lost its Topaz plate and Skycraft says it's a Topaz. I know it's a Topaz, no one's ever done a clone that looks this close.
I bought it at Skycraft in what looks like totally new, unused condition, not a scratch on it anywhere. The management at Skycraft had labelled it as a 2.5 kva 220/110 input/output transformer, or maybe they labelled it as 240/120, I can't remember.
It also has TWO electrostatic shields.
It was definitely not a 208, I would have shyed away from that.
Well, first thing, do I have to worry with 127 volts feeding the audio studio? It does sound very high, but that's less than 10%.
How did you calculate 250 va for the autoformer? I forgot about that autoformer trick! You're saying take the secondary and wire it in series with the primary, put the full voltage across the total, and then tap the lower voltage out of the primary?
Thanks,
Bob (grumble, grumble)
Plug in a 100 watt lamp and see if it sags. But I doubt it.
There are no primary or secondary taps?
What voltage is going into it?
[/quote]
Thanks for writing, PRR! This is a "2.5 kva" transformer with identical primary and secondary windings in the classic "dual winding" that can either be series or parallel or dual 120-0-120 on either the primary or secondary. So, it should be producing EXACTLY half of its input on its output, but it's not.
I've got 242 volts going into the primary which is set up as both windings in series and I have the secondary as a single parallel secondary, and it's putting out 127 volts.
There was no official documentation with the transformer, it lost its Topaz plate and Skycraft says it's a Topaz. I know it's a Topaz, no one's ever done a clone that looks this close.
I bought it at Skycraft in what looks like totally new, unused condition, not a scratch on it anywhere. The management at Skycraft had labelled it as a 2.5 kva 220/110 input/output transformer, or maybe they labelled it as 240/120, I can't remember.
It also has TWO electrostatic shields.
It was definitely not a 208, I would have shyed away from that.
Well, first thing, do I have to worry with 127 volts feeding the audio studio? It does sound very high, but that's less than 10%.
How did you calculate 250 va for the autoformer? I forgot about that autoformer trick! You're saying take the secondary and wire it in series with the primary, put the full voltage across the total, and then tap the lower voltage out of the primary?
Thanks,
Bob (grumble, grumble)
[quote author="mediatechnology"]Bob;
If you're getting 127 volts unloaded at the output you have the right transformer and tap settings. We typically have 125 v lines here in Texas. If it were 208 primary the output would be in the 138-140V range.
SNIP
[/quote]
Thanks, Wayne! Anything to avoid building that autoformer that PRR recommended. This Topaz is going into an APC UPS, we'll see if it coughs at the source voltage. I'll watch source and load with my Fluke for the next few days. I'll bet that 127 unloaded will drift closer to your 124 after I start hooking up loads.
As for light bulbs, well most everything on audio gear these days are LEDs and they are being powered from the regulated power supply. It's good to hear you don't think most audio gear would cough at up to 130 volts. Of course I'd like to hear other opinions!
If you're getting 127 volts unloaded at the output you have the right transformer and tap settings. We typically have 125 v lines here in Texas. If it were 208 primary the output would be in the 138-140V range.
SNIP
[/quote]
Thanks, Wayne! Anything to avoid building that autoformer that PRR recommended. This Topaz is going into an APC UPS, we'll see if it coughs at the source voltage. I'll watch source and load with my Fluke for the next few days. I'll bet that 127 unloaded will drift closer to your 124 after I start hooking up loads.
As for light bulbs, well most everything on audio gear these days are LEDs and they are being powered from the regulated power supply. It's good to hear you don't think most audio gear would cough at up to 130 volts. Of course I'd like to hear other opinions!
This morning I put a 4.5 AMP heat gun on it and the 125.9 volt (Fluke RMS) source dropped to 125.0, so I'm feeling a bit more comfortable. Running all night with NO LOAD, the laminations on this power transformer get VERY hot. I have asbestos fingers and I can't keep my hand on it for more than about 30 seconds before I say, "damn, that's hot". The main gunmetal-grey chassis is just a little warm, though. I'm talking about the black laminations in the middle between primary and secondary side. Is this normal?
BK
BK
[quote author="mediatechnology"]Yes Bob the laminations do run hot so I wouldn't worry about that.
I do think that once loaded it will drop down below 125V. The APC probably won't care too much either.
Wayne[/quote]
Thank you very much, Wayne.
Bob
I do think that once loaded it will drop down below 125V. The APC probably won't care too much either.
Wayne[/quote]
Thank you very much, Wayne.
Bob
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