Driving a new ground spike

[leadbreath]

https://www.fluidaudiodesigns.co.uk/technical_earth/

 

[Matt Syson]

In the realms of recording studios, having the desk taken to a 'clean earth (dedicated thick cable and spike) while the multitrack uses mains earth is not 'optimal' when you have a thunderstorm. I had a trip to Malaysia to sort out the 24 'vapourised' tape return inputs, fortunately all the input op amps were socketed. I am presuming that the voltage 'pulse' that existed between the correctly wired mains system and the 'tech earth' spike was actually only in the region of 30 Volts as only the input unbalancing buffer amps suffered. Even the desk computer automation survived intact.
Matt S

 

[Newmarket]

To be realistic - very few (by which I really mean none) protection schemes are going to be full proof against 'worst case' lightning strikes.
Outside of audio applications - I've had kit from Geotechnical Instrumentation fed back to me and I can see the scorch marks from a HV hit. This stuff had much protection in terms of transients and Earth conductors but sometimes it's just not enough !

 

[Bo Deadly]

It sounds like there is a misconception about having a separate spike for studio gear. As stated previously, I think there should be only one in the building. And if there is more than one, they better be completely separate circuits. The panel could have two circuits. That should provide good separation between the studio and all of the other stuff like sump pump, HVAC, microwave, fridge, etc. Specifically, the panel is at the service entrance with a short thick connection to a good quality ground spike. The panel has two circuits that share earth ground to said spike. When lightning strikes, everything is still relative to the one ground spike and so there shouldn't be differences in ground potentials to fry stuff.

 

[Brian Roth]

I might be mistaken, but I recall reading that the NEC (here in the USA) requires that all grounding rods in a building's system MUST be all bonded together along with the water plumbing.

Bri

 

[shabtek]

even between sub-panels?

 

[Speedskater]

some serious grounding systems:

Grounding Systems

SRPP :: System Reference Potential Plane
STGP :: Signal Transport Ground Plane
ZSRG :: Zero Signal Reference Grid
ZSRG :: Zero Signal Reference Conductors
ZSRP :: Zero Signal Reference Potential
ZSRP :: Zero Signal Reference Plane
MESH-CBN :: Meshed Common Bonding Network
MESH-IBN :: Meshed Isolated Bonding Network
PEC :: Paralleled Earth Conductors
PBC :: Paralleled Bonding Conductors

although Keith Armstrong prefers to call them Conductive Structures

 

[JohnRoberts]

I like to say "ground is a concept", YMMV

JR

 

[abbey road d enfer]

Ok, so it seems there are two things going on here.

1) The video at 1:37 explains "Since the copper strips are all at the same potential, the net electric field inside the cylinder is always zero as we move the rod around". Meaning the even distribution of charge on the surface equates to a net field of zero within. If there was any kind of hole or slit or even a kink in the shield, it would not evenly distribute the charge and therefore changes in the external E field would be observable.

I believe we all agree that for 100% efficiency, a shield must be exempt of openings.

2) Even if the shield is NOT kept at a constant potential, the net distribution of charge around the shield is still zero but these changes are still visible to the inner conductor.

If is clear that the shield must be kept at a potential that is constant referenced to the audio circuit reference; in that case, there can't be variations of the electric field inside the shielded enclosure and wiring.

 

[abbey road d enfer]

In the realms of recording studios, having the desk taken to a 'clean earth (dedicated thick cable and spike) while the multitrack uses mains earth is not 'optimal' when you have a thunderstorm.

I would even say that it's not necessarily a good solution in terms of noise. Having the mains earth and the audio earth separated means there could be longitudinal voltages between them. Pro audio gear should be relatively immune to that, but in almost every studio in the world there is an electric guitar...

 

[abbey road d enfer]

https://www.fluidaudiodesigns.co.uk/technical_earth/

Don't take this too seriously. These are good recommandations, but very short on explanation and don't differentiate the various causes of noise, conducted emissions in Line and Neutral conductors do not produce the same effects than conducted emissions in earth conductors, electrostatic fields are not differentiated from magnetic fields...and so on.

 

[Speedskater]

OK, so in a US type NEC (120/240V) AC power system:

a] the Safety Grounds are connected to the power company Neutral at the main breaker box.
the metal parts are bonded (attached) to the Safety Ground
the Safety Ground wire follows the Hot & Neutral wires (in close proximity) back to the main breaker box.

b] the Grounding Electrodes (ground rods, water pipe,or Ufer) connect to the power company Neutral at the main breaker box.

So while there is continuity between the Safety Grounds and the Grounding Electrodes, their tasks or functions are different.

 

[abbey road d enfer]

OK, so in a US type NEC (120/240V) AC power system:

a] the Safety Grounds are connected to the power company Neutral at the main breaker box.
the metal parts are bonded (attached) to the Safety Ground
the Safety Ground wire follows the Hot & Neutral wires (in close proximity) back to the main breaker box.

b] the Grounding Electrodes (ground rods, water pipe,or Ufer) connect to the power company Neutral at the main breaker box.

Just to make sure I understand: Safety grounds are the green wires coming from appliances and outlets going to the breaker panel, good?
What are the "metal parts" you mention?

So while there is continuity between the Safety Grounds and the Grounding Electrodes, their tasks or functions are different.

Are they? I don't think the electric company cares about hum in recording studios...

 

[JohnRoberts]

Just to make sure I understand: Safety grounds are the green wires coming from appliances and outlets going to the breaker panel, good?
What are the "metal parts" you mention?

In some very old wiring the EGC (equipment grounding conductor) was bare wire, but yes green in typical modern 3-conductor insulated wiring. (Line or hot is typically black, and neutral return is white). But trust that color code at your own risk. My house is clearly not to modern code (2-conductor wiring).
Metal parts likely refers to plumbing (copper) in older homes.

I have subsequently cobbled in safety ground wires for the outlets in my kitchen and laundry room. I even bonded my copper pipes and water heater chassis to my electrical panel, it was all floating before. I also upgraded to GFCI outlets near water/shock hazards, which can protect meat puppets even without EGC path.

Are they? I don't think the electric company cares about hum in recording studios...

UL certainly doesn't, their primary focus is human safety.

JR

 

[ccaudle]

Metal parts likely refers to plumbing (copper) in older homes.

Also metal outlet boxes, metal conduit (in North America at least typically only found in commercial construction, not residential housing, although may be in apartment style housing), and any metal building framing.

 

[scott2000]

Also

Gas lines?

 

[FIX]

I remember doing a live recording gig in St Lucia, we had the wonderful combination if 230VAC 50Hz, mixed with 120VAC 60Hz. Tying them together was the equivalent of tying two grids together with the bass player.

 

[One F Sound]

Speaking of St. Lucia, I worked at a studio in the Caribbean and the guy that helped build the place told me to water the ground spike when the noise floor started to creep up. Sure enough, the noise would drop down a bit.

 

[ccaudle]

Gas lines?

Yes, gas and water lines must also be connected to building ground.

I have only worked on systems within a single building, but as Bill Whitlock (Mister CMRR) has pointed out to me in the past, because anything metal is connected to the building grounding conductor, if you have something like a patch bay in a commercial building, the exposed metal has to be connected to building ground. That is why the XLR cabling standard still has pin 1 for shield connection which is not connected to the connector shell in cables, so that when the cable shell is grounded by a patch panel connected to building metal, you do not get multiple connections of a cable shield to building ground on a long connection going between buildings, or between different electrical service entrances in a really large building.

 

[abbey road d enfer]

, because anything metal is connected to the building grounding conductor, if you have something like a patch bay in a commercial building, the exposed metal has to be connected to building ground.

I'd be curious to know the extent of that regulation. I know and understand that any mains-powered appliance or apparatus has to be earthed, but I fail to see the logic of earthing a patchbay for safety or regulatory reasons.