IEC socket with two fuses.. hmm..

[monobass]

So I bought a fused IEC socket which requires two fuses to operate, one on live, one on neutral.
I thought I was buying a socket with only one fuse.

Now i'm in the UK so the actual wall plug will be fused also. I now seem to be in fuse overkill

So how do I rate the two fuses to go into the IEC socket?

I'm using a 2x15v 30VA (1.0A) toroid in this build.

 

[radiance]

Put in one hefty one that acts as straight wire.

For the other one, which acts as the actual fuse, measure current draw for whatever it is your building. Use a slow blow fuse rated just above the current draw.

 

[monobass]

makes total sense cheers, I'll just stick a 15A fuse in the neutral one.

 

[Andy Peters]

So I bought a fused IEC socket which requires two fuses to operate, one on live, one on neutral.
I thought I was buying a socket with only one fuse.

Now i'm in the UK so the actual wall plug will be fused also. I now seem to be in fuse overkill

So how do I rate the two fuses to go into the IEC socket?

I'm using a 2x15v 30VA (1.0A) toroid in this build.

The tech here who is the one responsible for pushing stuff through TUV testing, tells me that they require fusing on both the hot and neutral.

Determine the current draw. Choose a fuse rating somewhat above that draw, and use that value for both legs.

-a

 

[monobass]

Thanks - I guess I'll experiment, as long as I start low all I can lose is time and money

 

[PRR]

The plug-fuse protects the cord. Using common IEC cable, these may be 5 Amp or more, whatever is common for computer cords there. These would never blow unless the cable were damaged. (I have seen VERY thin wire on UK gear; one seemed to lack fuse-plug and was probably expected to burn-up without drama; but if you have fuses on thin wire then look around for similar fitting on commercial gear and copy the fuse rating.)

The at-entrance fuses protect against dead-shorts burning-up the transformer. If you plan to use most of the rated 30VA, on 230V wall, these would be at-least 30VA/230V= 0.13A. In fact the start-up surge is often more than the running current and won't hurt the transformer. On US 120V power I would use at least 0.5A; on your 230V juice this may be 0.25A or whatever is the next common size (0.312A?).

 

[mikeyB]

So I bought a fused IEC socket which requires two fuses to operate, one on live, one on neutral.
I thought I was buying a socket with only one fuse.

Now i'm in the UK so the actual wall plug will be fused also. I now seem to be in fuse overkill

So how do I rate the two fuses to go into the IEC socket?

I'm using a 2x15v 30VA (1.0A) toroid in this build.

The tech here who is the one responsible for pushing stuff through TUV testing, tells me that they require fusing on both the hot and neutral.

Determine the current draw. Choose a fuse rating somewhat above that draw, and use that value for both legs.

-a

Is this sound advise? I,d be worried about someone not familiar opening the unit to poke about with the potential (pun intended) to touch mains voltage because only the neutral fuse has blown!
I,d feel happier with neutral strapped (or big fuse) and calculate the other - 30VA at 230V implies 130mA current - Not sure of the next higher rating but 250mA exist - using a toroid so make sure it`s a timed or antisurge fuse.

 

[PRR]

> I,d be worried about someone not familiar opening the unit to poke about with the potential (pun intended) to touch mains voltage because only the neutral fuse has blown!

I'd be worried about anybody who pokes inside, recklessly, without pulling the plug from the wall.

In building-wiring, fused-Neutral is generally banned because there is no easy way to *totally* disconnect both sides of the circuit.

But appliances have wall-plugs *so-that* they may be completely disconnected from power for service.

Among other reasons: with many wall-plugs and wall-outlets, there is no way to know which is "line" or "neutral". The German plug is undefined. Post-1970 US outlets have a wide pin, but in one study (my old kitchen) 60% were wired wrong.

Maybe it's different in the UK. In the US, I must always assume I do NOT know which un-green wire is which (and I'm never totally sure about that green wire either).

 

[monobass]

how can you distinguish neutral from ground if you don't know how a socket is wired?

 

[leadbreath]

i think in British standard the neutral must always be unfused (solid link), the fused neutral is used on continental europe.
as for the wiring colours, old standard black was always neutral, new standard blue is neutral.

 

[Brian Roth]

USA electrical code for typical 120 VAC "branch" circuits from the breaker/fuse panel to wall outlets specifies the (groundED) neutral wire must not be fused, and also have insulation that is white in color.  The "safety" groundING wire is either insulated with green, or is bare (in the case of type NM cable...aka "Romex").  The "hot" current carrying wires can be insulated with any color EXCEPT white or green.

The white insulated neutral wire should attach to the screw on the outlet which is on the side with the wider slots, and that screw will be "silver' in color.  The black/red/whatever "hot" wire attaches to the side of the outlet with the shorter slots, and the screw will be brass in color.  The green/bare groundING wire attaches to the screw at the top or bottom edge of the outlet, and that screw will be colored green.

That's how it's supposed to be, anyway.  As PRR noted, some brain dead electrician may have swapped the hot and neutrals on any given outlet, such as I also discovered in my own house.

Best,

Bri