[sdiy] OT: Mains Safety PSA

Mike Bryant mbryant at futurehorizons.com
Fri Jan 14 17:23:33 CET 2022


In the UK each non-lighting breaker (usually rated at 30 amps), feeds two 2.5mm twin and earth cables, each rated at 23Amps which form a loop around all the sockets with the zone of that breaker.  So each socket has 46 Amps of cable capacity backing it up.

Whereas in the point to point wiring favoured on the continent there is only 23 Amps capacity in the single cable feed, which is why I said 26 Amps is to say the least marginal.


From: Chromatest J. Pantsmaker [mailto:chromatest at azburners.org]
Sent: 14 January 2022 16:13
To: Mike Bryant
Cc: Gordonjcp; synth-diy at synth-diy.org
Subject: Re: [sdiy] OT: Mains Safety PSA

I'm in the US, and I've done extensive house wiring here, but I know nothing about what is acceptable or even legal in other countries.

In the US, we run 120V for regular wall outlets.  The regular receptacles are rated at 15A.  The wiring needs to be rated for at least 15A, and the fuse/breaker can be rated no higher than the rating of the smallest wiring conductor between the breaker and outlets.  This is typically 14 gauge (with a 15A breaker) or 12 Gauge (with a 20A) breaker.  That breaker typically supplies *multiple* 15A receptacles, with the idea that they aren't going to all draw their rated maximum at the same time (if ever).  And if they do, the breaker trips or the fuse blows to protect the wiring.

So my question is, do other countries allow wiring with oversized breakers?  Why didn't Cheater's fuse/breaker save the day?  I would expect breakers in 240V countries to be even smaller thanks to Mr. Ohm.

On Fri, Jan 14, 2022 at 8:13 AM Mike Bryant <mbryant at futurehorizons.com<mailto:mbryant at futurehorizons.com>> wrote:
26 Amps is also marginal for the house wiring in many European countries.    Europeans never did understand the advantages of UK ring mains which are of course compulsory here in most situations :-)

-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org<mailto:synth-diy-bounces at synth-diy.org>] On Behalf Of Gordonjcp
Sent: 14 January 2022 13:55
To: synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>
Subject: Re: [sdiy] OT: Mains Safety PSA

On Fri, Jan 14, 2022 at 12:33:06PM +0100, cheater cheater via Synth-diy wrote:
> So as recent experience shows, 18 - 26 amps max continuous load for
> months was a tad optimistic for this unknown brand Schuko wall socket,

18A is somewhat and 26A is grossly out of spec for Schuko.

If you're going to pull that kind of power you need to look into getting a dedicated circuit and IEC60309 sockets fitted.  We use the 16A version for our "small" cabinets (where they mostly just power a single 24V rackmount PSU, with extra "UK plug" BS1363 sockets for plugging in test equipment.  For our server cabs we use the 32A version.

You might want to use the 32A version, too.

--
Gordonjcp

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