Three phase extension lead with single phase socket outlets

tex431 · Sep 21, 2016

I was flicking through the Scame catologue at the wholesalers today and noticed a picture in the catologue of a three phase extension lead, and on the reel it had single phase socket outlets on. It got me thinking, What would be stopping you wiring a three phase plug on to a single phase appliance and just coming coming off a phase ?
http://www.electrex.co.nz/uploads/86313/images/418797/CABLE-ROLLER-WITH-2-OUTLETS.png

westward10 · Sep 21, 2016

Nothing it would function assuming a neutral is present. Bit like connecting a single phase circuit from a triple pole board. Why you think these things.

tex431 · Sep 22, 2016

Y

westward10 said:
Nothing it would function assuming a neutral is present. Bit like connecting a single phase circuit from a triple pole board. Why you think these things.

Yes, I know it would work, thanks.

Darkwood · Sep 22, 2016

The problem is you have the obvious issue of been able to partly energise 3ph equipment by plugging in a 3ph item to a socket with only 1ph present which should not be the case, with respect to the 1ph outlet from a 3ph/N supply then you can only plug in the correct item that requires 1ph. Also unless you single phase all the 3ph pins, you would need to ensure any plug is matched to the live pin but from my first point, you shouldn't be rigging this setup up anyway but having said that, it does go on in the land of the cowboy sparks.

spary · Sep 22, 2016

happens all the time using 2ph welders on 3ph sockets

Darkwood · Sep 22, 2016

True @spary but 2ph welders don't require correct the phone rotation so you cannot really get it wrong picking any 2 phase pins on the welder plug.

spary · Sep 22, 2016

I can't see the problem, if the 3 ph socket is wired correctly using all 3 supply phases + N?
your appliance might only need 240v but uses a 5 pin plug ???
you can plug any appliance in that fits, whether it needs 1,2 or 3 phases

Darkwood · Sep 22, 2016

The OP was talking about a 3ph plug onto a single phase supply and that is what I was relating to, of course if you have a plug with 3ph and N then no issue if using only a few phases.

westward10 · Sep 22, 2016

The most important thing here is that the socket is wired correcty. I see absolutely no problem connecting a single phase appliance through a triple pole plug.

Mark42 · Sep 29, 2016

I agree, no problem in supplying a single phase 230V appliance from a (five pin) red TPN plug/socket, using any one phase and the neutral.
Unwieldy and potentially confusing perhaps, but electrically OK.
But remember it will be protected somewhere by a three-pole breaker (which may not be RCD-protected), so a fault on the single-phase appliance will trip all the phases.
I say 'So what?', but when I suggested an equivalent install on one circuit in my new workshop (to get around a cable limitation), I got a load of nay-saying and abuse. But, perhaps significantly, I'm still waiting to hear why this is not acceptable.
One three-phase breaker, supplying multiple single-phase loads. OK or not? - http://www.electriciansforums.co.uk/threads/one-three-phase-breaker-supplying-multiple-single-phase-loads-ok-or-not.111198/