Three phase sockets

[milkloss]

Afternoon All, miserable weather here so planning indoor stuff!

Am looking to put three 3ph 5pin sockets in the old parlour which is now a workshop and hoping for some advice/experiences as regards installation. I would be looking to put them in myself and get them tested by a qualified man later.

32amp sockets would be used for a mig welder, air compressor and pressure washer and not all at the same time. I am assuming the welder would be best without an rcd and just a standard C breaker should do this to prevent tripping as this is how it used to be wired. What about the compressor (not mobile and indoors)? The pressure washer I am sure will be needing an rcd as it may be used outside but not much, the pipe and lance obviously will be used outside all of the time.

What’s the ideal way of switching and fusing these sockets? I know there are sockets that come with a small din rail enclosure and isolator but I suspect they are pricey. One option is to run some 5wire (not a fan of terminating swa sheath in plastic boxes) to an extra distribution box and fuse/protect there then run off to the sockets and isolator I suppose.

Ideas appreciated.

 

[Cjm]

I’d discuss it with the sparky who has to sign it off first, as I’m pretty sure all socket outlets should be rcd protected. For your compressor for instance, why use a socket and plug when you could wire it straight to an isolator?

 

[Bob c]

fused at the board then

https://www.superlecdirect.com/site...3p-n-and-e-32amp-switched-interlocked-socket/

 

[Barleycorn]

Surprising how cheap Toolstation are on electrical stuff (and everything else).

 

[milkloss]

I’d discuss it with the sparky who has to sign it off first, as I’m pretty sure all socket outlets should be rcd protected. For your compressor for instance, why use a socket and plug when you could wire it straight to an isolator?

I agree the spark will have to be happy but might also want the Rolls Royce of efforts which isn’t going to happen. Safe but not ott is what we’re after

As regards the welder socket, it’s my understanding that very often rcd’s And welders don’t make good bed fellows hence the Mcb only. Not averse to giving it a try though. Is it standard practice to use one rcd for three sockets or rcds individually to save tripping all three?

Compressor needs a socket because it saves a load of hassle when at some point it’s going to need working on and there’s not much safer than pulling a plug! Oh and it will be in a position where something else might need power every now and again: saw bench, lead for auger etc etc. No point limiting your options for a few quids worth of plug and socket is there?

This brings me on to the final point before the clip boards get here: yes, I should leave an open cheque book for a qualified man to draw up schematics, install it, take his cut, test it and take the blame when someone feels the need to blame everyone else! But I don’t have a slush fund and it is not in my character to blindly fund someone else’s aspirations for the perfect install. I am aiming for a safe installation and will consult at a cost if necessary but am hoping for practical and real life experiences from the good folk on TFF

 

[milkloss]

fused at the board then
View attachment 633766

https://www.superlecdirect.com/site...3p-n-and-e-32amp-switched-interlocked-socket/

Thanks Bob, looks just the ticket. I forgot about superlec

 

[REStracTORATION]

fused at the board then
View attachment 633766

https://www.superlecdirect.com/site...3p-n-and-e-32amp-switched-interlocked-socket/

We have them for welder plug and then a 32 supply to the compressor via the main RCD boards to a hard wired plug which then feeds the compressor switch board/panel

What we are having trouble with is the cutout switch's on the pump motors we have been adviced to up them from 15a to 20a
Mainly due to when spraying the compressor can run for an hour or 3.

 

[roscoe erf]

32amp for a welder what the f**k are you welding the titanic

 

[milkloss]

32amp for a welder what the fudge are you welding the titanic

If it can draw it, it’ll need a plug and cable to match!

 

[Tarw Coch]

32amp for a welder what the fudge are you welding the titanic

My shed builder and electrician are big buddies, when we were putting in a new dairy set up shed builder got electrician to put a 32 amp socket in for welder here. I don't do a lot of welding but bought myself some new cable and 32 amp connectors andnow hook into this Sockett. All I can say is the welder seems to run a lot nicer on it

 

[spanners and hammers]

We have them for welder plug and then a 32 supply to the compressor via the main RCD boards to a hard wired plug which then feeds the compressor switch board/panel

What we are having trouble with is the cutout switch's on the pump motors we have been adviced to up them from 15a to 20a
Mainly due to when spraying the compressor can run for an hour or 3.

have you got motor rated trips ? as we had similar trouble and changed trip cured it something to do with the extra start up load

 

[spanners and hammers]

I’d discuss it with the sparky who has to sign it off first, as I’m pretty sure all socket outlets should be rcd protected. For your compressor for instance, why use a socket and plug when you could wire it straight to an isolator?

think you can have a main rcd switch on incoming then trips in board

 

[roscoe erf]

If it can draw it, it’ll need a plug and cable to match!

View attachment 633862

over 3 phases that is not going to draw any where near that look at the plate and look at 415v at the max draw what does it say

 

[milkloss]

over 3 phases that is not going to draw any where near that

No, it probably won’t. In fact it has been used on a three phase extension cord in the past but didn’t run very nice at all, never really used over 200 Amps but you can guarantee some idiot will try! It’ll get its own 32amp socket and I’ll run a couple of 16amps for the other gear with rcd, debating at the moment if the 32amp socket should have one or not.

Label says 29amp draw, 415v at 60% duty cycle. I’ll have to have the cover off because it is most likely a two phase weld unit and the third used for the wire feed.

 

[roscoe erf]

No, it probably won’t. In fact it has been used on a three phase extension cord in the past but didn’t run very nice at all, never really used over 200 Amps but you can guarantee some idiot will try! It’ll get its own 32amp socket and I’ll run a couple of 16amps for the other gear with rcd, debating at the moment if the 32amp socket should have one or not.

Label says 29amp draw, 415v at 60% duty cycle. I’ll have to have the cover off because it is most likely a two phase weld unit and the third used for the wire feed.

they usually are mine are on rcd you just need a c or d rated one

 

[milkloss]

they usually are mine are on rcd you just need a c or d rated one

It doesn’t trip a C rated one how we use it at the minute but we do have a big oil coil single phase stick welder that gets the odd use. They’ll trip an rcd until they get warm and cook the condensation out.

I thinks it’s going to be trial and error a little bit

 

[TheTallGuy]

See https://electrical.theiet.org/wiring-matters/54/rcd-protection-of-sockets/index.cfm, which suggests it may be acceptable to omit the RCD, but without site specific information it's impossible to say for certain if it would be acceptable as it's sometimes required to comply disconnection times for phase-earth faults.

There's no problem terminating SWA into appropriate plastic boxes - most 32A socket boxes are fine & designed for it, otherwise you would be looking at doing it with conduit and singles. Always try to ensure that you buy interlocked sockets to prevent live disconnection as that soon knackers the connections.

 

[rob h]

We put a new socket in for a welder last year. With rcd and told them what we were powering when we bought the gear.they had different trips for such applications.

 

[Pheasant Surprise]

None of our 3-phase sockets in the workshop were wired with an RCD, this about 2014 ish. Just C-rated 3-pole breakers. Welder, compressor and washer all run off them either 16A or 32A sockets.

Go interlocked as advised, think ours are Gewiss. So not ABB quality but totally fine.

There is a main 100mA RCD on the incomer from the main board but this is for fire/wiring rather than human protection.