RCD requirements for outside socket

[bsr]

Hi, what is the current requirement for RCD additional protection on a socket circuit? Is it for just the socket outlets or for the whole circuit?

I have builders in, who keep tripping the RCD with their mixer, pump, breaker etc. I have given them a dedicated circuit on it's own RCBO which at least means they are not taking out other parts of the house. However the RCBO keeps tripping - I've ramp tested it to 22mA and there's <2mA of natural leakage. I'm on TN-S with Zs 1.6.

Would it be acceptable to move the circuit back to a non-RCD protected MCB and change the socket to an RCD socket? At least that way they could re-set it themselves without having to come into the house. That would protect the equipment but not the circuit.

Or would it be OK to log a deviation to temporarily (months) provide a non-RCD protected circuit only for construction use? Do construction temp supplies use RCDs?

Cheers

 

[blup]

Ask the builders to use a generator, shouldn't they use 110 volt in any event?

 

[ebee]

No.
Builders are notorious for having equipment that is damaged/faulty and liable to trip an RCD.
They also are likewise for overloading circuits (extension leads) by trying to run about 17 items of equipment on one fuse or breaker.
So they might be tripping either tge RCD element or the MCB element or both.
So, you supply a safe socket that is RCD protected and let them use correct safe equipment otherwise you could be in breach of health and safety

 

[Murdochcat]

Start up current of their tools is probably tripping the RCBO

I wouldn’t be removing RCD protection from the sockets to

How have you “given” them a dedicated circuit?

 

[ebee]

Correct. The start up current could be excessive

 

[bsr]

How have you “given” them a dedicated circuit?

It's an old cooker circuit on a B32. No longer used for cooker so I relocated the T&E outside in conduit and put an IP68 socket on the end.

Correct. The start up current could be excessive

I'm pretty sure it's not inrush current. I moved them onto an RCBO because previously it was a twin RCD board and they were tripping the RCD and taking out half the house. The MCB was fine.

 

[bsr]

Supply a safe socket that is RCD protected and let them use correct safe equipment otherwise you could be in breach of health and safety

So is an RCD socket acceptable, supplied from a non RCD protected circuit? The circuit is concealed not surface run.

 

[ericmark]

With a 110 transformer any equipment is not going trip RCD so the transformer must be faulty. It is not an option to use 230 volt tools on a building site, I don't agree with the rule, I think yellow bricks are a fire hazard, but there is no option, all construction site equipment has to be 110 volt. (55-0-55 or 64-0-64 if three phase)

In-rush with a RCD is strange, theroy it should not trip a RCD, however I know from experience turning a whole fuse box on would trip the RCD but turning on one MCB at a time would not trip it. I would say more likely tripped by a spike, but still it does seem as if tripped by in-rush.

I would think most likely problem is turning the transformer on/off at end of each use, if left plugged in you should not get a problem once first energised.

 

[bsr]

No transformer, they are 230v tools. They only do domestic.

 

[blup]

They're builders so they can call on a/their regular sparky to check out the problem which has started when their tools were used.

 

[bsr]

Can anyone either answer the question please or suggest a forum where I can get a straight answer?

 

[jurassic sparkk]

Bear with it.

 

[Murdochcat]

Can anyone either answer the question please or suggest a forum where I can get a straight answer?

This is a diy forum - up with some pros and quite a few DIYers

Maybe try a sparky forum?

 

[Murdochcat]

Why isn’t the builders spark sorting this out ?

 

[plugwash]

So is an RCD socket acceptable, supplied from a non RCD protected circuit? The circuit is concealed not surface run.

AIUI from the perspective of complying with current BS7671 there are two issues with using RCD sockets.

1. The standard for RCD sockets was not included in the list of acceptable standards for RCDs in BS7671. There have been claims that this was a mistake, but there has been a big f*ckup in the way standards are written and to the best of my knowlege this has not yet been fixed.
2. Concealed cabling has to be either RCD protected, or installed in specific ways (SWA, MICC, Steel conduit etc) that avoid the need for RCD protection. From what you have said earlier it doesn't sound like your cabling is installed in such a manner.