An enigma for Adam

Dec 10, 2019 Last reply: 6 years ago 9 Replies
T

The builders on the neighbouring construction site demanded a single phase supply to power their portable tools. I suppose words beginning F and O are in order but, as I had a beneficial financial involvement in the development, chose to comply. The only convenient source is the socket outlets in what was our garage (now sold with incomers Friday). 20 year old install, Wylex 40 amp RCD.



On 3 occasions, something they do before leaving site, trips the breaker. Not in itself a problem but it also supplies power to the only entrance doors! I have taken to leaving a door open while the site is active as the alternative is winding the door up using a very tedious manual system. Not something I can expect the new owners to take on.



Communicating *get your tools PAT* checked is difficult as I don't speak any Romanian.



Last job of the day is plug in the chargers and batteries I guess although I have a 9" angle grinder which will occasionally trip a supply.



Any ideas?


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S

I suspect that RCD has a leakage current trip threshold of 30mA.

I would replace the RCD with a 2 pole isolator switch, and replace all the MCBs for RCBOs, use a separate RCBO for the doors, and split up your circuits and put an RCBO on each smaller circuit.

You will then find it easier finding out which power tools are tripping the RCBO.

S.

S.

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A

So RCD tripping but no MCB tripping?

But always at the end of the shift?

I wonder if they are switching stuff off and they are switching it off with a DP switch.

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Page 31. Caused by capacitors.

Well that's my best guess fella.

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T

Hmm.. It won't be my garage to do anything!

Might be easier to bring a second feed from the main isolator and have the socket protection outside the garage where they can reset it themselves.

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B

I take it you have heard the songs lyrics translated by google and sung on youtube? Get a very very long extension only for battery chargers and turn off the other supply before they go? Brian

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T

Page 31 seems relevant:-)

I think their last job would be plugging in the portable equipment battery chargers. I suppose they would be switching off any other stuff.

Screwfix do a BG. RCD protected weatherproof twin socket outlet. If I jump about, I can fit one of those on the outside wall and fed from the main isolator (32 amp HRC fusing I think).

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A

Sounds fine. They are better off with their own access to the RCD.

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T

Right. Job done. Pulling 4mm singles through 20mm conduit on your own is slow.

Changing a faulty twin socket on the original circuit I managed to demonstrate that a Neutral/Earth fault trips the RCD:-) (I needed the power on for the lead lamp so was relying on the MCB for isolation)

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