Direction of connection of RCD

kildarejohn · 09-12-2022 1:57pm #1

I had a new RCD installed on my home distribution board a couple of months ago. This was an exact replacement for the original which dated from around 1990, and was wired the same way. Last week an electrician was doing a job connecting a new circuit, and he said RCD was wrongly installed because L/N wires from main fuse/meter were fed into top 2 terminals on RCD and feed out to sockets etc were from bottom of RCD. He said connections were the wrong way around.

While not up to date with current regs, I know the basics. AC current is two way, so the direction of connection should make no difference at all to the safe operation of the RCD. Any one have views?

kirk. · 09-12-2022 4:04pm

Don't think it affects operation of rcd

Press test button and do a trip test anyway to be sure

iwillhtfu · 09-12-2022 4:07pm

It'll make little to no difference but typically supply is through the bottom. He may well have found out by turning it off and pulling out live cables assuming previous.

kirk. · 09-12-2022 4:13pm

https://www.boards.ie/discussion/comment/119975604#Comment_119975604

He would have found out just by looking at the wiring, it's obvious

If I remember correctly there was some boards came wired that way , can't remember now

They're best wired with supply in the bottom because that's the convention and what u expect

kirk. · 09-12-2022 4:17pm

https://www.boards.ie/discussion/comment/119975604#Comment_119975604

No electrician will be pulling out live cables unless he's an idiot

iwillhtfu · 09-12-2022 4:26pm

https://www.boards.ie/discussion/comment/119975650#Comment_119975650

Unknowingly so I could see how it would happen. Anyone that would think it couldn't would be a fool 🤷‍♂️

iwillhtfu · 09-12-2022 4:29pm

https://www.boards.ie/discussion/comment/119975628#Comment_119975628

You know what they say about assuming. As I said and you repeated for some reason 🤷‍♂️ typical wiring is through the bottom.

kirk. · 09-12-2022 4:38pm

https://www.boards.ie/discussion/comment/119975689#Comment_119975689

And why exactly would an electrician be pulling out wires out of an rcd without switching off supply ?

If he was changing the rcd he would have switched off beforehand

iwillhtfu · 09-12-2022 5:00pm

https://www.boards.ie/discussion/comment/119975743#Comment_119975743

I have no idea why they would or if they did but also not naïve enough to believe accidents don't happen. I'm not entirely sure what your issue is but perhaps sit down and talk it though with someone as that chip must get tiresome.

I think you've dragged the thread off topic enough now. OP I'm sure you have your answer 👍

kirk. · 09-12-2022 5:04pm

https://www.boards.ie/discussion/comment/119975847#Comment_119975847

There is no reason to pull out live cables

That's my point it didn't happen

12-12-2022 7:30pm

It wouldn't make any difference to the operation of an RCD, but in Irish wiring regulations the polarity of circuits is very strictly maintained throughout the whole installation. There's no ambiguity about that around what kind of devices are connected.

Antenna · 16-12-2022 5:32pm

Possibly the convention (supply in at the bottom) is considering that loose wires or other conductive debris is more likely to come in contact from above rather than below.

On an RCD which disconnects both L and N, electrically it will not matter which side is supply or load.

However if it is a single pole RCBO (which does not switch the neutral) it seems the test button's resistor can burn out, if connected the other way, as it ends up across the (unswitched) neutral and the incoming live (rather than outgoing live, which should immediately disconnect when its pressed)) and if someone keeps the button pressed for long enough it rapidly heats up and burns out.

Direction of connection of RCD

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