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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> RCD did not trip https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1441615246 Message started by TK80 on Sep 7^th, 2015, 9:40am

Title: RCD did not trip
Post by TK80 on Sep 7^th, 2015, 9:40am

I need some help from an expert as I have been researching and cant find the answers online.

Recently the switch pull cord snapped when trying to turn on my power shower. Its fairly old and the string had just worn. I bought a replacement switch and decided to change the switch myself (im not an electrician but DIY'er) as i thought it would be fairly simple. I then made a stupid mistake - i turned the electricity off at the main consumer unit and began work and then one of the wires sparked and pop and burnt slightly. It was then I realised that the shower must run off the seperate RCD unit which I didnt switch off :-(

So I then obviously switched the seperate RCD unit off and completed the work and seems to be working on. My question is:

Why did the RCD for the shower not trip? I thought the whole point of the RCD was to trip and switch the power off? I could have had a very nasty shock :-(

Appreciate your help :-)

Title: Re: RCD did not trip
Post by Lectrician on Sep 8^th, 2015, 6:24am

Are you sure it didn't trip? Some trip to half way to force you to switch off and back on. This shows you it tripped, rather than got switched off.

You should have an RCD and fuse or MCB.

The RCD will only of tripped if you shorted live to earth, not live to neutral. It would be the fuse or MCB that would operate on a live to neutral fault, but it would take a good bang to operate that protection, as opposed to the very sensitive RCD.