RCD problem

[Julian]

Hi I have a split consumer unit with one ring protected by a 100mA RCD and one ring not. The RCD ring trips out if I switch on any item with high start current plugged into any socket, ie TV, hair dryer, drill etc but is OK with low current devices ie VCR, lamp etc. Now here is the strange thing, it also trips out if I switch on a high current device on the NON RCD protected ring.
I assumed a faulty RCD and being a Saturday pm not being able to buy a replacement I moved all of the sockets to the non protected circuit.
I also assumed if I turned on the electric shower (on the protected circuit )the RCD would trip but it didn't .......... so the RCD seems OK.
This has me totaly confused anyone out there got any ideas?

Thanks

Julian

 

[ban-all-sheds]

I was going to ask if it has it always done this, or if it's new behaviour, but then I noticed that you have a 100mA RCD, which means it's not a new CU, so it must have started recently.

Did you change anything just before this started?

 

[Julian]

No nothing, however the rcd did trip due to a faulty fan heated earlier in the day

 

[il78]

sounds like the two rings have become one or the neutrals are connected incorrectly within your fuse board.......or a pressure fault behind one of your socket outlets......done any decorating lately?

without doing any testing its awkward to say,

try easing the socket faces off and power up to see if it trips and work yourself around the house...its a maybe, and it rule it out...

 

[ban-all-sheds]

Conjoined or switched neutrals at the CU is an obvious suspect, but then it would have been doing this since the day it was installed. And on everything, not just high start current devices. (Not that I'd include a TV in that list).

Talking of high start current, my dad used to have a circular saw powered by a 'kin great capacitor-start motor, that used to take 5-10 seconds to wind up to full speed. Whenever he turned it on, the lights would dim and the TV picture shrink, and then gradually brighten and expand

But I digress.

Julian - when you moved the sockets to the unprotected side, you did move both live and neutral? Again, even if you didn't it wouldn't explain why it was tripping before you moved them.

 

[Extrasolar]

I wired the neutrals from an RCD protected ring circuit in my house to the Non-RCD neutral block by mistake (silly mistake) and the RCD tripped what ever I plugged on. Although The first time I switched it on it didn't. hmm. Make sure your neutrals are wired to the correct block.

 

[Scoby_Beasley]

I wired the neutrals from an RCD protected ring circuit in my house to the Non-RCD neutral block by mistake (silly mistake) and the RCD tripped what ever I plugged on. Although The first time I switched it on it didn't. hmm. Make sure your neutrals are wired to the correct block.

Been there, done that