Trip switch on consumer unit

[Deleted User]

Back after the new year celebs... been reading the new replies since leaving this thread yesterday. Thank you all for your interest in my thread and the informative comments. FWOR - very sorry for not being clear about the age of the installation which seems to have put you in some deep 'waters'.

Guys - what I find is that if I switch on the socket switch first and then plug in the appliance, the RCD does not cut out; the RCD only trips if I plug the appliance first and then, switch on the wall socket, although, this does not happen on every occasion which makes it rather odd. Can any of you electricians on here explain why this may be the case. I think the problem may have something to do with the 'transformers' which both my 15in LCD TV and laptop are using. When I 'tested' the same sockets with other appliances (using no transformers), the RCD does not trip. Si I think there is something rather odd with these transformers which may be causing some sort of power surge to an already sensitive RCD. Any of you guys agree with this? That being the case, is there anything that an electrician could do?

Myser

One of the power supplies may be faulty?

The combined leakage of both power supplies (to earth) may be causing the RCD to trip, but this is unlikely. It usually takes a few devices on a circuit to cause the total leakage to exceed 30mA.

Are there many appliances on the same ring?

Either way, you need a competant electrician who has PAT equipment to test the circuit and appliances.

zax47

[quote=[Deleted User];49791385] Any of you guys agree with this? That being the case, is there anything that an electrician could do?[/QUOTE]

An RCD (Residual Current Device) doesn't detect power surges, it detects small currents leaking away to earth. If this rises to a level where it could prove a danger to you (more than 30mA, indicating a fault somewhere) then it cuts the power to those circuits it is protecting. The power supplies (not transformers!) for your TV and laptop naturally have a small leakage of current to earth - its just a feature of how they work. It varies as to how much, but if it adds up to more than 30mA then the RCD will interpret this as a fault and trip out.

Normally it is tiny and you would need many devices connected before it added up to more than 30mA and trips the RCD.

So either; a) the RCD in question is being over-sensitive and tripping at too low a level - in which case an electrician can test this and if needs be replace it or b) one of the power supplies has a fault causing it to have to much leakage current and making the RCD trip. An electrian should be able to measure this using the appropriate equipment.

[Deleted User]

zax47 wrote: »

An RCD (Residual Current Device) doesn't detect power surges, it detects small currents leaking away to earth. If this rises to a level where it could prove a danger to you (more than 30mA, indicating a fault somewhere) then it cuts the power to those circuits it is protecting. The power supplies (not transformers!) for your TV and laptop naturally have a small leakage of current to earth - its just a feature of how they work. It varies as to how much, but if it adds up to more than 30mA then the RCD will interpret this as a fault and trip out.

Normally it is tiny and you would need many devices connected before it added up to more than 30mA and trips the RCD.

So either; a) the RCD in question is being over-sensitive and tripping at too low a level - in which case an electrician can test this and if needs be replace it or b) one of the power supplies has a fault causing it to have to much leakage current and making the RCD trip. An electrian should be able to measure this using the appropriate equipment.

Thank you Zax47 for your explanation in terms I can understand. You been very helpful. Looks like I'm going to have an electrician in to sort it out for me as it's getting to be a complete nuisance having to go out in the evening (CU is outside) to reset the RCD.

zax47

[quote=[Deleted User];49793055]Thank you Zax47 for your explanation in terms I can understand. You been very helpful. Looks like I'm going to have an electrician in to sort it out for me as it's getting to be a complete nuisance having to go out in the evening (CU is outside) to reset the RCD.[/QUOTE]

No problem, it shouldn't prove difficult for a half-decent sparky to sort out.

Rabbir1

Agree with above but I would try it without any extension leads or adapters first as they can cause problems, especially if the leads are left wound up or in coils.

[Deleted User]

Rabbir1 wrote: »

Agree with above but I would try it without any extension leads or adapters first as they can cause problems, especially if the leads are left wound up or in coils.

Thanks for the suggestion, but I don't think it would be wise to connect my laptop or the TV for that matter, without the supplied transformers/adaptors. As I already explained, the RCD does NOT trip when I plug in (in same wall sockets)other appliances without adaptors.

Rabbir1

I don't know if the fact that I have adaptors and socket extension cable plugged into these sockets

Extension leads cause an inductive load on the circuit if coiled up.

Myser

Rabbir1 wrote: »

Agree with above but I would try it without any extension leads or adapters first as they can cause problems, especially if the leads are left wound up or in coils.

I think what he means is that if you have the power supplies connected to extensions leads or multi-gang sockets, try connecting them directly into the socket without the extensions.

There is no way you could connect your laptop or TV directly to the mains! You would end up damaging them.