Trip switch on consumer unit

[Deleted User]

fwor wrote: »

Markings suggest that it's a 30mA RCD, fitted (for some unknown reason - maybe an electric shower elsewhere on it?) just on that spur. 30mA is quite sensitive - IIRC, whole-house RCDs are rated at 100mA, so much less likely to trip.

As you say it's the RCD tripping, there seems no doubt that one or other of the appliances is not as it should be.

One specific question: Does the room where this happen get damp (as in condensation-causing damp)? I've seen a situation - in a garage/workshop - where levels of condensation were so high that the RCD would trip occasionally.

I do have an electric shower, but I don't know if this is also on the ring main. The fact that my oven also goes off; would this imply that it is on the same ring main? With regard to dampness, I doubt this is the cause - 1 socket is in my dining room (TV) the other is in the lounge where I use the socket when I use my laptop. The other socket is in the conservatory - although the socket is on an external double skinned wall, there is no sign of dampness/condensation. Is it possible to change the RCD to 100mA to make it less sensitive?

zax47

fwor wrote: »

Otherwise it would appear to be a very non-standard installation which would not meet current regulations, and should be examined by a qualified electrician.

Cobblers (with all due respect) It sounds like a perfectly NORMAL 16th Edition set up with a 30mA RCD protecting the socket circuits, (and usually cooker & shower) as the 16th edition regs required, and not the lighting circuits. Very STANDARD stuff. A single RCD protecting a whole installation is very frowned upon, and only correctly found as a 100mA unit protecting a TT supply.

However I do often see retrofitted single RCDs ahead of a CU, this practice is no longer allowed as it does not comply with the requirement to reduce the danger from nuisance tripping., That's why splitload boards are put in - with upstairs sockets and downstairs lights on RCD1 and vice-versa on RCD2, with the big loads like showers and cookers spread between then to even out the load. If something trips one RCD then you don't loose everything - you still have some lights and some sockets.

The rules are NOT retrospective in any way - if it safely met the regs in force on installation then that's all it ever needs/needed to do. There is no compulsion to update anything to meet current regs UNLESS you add a new circuit or amend an existing circuit - in which case that work MUST comply with the current regs.

The "transformers" for the TV and laptop are both going to be switch-mode power suplies, that each have an natural leakage current anyway of around 8-15mA. Can easily trip an over senstive 30mA RCD if both are plugged in. Get an electrician in (like me), he can check the RCD is functioning correctly and within the correct limits.

[Deleted User]

fwor wrote: »

The one that's tripping out should not be the main house one. That should be marked something like RCD 80 2 100T.

Otherwise it would appear to be a very non-standard installation which would not meet current regulations, and should be examined by a qualified electrician.

I can't see any switches on the consumer unit marked RCD 80 2 100T. I'm surprised that the installation does not meet current regulations as the CU was installed about 5 years ago by a Part P fully qualified electrician, and he gave me a certificate as proof that the installation meets the regulations. But I think I may call another electrician to check it all out again as this is now giving me some concern.

Thank you for taking an interest in my thread, and may I take this opportunity to wish everyone on this forum a very happy new year.

fwor

zax47 wrote: »

Cobblers (with all due respect) It sounds like a perfectly NORMAL 16th Edition set up with a 30mA RCD protecting the socket circuits, (and usually cooker & shower) as the 16th edition regs required, and not the lighting circuits. Very STANDARD stuff. A single RCD protecting a whole installation is very frowned upon, and only correctly found as a 100mA unit protecting a TT supply.

What I meant was that ~if the whole house RCD is rated at 30mA~ then it would be (pre 16th Edition and) nonstandard. I don't think that's cobblers at all, but you're entitled to your opinion.

Myser

Part P fully qualified electrician

Hmm, I wouldn't necessarily put Part P and fully qualified Electrician in the same sentence!

Can you post a picture of your consumer unit (fuse box).

It seems like you have split load configuration as zax47 mentioned. It wasn't uncommon in 16th edition installations to use an RCD as the main form of isolation and no other isolator. This tends to be frowned upon though.

zax47

fwor wrote: »

What I meant was that ~if the whole house RCD is rated at 30mA~ then it would be (pre 16th Edition and) nonstandard. I don't think that's cobblers at all, but you're entitled to your opinion.

I'm not sure just what you think? Either way If I do happen to see a single RCD protecting an installation (however frowned upon it is - it happens) then its pretty much always a 30mA one - the only exception being a 100mA one correctly used for protecting a TT supply.

What the OP has is very normal for the age of the installation and not at all "non-standard" as you incorrectly suggested.

With all due respect, one of us is a qualified and time-served electrician with nearly 30 years experience, I'm guessing from your comments on this thread that it isn't you......

Rabbir1

fwor wrote: »

The Test button simply simulates a fault on that circuit, and should cause it to trip. But you know it's working anyway.



The one that's tripping out should not be the main house one. That should be marked something like RCD 80 2 100T.

Otherwise it would appear to be a very non-standard installation which would not meet current regulations, and should be examined by a qualified electrician.

RCD 63 2 30T means its a 63A 2 pole 30mA RCD in other words it is rated to carry 63A (it wont trip though as its a RCD and not a MCB) it will trip if it has a earth fault above 30mA. That is the usual type to have in a house with a 60A Main supply fed via underground cable (TNS or TNCS). You would only have a 100mA RCD in a TT system and even then it should be backed up by 30mA RCD's protecting the rest of the installation.

Justicia

[quote=[Deleted User];49764537]I'm surprised that the installation does not meet current regulations as the CU was installed about 5 years ago by a Part P fully qualified electrician, and he gave me a certificate as proof that the installation meets the regulations.[/QUOTE]

Be aware though, lindabea, that the regulations (BS 7671) were updated to a new edition in January 2008 (4 years ago), so it not being being 100% to the current regulations is not that extraordinary. Don't see that only, as a reason for any panic and reason not to trust the work of the electrician In fact, an amendment to BS 7671 is due to be in force from Sunday (I bet that vax47 can't wait :D), so it's not unusual at present to come across an installation that is not fully to the current specifications and yet, is safe for use.

zax47 wrote: »

What the OP has is very normal for the age of the installation and not at all "non-standard" as you incorrectly suggested.

Totally agree - sounds very much like a regular installation of that era, to me.

Rabbir1

I do have an electric shower, but I don't know if this is also on the ring main. The fact that my oven also goes off; would this imply that it is on the same ring main? With regard to dampness, I doubt this is the cause - 1 socket is in my dining room (TV) the other is in the lounge where I use the socket when I use my laptop. The other socket is in the conservatory - although the socket is on an external double skinned wall, there is no sign of dampness/condensation. Is it possible to change the RCD to 100mA to make it less sensitive?

NO. 100mA will not protect you from electrocution.

Justicia

fwor wrote: »

That's a very good point - I was assuming that it was the RCD (the main cutout) which will normally cut all power to the house.

fwor; I have picked up on your wording here, and wonder if this is where the confusion lies?

The "main cut-out" would not normally be an RCD for the average installation - as stated by others above, apart from a TT system (generally rural), the main cut-out is a 100A (typically) dedicated main switch - this is what can remove power to the whole installation, and not an RCD (they would protect particlar circuits with increased risk of shock).