30ma RCD tripping on TT circuit

[PC Electrics]

Shoot me now but.Went to a house today with a TT system. RCD tripping but not identifiable to a particular circuit. Spent all day trying to identify which circuit was the problem. Each circuit would stay on independently but when other circuits where added, the RCD would trip - tried all combinations. Ended up changing the 30ma RCD to 100ma trip, all sorted.

Absolute nightmare to IT all circuits, clip on current leak tester was useless.

Tell me what I have done wrong ?

:good night:

1. You have failed to meet the requirements of BS7671:2008 by removing an RCD which met those requirements and replacing it with one that does not.

2. You have failed to meet the requirements of Part P of the Building Regulations by leaving an installation in a less safe condition than it was in before.

Did you do an MWC for this work? If you did, get it back and shred the evidence.

If this client should feel in any way dissatisfied with your work and should call your scheme provider....... well, I wouldn't want to be in your shoes.

 

[Andy™]

i get the feeling there isnt a scam provider....

 

[tom1]

[quote name='Andy

 

[Andy™]

if there is then dont they give you the chance to do remedial ?

yes

 

[bluetof]

Thank you for all your comments.

I don't think I explained myself very well. This is a main switch that I am talking about. I don't think it was ever designed to have a 30ma RCD in place - I suspect that it has been changed to a 30ma RCD in error. It is a very large house with stables, lots of outdoor circuits etc.

I have started out on my own after 16yrs working as a maint spark for a company (made redundant). I have done the 17th and 2391 and really pride myself on doing things properly (costs me a bloody fortune).

As for the ' scam provider ' - I am in the process of registering.

 

[PC Electrics]

Thank you for all your comments.I don't think I explained myself very well. This is a main switch that I am talking about. I don't think it was ever designed to have a 30ma RCD in place - I suspect that it has been changed to a 30ma RCD in error. It is a very large house with stables, lots of outdoor circuits etc.

I have started out on my own after 16yrs working as a maint spark for a company (made redundant). I have done the 17th and 2391 and really pride myself on doing things properly (costs me a bloody fortune).

As for the ' scam provider ' - I am in the process of registering.

TT installs require RCD protection - they have done for donkeys. There was no error - and anyway that's not up for discussion. What you've posted here changes nothing.

 

[binky]

Tripping RCDs - just spent 2 days trying to identify cause of rcd tripping on a dual RCD board fitted by me about 10 months ago. Turn off 4 MCBs controlled by RCD, reset unit, turned on MCBs one at a time. RCD tripped on sockets, seemed to be boiler. Removed dodgy FCU and wired boiler to plug. All seems PK so went home. Day 2, fault returns on sockets, then light circuit 1, then light circuit 2, then back to sockets - WTF. Then as time progressed, would trip on lights with Line disconnected at board and operating any light switch. Tested circuits, small issue with sockets, nothing on lights. Repaired socket circuit. RCD still tripping. Plugged in socket tester - 1 light only live-earth reverse WTFeck. Removed what's left of hair, then noticed key meter has no display WTWTfeckfeck To cut long story short, Neutral fault on incoming supply was causing havoc by arcing live to neutral in flat downstairs. DNO called, problem fixed everything back to normal. So moral of story is if struggling to identify fault, go back to basics and start from beginning. Also worth just checking for loose terminal in CU, a frien of mine had his RCD tripping randomly every few weeks - tightened up all terminals in CU and problem went away.

 

[green-hornet]

Thank you for all your comments.I don't think I explained myself very well. This is a main switch that I am talking about. I don't think it was ever designed to have a 30ma RCD in place - I suspect that it has been changed to a 30ma RCD in error. It is a very large house with stables, lots of outdoor circuits etc.

I have started out on my own after 16yrs working as a maint spark for a company (made redundant). I have done the 17th and 2391 and really pride myself on doing things properly (costs me a bloody fortune).

As for the ' scam provider ' - I am in the process of registering.

Thanks for the clarification, and there is no need to Justify your training or experiance regardless of what people may say.

Now we know its the main switch, then I have to agree that you have done everything right, and it should be 100mA and not 30mA.

I would however do some more testing to satisfy myself that there is not an underlying problem which would cause tripping of any downstream rcd's.

 

[steptoe]

to comply with 17th it still most prob needs 30mA protection,

and has been said before, he has left installation in a less safe condition than when he arrived.

sorry, and now you have touched it you MUST put 30mA protection in.

 

[paul b b]

Blue, i think you are thinking of the stype 100ma main switch that TT have installed, i'v not got the regs to hand but, if it was me i would put a 30ma back on as steptoe among others have said you have made it less safe.

 

[green-hornet]

I may have misunderstood more!

The 100mA should be the main switch, circuits downstream would be protected by 30mA RCD's if these are not in place then it need sorting asap, as it would be unsafe.

Looks like someone before tried to justify the use of a 30mA main switch, which is totally wrong.

 

[ianmacd]

Agreed its not as safe/compliant as it was before.

 

[Lurch]

Looks like someone before tried to justify the use of a 30mA main switch, which is totally wrong.

I'd disagree with that as the OP said there are 2 boards, one with a 100mA and one with a 30mA main switch, so basically a split load board for TT but in 2 seperate units.

So far I haven;t seen anything that says whether the main switch in this unit that the OP is referring to should be 100 or 30mA so no-one can say whether the OP is wrong or right, but the OP seems to be a bit lacking in knowledge as there is nothing wrong with using an RCD in place of a main switch for a CU or DB as long as it is suitable.

 

[ianmacd]

I'd disagree with that as the OP said there are 2 boards, one with a 100mA and one with a 30mA main switch, so basically a split load board for TT but in 2 seperate units. So far I haven;t seen anything that says whether the main switch in this unit that the OP is referring to should be 100 or 30mA so no-one can say whether the OP is wrong or right, but the OP seems to be a bit lacking in knowledge as there is nothing wrong with using an RCD in place of a main switch for a CU or DB as long as it is suitable.

Additionally you do not know (none of us do) why it was 30mA anyway. It may well have been to comply with a previous alteration.

Are there any existing certs there?

 

[batty]

I'd disagree with that as the OP said there are 2 boards, one with a 100mA and one with a 30mA main switch, so basically a split load board for TT but in 2 seperate units. So far I haven;t seen anything that says whether the main switch in this unit that the OP is referring to should be 100 or 30mA so no-one can say whether the OP is wrong or right, but the OP seems to be a bit lacking in knowledge as there is nothing wrong with using an RCD in place of a main switch for a CU or DB as long as it is suitable.

First post says he changed 30mA rcd for 100mA which is wrong as some circuits should have 30mA rcd protection I would think.

 

[Lurch]

First post says he changed 30mA rcd for 100mA which is wrong as some circuits should have 30mA rcd protection I would think.

This is what I'm saying, some cirdcuits should have RCD protection, but we have no idea what it is supplying and why so we can;t say whether it os wrong or right. Obviously if you were assuming things you'd assume it was 30mA for a reason, but you know what they say about assuming things.

 

[Andy™]

Thank you for all your comments.I don't think I explained myself very well. This is a main switch that I am talking about. I don't think it was ever designed to have a 30ma RCD in place - I suspect that it has been changed to a 30ma RCD in error. It is a very large house with stables, lots of outdoor circuits etc.

I have started out on my own after 16yrs working as a maint spark for a company (made redundant). I have done the 17th and 2391 and really pride myself on doing things properly (costs me a bloody fortune).

As for the ' scam provider ' - I am in the process of registering.

it may not have been originally designed for a 30mA instead of the 100mA, but the fact still remains that a 30mA is now required, and it was 30mA, but you have changed to it something that is against 7671:2008. you have left the installation in a more dangerous state than when you arrived

and i assume you notified this change to LABC since your not part P reg'd?

 

[tom1]

I'd disagree with that as the OP said there are 2 boards, one with a 100mA and one with a 30mA main switch, so basically a split load board for TT but in 2 seperate units. So far I haven;t seen anything that says whether the main switch in this unit that the OP is referring to should be 100 or 30mA so no-one can say whether the OP is wrong or right, but the OP seems to be a bit lacking in knowledge as there is nothing wrong with using an RCD in place of a main switch for a CU or DB as long as it is suitable.

so one board with sockets and bathroom circuits with 30ma

one board with protected cable for lights, oven ect with 30ma now changed to 100ma?

 

[Lurch]

so one board with sockets and bathroom circuits with 30ma one board with protected cable for lights, oven ect with 30ma now changed to 100ma?

No. One board with 100mA for lights etc... and one board with 30mA for sockets etc, now possibly also 100mA. The OP needs to confirm what is what or just pass the job onto someone who can.

 

[green-hornet]

I have to agree here, we need to know what circuits the 30mA RCD was protecting, and from which board if there are two in the installation.

I think I have confused myself, then even confused others

Changing a 30mA for a 100mA just to stop the RCD from tripping is not a solution, and as others have said could be dangerous.