rcd tripping on all circuits it supplies..

C

ChrisElectrical88

-

Mentor

Nearly Esteemed

Arms

Joined

Feb 23, 2013

Messages

2,094

Reaction score

1,650

Location

Wales

• Oct 12, 2013

• #2

Could be a faulty RCD? Get there Monday with MFT in hand and practice your fault finding. Unfortunately without it been in front of me that's my best advice.

 

Upvote 0 Downvote

D

Des 56

-

Nearly Esteemed

Arms

Joined

May 6, 2008

Messages

7,665

Reaction score

6,096

Location

Gliese 581C

• Oct 12, 2013

• #3

You have not mentioned that all the neutrals are comoned at the neutral bar

A neutral-earth fault on any circuit has the capability of causing the rcd to trip wherever a load is applied
You need the neutrals parted most likely

 

Upvote 0 Downvote

Lucien Nunes

-

Mentor

Esteemed

Arms

Joined

Jul 2, 2013

Messages

6,778

Reaction score

13,476

Location

London for the time being

• Oct 12, 2013

• #4

Do dead tests first! Prob N-E fault, trips as soon as there is any load to send current back through the faulty neutral and thence to earth.

oops Des too quick for me

 

Upvote 0 Downvote

M

midgetman

• Oct 12, 2013

• #5

There not all tripping out. Mcb is single pole. N - E fault will activate rcd if all mcb are off.

 

Upvote 0 Downvote

C

ChrisElectrical88

-

Mentor

Nearly Esteemed

Arms

Joined

Feb 23, 2013

Messages

2,094

Reaction score

1,650

Location

Wales

• Oct 12, 2013

• #6

Just for the record lads, I had N - E fault in my head. Just didn't put it to words ;-)

 

Upvote 0 Downvote

B

Badged01

• Oct 12, 2013

• #7

If there has been no work done on the CU and its exactly as it was before the problem and the RCD is now tripping with every MCB that is switched on, for me its pointing to an RCD problem -- highly unlikely that every circuit has delevoped a fault all at once. I'd eliminate the RCD from the equation first by replacing with a 'good' one and see if that holds!

If it doesnt hold then you've found something new to me and I await the solution!

 

Upvote 0 Downvote

OP

HappyHippyDad

-

Esteemed

Arms

Supporter

Joined

Dec 18, 2011

Messages

5,277

Reaction score

5,772

Location

Gloucestershire

• Oct 12, 2013

• #8

Des 56 said:

You have not mentioned that all the neutrals are comoned at the neutral bar

A neutral-earth fault on any circuit has the capability of causing the rcd to trip wherever a load is applied
You need the neutrals parted most likely

Click to expand...

So let's say fault is in the ring. You're saying Even with ring mcb off the rcd will trip when another circuit is powered up? How does that work Des as I cant see how you will get an inbalance as nothing will be going through the fault even with all neutrals in same bar? I will be disconnecting all neutrals though as I know you're right, just can't see it!

 

Upvote 0 Downvote

JD6400

-

Mentor

Arms

Joined

Feb 6, 2011

Messages

1,954

Reaction score

742

Location

?

• Oct 12, 2013

• #9

You almost definitely have a N-E fault on one of the circuits , the fastest way to find which one would be to pull the neutrals and reconnect them one by one until the fault reappears . It may be a faulty RCD , but 9 times out of 10 it will be the other .

 

Upvote 0 Downvote

M

micknew

-

Joined

May 28, 2011

Messages

904

Reaction score

514

Location

Kent

• Oct 12, 2013

• #10

The fault current finds its way down any neutral connected to the bar irrespective of whether the MCB's are on or off.

 

Upvote 0 Downvote

OP

HappyHippyDad

-

Esteemed

Arms

Supporter

Joined

Dec 18, 2011

Messages

5,277

Reaction score

5,772

Location

Gloucestershire

• Oct 12, 2013

• #11

JD6400 said:

You almost definitely have a N-E fault on one of the circuits , the fastest way to find which one would be to pull the neutrals and reconnect them one by one until the fault reappears . It may be a faulty RCD , but 9 times out of 10 it will be the other .

Click to expand...

I'm sure you're right JD but have a look at my last post. Cant see where the imbalance would be?

 

Upvote 0 Downvote

OP

HappyHippyDad

-

Esteemed

Arms

Supporter

Joined

Dec 18, 2011

Messages

5,277

Reaction score

5,772

Location

Gloucestershire

• Oct 12, 2013

• #12

micknew said:

The fault current finds its way down any neutral connected to the bar irrespective of whether the MCB's are on or off.

Click to expand...

Of course it does!!!!!!!! You could switch the mcb off chop through the cable and the rcd trips.... this is the same thing!!
Red faced but happy
Cheers all..

 

Upvote 0 Downvote

JD6400

-

Mentor

Arms

Joined

Feb 6, 2011

Messages

1,954

Reaction score

742

Location

?

• Oct 12, 2013

• #13

Edit ; No need for the post now .

 

Last edited: Oct 12, 2013

Upvote 0 Downvote

Richard Burns

-

Mentor

Arms

Joined

Feb 25, 2011

Messages

9,894

Reaction score

5,934

Location

Cambridgeshire

• Oct 12, 2013

• #14

Something like this (this is for two RCDs and an NE fault but shows the current path):

 

Upvote 0 Downvote

M

micknew

-

Joined

May 28, 2011

Messages

904

Reaction score

514

Location

Kent

• Oct 12, 2013

• #15

happyhippydad said:

Of course it does!!!!!!!! You could switch the mcb off chop through the cable and the rcd trips.... this is the same thing!!
Red faced but happy
Cheers all..

Click to expand...

If you clicked on 'thanks' I'd have 5 thanks happydad.

 

Upvote 0 Downvote