New consumer unit install issue.

[Iona222]

I'm working with my friend a sparky. He changed the consumer unit.

Before hand I checked all circuits for continuity and done quick eicr, everything was OK.

Now with the new board on were getting a neutral fault showing on socket ring. Funny thing is the rcd manual test button isn't working. On the rcd coving the said ring. You think it could be something to do with this why showing a fault on ring. Thank you.

 

[westward10]

Disconnect the circuit completely including the cpcs and try the rcd.

 

[Iona222]

Disconnect the circuit completely including the cpcs and try the rcd.

Disconnect the circuit completely including the cpcs and try the rcd.

OK will do, its the manual test button that not working. What you thinking could be the issue?

 

[westward10]

May be no issue it could be the fault through the circuit causing the rcd not to function correctly.

 

[MJPD29]

I've had a neutral-earth fault cause an rcd test button not to work before. I have no real explanation for it but it prevented the rcd from tripping.

 

[timhoward]

Have you IR tested that circuit, either as part of checks before new board, or since the problem emerged?
Have you tried all circuits off and done an RCD test?
Is it a dual-rcd board - have you tried the circuit the other side - see if the problem moves?

 

[Iona222]

Have you IR tested that circuit, either as part of checks before new board, or since the problem emerged?
Have you tried all circuits off and done an RCD test?
Is it a dual-rcd board - have you tried the circuit the other side - see if the problem moves?

No haven't tried these, will do.

 

[Iona222]

I've had a neutral-earth fault cause an rcd test button not to work before. I have no real explanation for it but it prevented the rcd from tripping.

How did you fix the issue?

 

[Iona222]

The spark extended the cpc to reach the earth bar, he asked me what cpc I had on the van, I got him some off 10mm I had, if this wasn't the correct size would the cause more fault current to go through the the neutral, hence cause the test button not to work properl??

 

[timhoward]

The spark extended the cpc to reach the earth bar, he asked me what cpc I had on the van, I got him some off 10mm I had, if this wasn't the correct size would the cause more fault current to go through the the neutral, hence cause the test button not to work properl??

What do you think?
Don't confuse yourself pal, you have two issues here -
1 - does the RCD work or not
2 - why does one circuit cause the RCD to trip

Sort out number 1 first and get the board happy with that circuit disconnected.
Then move onto sorting out number 2. IR tests are your friend, L+N to E.

 

[Iona222]

What do you think?
Don't confuse yourself pal, you have two issues here -
1 - does the RCD work or not
2 - why does one circuit cause the RCD to trip

Sort out number 1 first and get the board happy with that circuit disconnected.
Then move onto sorting out number 2. IR tests are your friend, L+N to E.

You asked me what im thinking.

The spark has extended the cpc using the wrong size cpc causing more fault current to go through the neutral. Causing the test button not to work.
If I change the cpc to the correct size the fault current will go to earth, the neutral will be what it should be, the test button will work.
Thats what I think.

Thats what ill be doing 1st thing Tuesday

 

[suffolkspark]

If the circuit didnt have RCD protection prior to the board change I would say its likely you missed something on the EICR you said you did prior to the board change (but also mentioned you hadnt done any IR testing in post #7)
Or there's a neutral in the wrong bar

 

[westward10]

Assuming the earthing conductor should have been 16.0 replacing a short section with 10.0 will have a negligible effect. You have a neutral to earth fault on the ring final so why would a reduced earthing conductor change this.

 

[Iona222]

What do you think?
Don't confuse yourself pal, you have two issues here -
1 - does the RCD work or not
2 - why does one circuit cause the RCD to trip

Sort out number 1 first and get the board happy with that circuit disconnected.
Then move onto sorting out number 2. IR tests are your friend, L+N to E.

What do you think?
Don't confuse yourself pal, you have two issues here -
1 - does the RCD work or not
2 - why does one circuit cause the RCD to trip

Sort out number 1 first and get the board happy with that circuit disconnected.
Then move onto sorting out number 2. IR tests are your friend, L+N to E.

Assuming the earthing conductor should have been 16.0 replacing a short section with 10.0 will have a negligible effect. You have a neutral to earth fault on the ring final so why would a reduced earthing conductor change this.

No larger cpc that is required, if you read what I put he's put 4mm cpc on a circuit that should be 1.5mm. Does the cpc not need to be the correct size.

 

[telectrix]

the extended cpc has nothing to do with it. you have a N-E fault on the ring circuit which is inhibiting thr RCD. i don't know the theory behind this but i've had it a couple of times.

 

[DPG]

What IR results did you get for each circuit?

 

[MJPD29]

How did you fix the issue?

Once we found and removed/ rectified the fault the RCD started functioning normally again

 

[Iona222]

Once we found and removed/ rectified the fault the RCD started functioning normally again

I agree, I just spoke to the spark he said he did a I.r. test and its fine.

 

[Iona222]

What IR results did you get for each circuit?

Was over the required 38M it was. Ill go back change all cpc to the correct size. I read this could be the issue.

 

[Iona222]

the extended cpc has nothing to do with it. you have a N-E fault on the ring circuit which is inhibiting thr RCD. i don't know the theory behind this but i've had it a couple of times.

I read that you can get a error from neutral to protective earth if the cpc is oversized.