Any ideas? New CU keeps tipping.

[baileyswalk]

So I've had a new cu installed but I had to move it so a 63A isolator was put in between the metre and the new board. Now we have a problem. The new shower and the main ring are tripping the board as soon as any load what so ever is put on them. I could almost understand the old mains ring having a fault in it but the new shower tripping also seems odd - maybe its a red herring? We do have a couple of sockets bodged onto the CU to get the freezer back in action working fine as well as the new toilet on a separate breaker (saniflow) working fine! Somewhat puzzled to say that least. Any ideas, test suggestions?

 

[DetlefSchmitz]

Exactly what is tripping? What does it say on it?

 

[AndyPRK]

Why did you have to move it?

Usually a neutral wire connected to the wrong neutral bar is the cause. (On the circuit which cause a trip when used)

 

[securespark]

What are the Insulation Resistance readings for all the circuits (you'll find these on the certificate given to you by the installing spark)?

 

[Taylortwocities]

So I've had a new cu installed but I had to move it so a 63A isolator was put in between the metre and the new board.

Only 63A? What is the size of the fuse in the DNO's service head?

 

[baileyswalk]

The circuits are OK. Checked for neutral faults, earth etc. Bother the mains ring and the new shower trip under load. The mains ring will trip under the slightest load (router etc.). Had to move the CU for a new kitchen installation. Its strange that there are two faults on different circuits failing in the same way. Tried getting a 100A isolator for between the metre and the board but 63a was the highest I could get. I'll never draw more than that I don't think anyway, and also its not tripping. Its the individual circuits that are tripping.

 

[baileyswalk]

Also... I was told that the neutral is twinned with the earth or something?? Does this play funny on the CU?

 

[flyingsparks]

So you changed the CU yourself then?
Take some pictures of the inside for is please.
You have the neutrals for those two circuits in the wrong neutral bar.
100A isolator a are readily available and your 63A one is likely to get hot and catch fire. It will not trip on overload. It's only a switch.
Change it. In fact, get someone who knows what they're doing to check the installation.
Did you carry out any testing? What are the results?

 

[Taylortwocities]

The OP said

So I've had a new cu installed but I had to move it

Which would mean that a registered electrician installed the new one
(And it worked OK. Is that correct @baileyswalk??)

then -for some reason - the OP had to move it
(And then this problem occurred. Is that correct @baileyswalk??)




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[Taylortwocities]

Tried getting a 100A isolator for between the metre and the board but 63a was the highest I could get. I'll never draw more than that I don't think anyway, and also its not tripping.

You have to cater for fault conditions, not what you "think" the maximum load might be in normal use. A 100A isolator is about the most common switch you can get.


Isolators do not "trip" they are switches. Or was it, perhaps a switch/fuse? Being used because you have extended the meter tails to the new CU position??

As above, need to see photos of everything, and that includes the isolator.

 

[AndyPRK]

Does the 63a item have a test button?

Pics would help.

 

[JohnW2]

Has BAS not noticed this thread?

Kind Regards, John

 

[Taylortwocities]

 

[baileyswalk]

Spark got it sorted. The CU neutral was wired back onto the wrong rail so it was going back onto itself... Or something. Can post some pics later tho if anyone is still interested.

 

[Taylortwocities]

Cool. There's one every week who does that.

I'm still interested in this mystery isolator though…