Changing a CU

[Des 56]

Since when has it been a "requirement" to do a test and inspection before a cons unit change ?

Is this by any chance Niceic reg making doctrine rearing its head again?

Also what are these pass and fail certs or notices or whatever else they may be called

 

[PC Electrics]

PC electrics make the case better than me and i agree with his list however just a point to note once the cu has been changed it should be retested. Apologies to pc electrics dont mean to teach old dog new tricks as your list is comprehensive.

agreed

 

[londonlec]

This is why I hate changing CU's.

 

[cogsey133]

[h=1]The new Electrical Installation condition Report which replaced the old periodic inspection report as of January this year. These certificates make provision for aspects of an installation to be classed as unsatisfactory or satisfactory. the new classification system of c1, 2 or 3 are applied c1 being danger present c2 potentially dangerous and c3 requires improvement.[/h]

 

[Guitarist]

Many schemes and publications "recommend" carrying out an EICR before changing a CU so that any problems are flagged-up before the change goes ahead for the very reasons that this post has highlighted.
That said, most electricians will check bonding, have a quick look around and do a 250v insulation test to give some idea of whether the shiny new RCD's are gonna trip.

 

[Des 56]

Just to repeat what I asked earlier
Since when has it been a "requirement" to do a test and inspection before a cons unit change ?

 

[PC Electrics]

Test first, then change CU if good, that makes sense.

I visually checked the bonding (10mm) when i quoted and also tested before CU change.

I disconnected the immersion when i IR tested the circuit with the immersion on it and still go 0M, so that needs to be further investigation

The guy just wants to know what needs to be done, he is ok with fixing what needs doing.

I will give him the news tomorrow

That's new info. It wasn;t in your op. How does the RCD in the new board stay on if this circuit has 0Mohm IR?

 

[markthespark]

I was under the impression that the Installation Cert is for the work that you have carried out ie changed the CU, if he doesnt want the remedial work doing is there any problem just noting that on the cert?

 

[Delboybully]

That's new info. It wasn;t in your op. How does the RCD in the new board stay on if this circuit has 0Mohm IR?

I think there is a load somewhere that we couldnt find (something hidden). A sparky I know once spent a whole day trying to find a similar load and it turned out to be a socket plugged in a wall that had been plasterboarded over, i hope it isnt this bad. Anyway this circuit will need investigating. The owner has only lived in the place a couple of months so there may be something he/we couldnt find by looking

 

[Doomed]

remember that I/R ing an existing installation is fraught with dangers, the neon on the switch fuse spur, the capaciter in that bathroom light fitting, the transformer still left plugged in behind the book case, all sent to confuse and give odd readings.
I know a bloke who wrote off the electronics on an expensive stair lift because it was still connected and he i/r'ed 500V between L and N.

 

[Delboybully]

I am well aware of the dangers of 500v IR. I always IR at 250v first and that was where i got the 0M from

 

[tony mc]

You need to start doing some investigation work now on the cct that is giving you a reading of 0 Meg when IR tested.

As has already been said if you did have a dead short the ocpd would not hold so its likely that a load is still connected.

Start testing by useing your meter on low ohms and see what reading you get. If it is a radial cct it should not take you long to find out roughly where the load is looking at the readings that you get!