**CU Changes And YOU**

[Snapester]

When you guys go around to see a CU change and you carry out the test to check the installation before quoting work, do you have the customer disconnect all appliances when doing the IR tests checking for connections between L+N, as i have had problems with shorts showing on circuits because of certain items plugged in?

 

[robsparky1975]

Must be things plugged in somewhere perhaps L&N - E would be a good option here,ive had a borrowed neutral circuit recently on a board upgrade.

 

[Snapester]

Yeah, we'll checking for borrowed neutrals is easy enough but checking interconnections on ring finals with IR tests and get bad readings from plugged in items! Is a ball ache, and asking customer to unplug everything is equally a ballache! But in long run could save hrs!

- - - Updated - - -

Yeah, we'll checking for borrowed neutrals is easy enough but checking interconnections on ring finals with IR tests and get bad readings from plugged in items! Is a ball ache, and asking customer to unplug everything is equally a ballache! But in long run could save hrs!

 

[Poorle]

Hi Jason,

Thanks for the information on CU changes. I have been asked by a mate to look at his electrics. Situation is: a CU has been moved and was hanging off the wall, all circuits bar the boiler circuits removed. Flat been renovated and all cables from the existing circuits cut and left sticking out the floor boards. Owner wants all cables extended and put back into the existing CU - which has no RCDs on it. Flat has been plastered / painted and he doesn't want any damage to plasterboard or paintwork.

Would you extend these cables in junction boxes?

Would you recommend a new CU? - this one doesn't have RCD protection on any of the circuits...

 

[Octopus]

Hi Jason,

Thanks for the information on CU changes. I have been asked by a mate to look at his electrics. Situation is: a CU has been moved and was hanging off the wall, all circuits bar the boiler circuits removed. Flat been renovated and all cables from the existing circuits cut and left sticking out the floor boards. Owner wants all cables extended and put back into the existing CU - which has no RCDs on it. Flat has been plastered / painted and he doesn't want any damage to plasterboard or paintwork.

Would you extend these cables in junction boxes?

Would you recommend a new CU? - this one doesn't have RCD protection on any of the circuits...

New CU is the only way and how many cables need extending?

 

[Pete999]

Good advice many thanks

 

[Poorle]

New CU is the only way and how many cables need extending?

Thanks. All existing circuits need to be extended (around 12 cables). The cables have been cut off, none are labelled up so it's difficult to check what cables are for what circuit.

To check for a ring circuit I tried pairing up the cables one at a time and checking for continuity between lives but found none. Bit stuck..

 

[robsparky1975]

In this instance i would take a socket off for instance and do a backward continuity test,so R1 & R2 test back to the board just to help indentify or indicate circuit/s.Have had to do simliar,didnt take much longer than a standard test anyway as i dont take whats written on old boards as gospel only an indication of what it may or may not supply.Having a helping hand to do the running about would cut the time down a bit.

 

[bigbob]

Always done a full EIC stating that no new circuits or points have been installed, test results given for existing circuits are for information only.
I was told a couple of years ago by my area engineer that this was wrong, and i should not include test results for circuits I had not installed.
The next year the same area engineer asked why I had not included test results on an EIC and advised to take a look at the ESC guidance notes. I had also issued a full PIR, as not fully testing the existing install just feels wrong.

 

[Poorle]

In this instance i would take a socket off for instance and do a backward continuity test,so R1 & R2 test back to the board just to help indentify or indicate circuit/s.Have had to do simliar,didnt take much longer than a standard test anyway as i dont take whats written on old boards as gospel only an indication of what it may or may not supply.Having a helping hand to do the running about would cut the time down a bit.

Thanks, i did that and got readings of between 0.85 - 2.75ohms on all sockets connected to that ring -which is pretty high don't you think? Might be time to calibrate the fluke i bought recently!

 

[STONEZZZ]

Good luck....

 

[KeenaStewart89]

exceptionally helpful post as this is the thing that i am going to do as my first employment my sibling has two Ccus one part stack one wylex fuseboard and it was carried out by a purported electrical technician. the new ccu is part stack half secured half not.

 

[jonny705]

Just seen this interesting thread, and have in the past put and rcd board in and found out their is a nicked neutral in up/down lighting circuit!
Also have had faults on some bodged in ringmain that trips rcd out, and other than taking it out and putting it on its own non-rcd breaker, because if the house is nicely decorated/laminate floors the client dont want to know!
I have always come to the conclusion, if i have upgraded the earthing ,fitted a new board with rcd protection, normally replacing an old rewirable, even if their is one circuit that isnt rcd protected , its still safer/ better than when i started.
But have always worried, a little, as always assumed that when you fitted a new board, any circuit that you connect to said board is your problem , but have never been sure legality wise, plus if the client dont want the upheavel potentiallly , or normally to pay you extra for fault finding, what ultimatly can you do?

 

[davesparks]

That's why you test the installation before removing the old board, so that you can get the faults sorted before replacing it.

 

[Pete999]

What Davesparks said

 

[Deleted member 72666]

What pete says about dave's post.

 

[Leesparkykent]

What pete says about dave's post.

What Stan says about pete's post lol

 

[Rebmltd]

Thanks, very useful information

 

[Breeze]

Chaps,

After reading several posts, threads etc about CU changes and what you are responsible for, i thought i would clear a few things up for those that are unsure.

Now, this affects anyone changing a CU to bring an installation up the current standard, which of course is BS7671 2008.

Now, the following are RECOMMENDATIONS and not set it stone, but its what i normally try and do, which can save a lot of time and trouble.

If you have been asked to price and change a CU, for whatever reason, you should ALWAYS carry out a site survey before any costs are discussed.

Now, once onsite consider carrying out the following:

1- Main Earth Bonding.

i) Is main earthing present?
ii) If so, is it adequate?
iii) IF not include this in your quote as this MUST be up to current standards.

2 - Visual Inspection

i) How old does the installation look?
ii) Are there broken accessories?
iii) Is there evidence of any additions or alterations, good or bad?
iv) Ask the client of any known issues or problems in the past.

3 - Quick Basic Check & Tests

i) If convenient, isolate supply and take off the CU cover
ii) Evidence of additions or alterations?
iii) Carry out IR test between Earthing bar & Neutral bar at 250V


If everything looks ok then you are good to go, BUT, whatever happens, make sure you draw up some form of basic contract that highlights the fact that the quote does not include putting anything un-forseen right, and that if there are problems found during or after, then they may need to be rectified at additional cost.

Now, if there are issues with an installation that are not considered unsafe, although not to current BS, (unearthed lighting circuits excluded), you ARE NOT generally required to put these right, although they should be noted on the cert in the correct box.

4 - Certification.

There is a little confusion about what cert should be issued, of course, after a PIR is carried out.

The way i do it is, if i do a CU Change a full installation cert is issued, noting any deviations.

On the same cert any circuit additions or alterations can also be noted, so there is no need to write out multiples.

If you are just altering circuits with no CU change, then a separate minor works must be issued for each circuit altered.



Also, once you have changed a CU, carried out all the tests, you DO NOT become responsible for the entire installation - just the CU change.

This must be noted on the cert & periodic inspection label that MUST be fitted after the change with the words - "CU CHANGE ONLY".

Hope that helps, and if there any E&O's then let me know.

Good luck - As most CU changes need it

Thanks jason brilliant post. My only problem is you would hope everyone on here trading would already do this as to be deemed competent at there job

 

[shanky887614]

Thanks jason brilliant post. My only problem is you would hope everyone on here trading would already do this as to be deemed competent at there job

just my two cents but i would use an electrical installation condition report rather than installation cert or it looks like you installed it