Minimum tests for a CU change

[m4tty]

Hi,

Been reading the ESC Best Practice Guide on Domestic CU changes and thought id copy some of it out for newbies doing board changes.

Although I always fully test every circuit individually as im quite new heres what the BPG says which I think some newbies may be interested in.

10.2 In addition, as a minimum, the following tests should be carried out to the existing circuits connected to the replacement consumer unit.

- A continuity test of the protective conductor of each circuit, to the point of the accessory electrically furthest from the consumer unit and to each accessible exposed-conductive part.

-A continuity test of all ring final circuit conductors

-A measurement of the combined insulation resistance of all the circuits. The measurement need only be made between the line and neutral connected together and the protective conductor connected to the earthing arrangement.

-A test of polarity and a test to establish earth fault loop impedance (Zs) at each accessible socket outlet and at least one point or accessory in every other circuit, preferably the point or accessory electrically furthest from the consumer unit.

-RCD Tests

10.3 The EIC should identify in the comments section any potential dangers that exist with the reconnected circuits and other defects that exist in the reconnected circuits , and that the installation of the consumer unit has been carried out in accordance with the recommendations in this guide.

Hope this helps someone.

CheersGuinness

 

[revjames]

And if the tests are unsatisfactory?

 

[mikep]

I would suggest that everybody reads this guide as it gives some very useful information.

 

[Doc Hudson]

I would suggest that everybody reads this guide as it gives some very useful information.

Indeed, I find all of the ESC best practice guides well presented, easy to read and very helpful.

Doc H.

 

[sellers]

I agree, ESC guides are very helpfull and actually written with good common sence in mind! Changing a cu and testing at every point is very impracticle in most cases.

---------- AUTO MERGE Post added at 10:34 ---------- Previous post was at 10:26 ----------

And if the tests are unsatisfactory?

10.3 The EIC should identify in the comments section any potential dangers that exist with the reconnected circuits and other defects that exist in the reconnected circuits , and that the installation of the consumer unit has been carried out in accordance with the recommendations in this guide.

It seems by that comment that its ok to reconnect and note down? Which to me works both ways, customer isn't put off having a CU change by you saying extra costs may occurr if faults are found. Installation is generally safer with new board. On the downside you are still reconnecting a dangerous circuit and writting it on the test sheet that the customer will never read. Personally depending on how dangerous it is I would have them get it sorted. I usually allow 3/4 day to do a cu change. If I find any faults and rectify them in that time then its usually in the original price.

 

[Apache]

Have a link gentlemen

http://www.esc.org.uk/pdfs/business-and-community/electrical-industry/BPG6_09.pdf

 

[ADS]

And if the tests are unsatisfactory?

I like this question.

Not that fussed on this answer:

10.3 The EIC should identify in the comments section any potential dangers that exist with the reconnected circuits and other defects that exist in the reconnected circuits , and that the installation of the consumer unit has been carried out in accordance with the recommendations in this guide.

It seems by that comment that its ok to reconnect and note down? Which to me works both ways, customer isn't put off having a CU change by you saying extra costs may occurr if faults are found. Installation is generally safer with new board. On the downside you are still reconnecting a dangerous circuit and writting it on the test sheet that the customer will never read. Personally depending on how dangerous it is I would have them get it sorted. I usually allow 3/4 day to do a cu change. If I find any faults and rectify them in that time then its usually in the original price.

How can you possibly let anything go, regardless of how dangerous it is, you are filling in a 'Scedule of Test Results' accompanying an EIC - the results have to comply.

Not having a go at you Sellers, but at that comment in the guide (which I hadn't noticed before)........

If you tested Zs on a lighting radial and it was higher than the maximum - you just put this on the sheet??

If you tested your Ring Final and the readings showed an interconnection (ring within a ring) - you just note it???

If you IR tested at less than 1 Mohm - you just note it??

For all intents and purposes, as those circuits are connected to your NEW CU, the Test Results have to comply - Surely???

 

[tom1]

this cu was changed with minimum test, ie non, pluss min certs also none.

my pic is not to good so looks better than it is.

quite a bit of copper showing, neutrals and cpc randomly terminated in the bars, except the cooker circuit that one was to short so just was not terminated

 

[Ash]

It's funny, the company I worked for replaced must be over 100 ccus in an area in the last 2 months, not one of them had continuity of bonds and cpcs, every Ze was inaccurate with parallel paths and none had insulation resistance tested even though insulation was falling apart in my hands. One was nearly left with out a main earth conductor because they thought one of the bonding was going down to the meters even though all the properties were TN-S with earth on the armoured right next to the unit.

One didn't even know what TN-S was and thought his Ze reading was too high, then refused to believe me because he's the experience spark and i'm the monkey

Even when I insist they do the tests, "I'm just the monkey trainee", yet I'm the one showing them how to fill out the certs that I refused to be associated with.

sorry, I needed to get that rant out of my system

 

[Larnacaman]

Are you Still Working for this CowBoy outfit??

 

[Ash]

nope, I got out, getting ready to get with a scam because I keep getting local people wanting stuff done from word of mouth.

 

[Andy™]

nope, I got out, getting ready to get with a scam because I keep getting local people wanting stuff done from word of mouth.

correcting all their work is it?!

 

[macu]

Hi everyone,

What would you do if you found some of the conductors within the cu box were short, to enable to terminate?

Thanks.

 

[sparkytim]

EXTEND THEM

 

[Larnacaman]

Just make sure you use GOOD quality insulated crimped connectors. ....Preferably of the heat-shrink type!!!

 

[macu]

Thanks for that.

 

[Ash]

wagos?

 

[Larnacaman]

wagos?

Not very professional to use these in a CU to extend a cable. A permanent means of extending the cable is a far better proposition to my mind....

 

[Apache]

Not very professional to use these in a CU to extend a cable. A permanent means of extending the cable is a far better proposition to my mind....

I would propose that a Wago was a stronger connection on a solid cable than a crimp. You try pulling both apart and see. They are classed as a permanent joint and can be hidden in calls and inaccessible places.

It's progress.

 

[batty]

I would propose that a Wago was a stronger connection on a solid cable than a crimp. You try pulling both apart and see. They are classed as a permanent joint and can be hidden in calls and inaccessible places.It's progress.

Agreed totally with the vet on this I will always use wagos rather than crimps be it in a consumer unit or under floors a much better job A for speed and B for realiability.