Like for like replacement and MWC

[leep82]

Got a small job to do this week replacing an existing light fitting for a new customer. Im not familiar with the installation so dont know what sort of state it is going to be in. During my conversations with the customer they have asked for a certificate to be completed for the work. I told them that for such work i wouldnt normally issue a certificate as it falls under maintenance, but if that is what they're insisting on, and me
being keen to impress them, then i will go along with there wishes.

My question to you fellow sparks is how far you would go in regards to the testing and certification for such a small job. I have been told that i am unlikely to be able to gain access into the consumer unit other than to lock off the required circuit. With that in mind my plan was to take a Zs reading at fhe existing fitting prior to removal, so as to probe the means of an effective earth, and then once again when the new fitting is installed.

I was going to detail in the comments section my actions and results prior to removing the old fitting and then record my Zs value of the new fitting in the appropriate column. R1+R2 and IR readings i would detail as a limitation. Obviously i would record all other relevant info such as OCPD and type of earthing arrangement, but with regards to the testing have i done enough/not enough?

 

[simpson93]

Is this a commercial property?

 

[Strima]

Minor works. You can do an R2 for dead continuity and also IR at the same time. Zs and any RCD testing if applicable.

Also cursory check of bonding and intake equipment, CU etc to ensure all is good.

 

[leep82]

Is this a commercial property?

Yes it is

 

[simpson93]

Bit funny tho really, they want you to issue a certificate but they won’t let you test.

 

[leep82]

Minor works. You can do an R2 for dead continuity and also IR at the same time. Zs and any RCD testing if applicable.

Also cursory check of bonding and intake equipment, CU etc to ensure all is good.

Would an IR test be practical though? I dont know what else is on the circuit and a small job suddenly becomes that little bigger if i have to start identifying why im getting odd readings.

 

[leep82]

Bit funny tho really, they want you to issue a certificate but they won’t let you test.

Its not that they wont let me test. I think its more about access into the distribution board, permits to work etc etc. I dont have a live working kit and have been told that the installation must remain on, so i can only isolate the circuit i am going to be working on.

 

[simpson93]

If it’s connected to an rcd surely the ir test would give funny readings ?

 

[simpson93]

Its not that they wont let me test. I think its more about access into the distribution board, permits to work etc etc. I dont have a live working kit and have been told that the installation must remain on, so i can only isolate the circuit i am going to be working on.

As I see it you can’t really do your dead tests at all. Just your zs and rcd.

You where quite right in your post that it doesn’t need a mwc but I’m not too sure about doing a half completed mwc.

 

[willy fixit]

N/V Lim

 

[leep82]

If it’s connected to an rcd surely the ir test would give funny readings ?

I dont know what its connected to. The reason for the change is just to modernise an old dirty light fitting, which still works fine. Not due to a fault or anything.

As its currently working with no reported issues i didnt see the need to go down the route of performing R1+R2 and or IR test.

 

[leep82]

As I see it you can’t really do your dead tests at all. Just your zs and rcd.

You where quite right in your post that it doesn’t need a mwc but I’m not too sure about doing a half completed mwc.

I would just comment on the cert why all tests weren't performed. I think these people just want something as a record to say its been done and its ok.

 

[Deleted member 26818]

The 18th edition MEIWC says “where relevant and practicable”.

 

[Toneyz]

We were told once by a scheme area engineer that as a minimum we should do a loop test if it was loads of fittings to put on spreadsheet readings at end of row etc.

 

[simpson93]

1) R1+R2 or R2. 2) Insulation Resistance. 3) Polarity. 4) Zs. 5) RCD if applicable. I have an NICEIC 2392 learning guide, which suggests the essential tests are 3, 4 & 5 (5 if applicable) and if reasonably practicable 1 &2. BS7671 only refers to results of tests, as suggested in the model form App.6



From a thread a while back