Consumer unit change nightmare and some questions

[sambotc]

Thanks Tele, where's the thanks button gone by the way?

So, do you charge a set price for a CU change, and allow a reasonable amount of time for rectifying faults, any thing above and beyond you charge at an hourly rate for example?

Also, what would a low IR reading code as, and also, would have expected the RCD to trip with such a low L-E IR reading 0.09Mohms?

 

[telectrix]

I asked the questions because I like to do things right and by the book (well, except when it comes to the main fuse) and also I am coming across things that i've not experienced before, so although to the book these things are correct,its encouraging to here what other, more experienced members think of the results I have found.

I'm the first one to admit that I don't have much experience in these situations, and unfortunately I'm not in a position to work for free to gain experience off the back of another spark. I'm self employed and as we all know work is thin on the ground at the moment for a lot of people. that said I am not going to take on work that I am not comfortable with, hence asking the questions and hoping that someone can verify my findings and how i dealt with them (rightly or wrongly, happy to receive constructive criticism)

Is suppose the alternative could be just to presume what i'm doing is right and potentially leave a trail of errors for someone else to come and tidy up after me?

no, i think you have approached the problem correctly. even the most experienced sparks can get bogged down sometimes. IMO experience may make you faster, but not necessarily better.

 

[sambotc]

Thanks again, encouraging to know

So just to recap on a question if you don't mind replying:

How do most people carry out continuity testing on lighting circuits? Most of the light fitting weren't pendants so I seemed to take ages messing about with different light fittings taking them apart etc to get to the terminals, really frustrating when the wiring was shoddy, cables coming out of connector blocks etc the loop terminal was often stuffed into the ceiling void etc Is it acceptable to test continuity R1 & R2 etc from the switch itself or will the reading of the switch wires cause inaccurate readings?

thanks in advance



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[johnboy6083]

ive just finished an EICR on a commercial premises, and i too spent absolutley ages fault finding. Theres no hard and set rule on how long it takes. The experience helps when for example seeing a reading to a round figure on IR, 9 times out of 10, it means a load is still connected, determining the way cables are ran, and identifying switching arrangements ect. You have a feel for what you should be seeing, and know if something still complys with a test result, but doesnt seem right ect.

The one thing i beleive is that the inspection is just as important as the test. Youm may have a good reading on a cable ect, but it may be deteriorating badly, and needs remedial work.

Like this:

 

[telectrix]

try using a wander lead and just measure R2. remember to subtract the lead resistance, or null meter with wander lead in circuit. ideal solution for metallic fittings, no dismantling involved.

 

[telectrix]

sometimes the thanks button and like button dissappear if you post simultaneously with anotehr post. do a page refresh and they come back.

 

[johnboy6083]

IMO, with lighting circuits, the only way to do it properly is to test at each point, unless you can see which one is last in line. Even then i beleive sampling is required to ensure that connnections are good ect. As normal, if its bad, then increase the sampling. aking ages to take them apart is part iof the job, and one that the half day PIR's / EICR's probably dont do.

At the end of the day, if that house burns down, you may well be questioned, and could you live with yourself if you didnt test something, even if it wasnt your fault?

 

[sambotc]

Is it standard procedure to carry out a full inspection as well as testing on a CU change? obviously you can't connect a circuit without testing it prior, but I thought the inspection side of things taking off all the socket faces etc would possibly be above and beyond the requirements for a CU change. not to say that it isn't advisable, i'm just thinking of cost etc

Also, tele, how do you calculate or measure Zs without an R1 reading?

 

[johnboy6083]

try using a wander lead and just measure R2. remember to subtract the lead resistance, or null meter with wander lead in circuit. ideal solution for metallic fittings, no dismantling involved.

You still need to check polarity, and the only safe way is either dismantle and test at terminals or using a plug in kewtech type, in which case normal R1+R2 xcan be measured anyway.

 

[telectrix]

Also, tele, how do you calculate or measure Zs without an R1 reading?
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you can't. lighting can be a nightmare with all the different fittings. you also have to bear in mind that anything you dismantle may then introduce a fault, due to being disturbed. a general approach for CU changes is to either do a full EICR first, or just test for bad IR's, shared neutrals and a quick visual, with a rider on the quote that any other faults coming to light will be charged at hourly rate to trace and rectify. makes our job so difficult when joe public thinks a CU change is £50 for the CU from b&q and an hour's labour to install.

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