minor work certificate


Postby bilko » Sat Jun 25, 2011 2:26 pm

Hi guys,
anyone help me got a blank minor works certificate, on the essential tests section it calls for the max measured Zs,& earth fault loop impedance
how are both these tests acheived! And it also asks for operation of equipment what is this,sorry don't have an electrical background just an intrest,have being doing some home electrics which is due to be inspected
just want to have an insight on certification and what the electricain is talking about.just one final question if i'm changing like for like do i need to fill in a minor works cert
thanks to anyone who can answer my questions
Bilko
bilko
Posts: 2
Joined: Sat Jun 25, 2011 1:48 pm

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Postby ericmark » Sat Jun 25, 2011 8:12 pm

Oh dear you have a lot to learn. Well I will try.

Earth fault loop impedance. The impedance of the earth fault current loop starting and ending at the point of earth fault. This impedance is denoted by the symbol Zs.

Ze That part of the earth fault loop impedance which is external to the installation.

So reading the 17th Edition Ze can be found in two ways. Inquiry i.e. phone up the supplier and ask them. For a TN-C-S they will likely answer 0.35 ohms and for a TN-S they will likely answer 0.8 ohms. The other method is to use a loop impedance meter.

With Zs we can either measure the ohms of the cable supplying the device and add to it Ze or again measure direct with a loop impedance tester.

To measure the ohms we are not allowed to use a multi-meter we have to use a meter which uses at least 200ma to measure with.

We also need to test the time taken for a RCD to trip. One can get a single meter to do all this but more normal to have three meters in a set. To buy about £750 to hire about £75 for week which is normal min time.

There are cheap alternatives you can get a plug in tester which it claims tests all this these Socket & See testers cost around £35 but all they do is give a green light so you have no figures to enter on the form.

Firms like Test4Less offer testers starting at £400 again how good they are I don't know.

But for domestic we are only required to test every 10 years. And likely we can get it done for less than £400 and in 10 years time it will at least need re-calibration and by then there may be completely new regulations.

Really speaking every job should have a Minor works or Installation Certificate. I will admit I often don't bother but I still do the tests. This is the whole problem with DIY in the main DIY people don't want to spend out on test equipment.
ericmark
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Joined: Fri Oct 02, 2009 8:49 pm
Location: Mold, North Wales.


Postby bilko » Sun Jun 26, 2011 4:26 pm

bilko wrote:Hi guys,
anyone help me got a blank minor works certificate, on the essential tests section it calls for the max measured Zs,& earth fault loop impedance
how are both these tests acheived! And it also asks for operation of equipment what is this,sorry don't have an electrical background just an intrest,have being doing some home electrics which is due to be inspected
just want to have an insight on certification and what the electricain is talking about.just one final question if i'm changing like for like do i need to fill in a minor works cert
thanks to anyone who can answer my questions
Bilko


:) Thanks very much for your answer
bilko
Posts: 2
Joined: Sat Jun 25, 2011 1:48 pm


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