Testing before cu change

[ezzzekiel]

cant see what difference it makes either way test and identify faults first or install and rectify faults fter providing customer is made aware of any possible additional costs then it dosent matter.

most faults after a cu change can be corrected in an additional hour or two, unless you happen to be unlucky and hit multiple faults but this tends to be a rarer occasion.

 

[Mfctitch]

Evening Ian

Me again when doing an insulation resistance test of the whole installation would this be done at 250v or 500v ?

Cheers

 

[malcolmsanford]

Evening Ian

Me again when doing an insulation resistance test of the whole installation would this be done at 250v or 500v ?

Cheers

If it was a CU change I would do a L/N joined to Earth at 250v for the whole installation before I disconnected anything and see what you got. If you get a good result and for me that is anything over 50mohm on an old installation then that is good enough for me.

If I got something lower than that, but over 2 mohm I would then as I changed to board do each individual circuit to see which one was giving a lower reading and depending on what I find would dictate what I do.

 

[Mfctitch]

Again thank you for your reply.

Now I don't want to test your Patience too much but is "mohn" the same as "meg ohms"
And what course of action would you take if the readings were lower than 2 mohm.

 

[malcolmsanford]

Sorry yes mohn is Meg ohm just fat fingers.

Well as the GN 3 tell us that anything over 1 meg ohm is acceptable but under 2 meg ohm should be investigated.

Personally unless there is dampness or fault on the cable I don't think I have ever encountered that low of a reading. So I would not be overly concerned if I got 10 Meg ohm, but I would note in the part for next test perhaps a 3-5 yr rather than a normal 10 for domestic.