Testing before cu change

[richy3333]

The Best Practice guidelines state from the ESC:

7.2. Planned change
7.2.1. The initial approach of the contractor planning the
replacement of a consumer unit should be to
encourage the customer to have a periodic
inspection and test of the installation carried out in
advance of the consumer unit being replaced.
7.2.2. If the customer refuses, a pre-work survey should be
carried out to ascertain if there are any immediate
or potential dangers, or any condition that would
cause unwanted tripping of an RCD, in the existing
installation affected by the change. As a minimum,
the survey should, include:
• making enquires with the user as to whether
there are any known defects, faults or damage,
• an internal visual inspection of the existing
consumer unit to determine, amongst other
things, the type and condition of the wiring
system used for the installation,
• an external visual inspection of other readily
accessible parts of the installation,
• a measurement of the external earth fault loop
impedance, Ze,
• a test of circuit protective conductor continuity
at the end of each final circuit, and
• an insulation resistance measurement of the
whole installation at the consumer unit, between
the live conductors connected together and the
protective conductor connected to the earthing
arrangement.
7.2.3. If any immediate danger, potential danger or
condition that would cause unwanted tripping of an
RCD is found, the customer should be informed that
remedial work is necessary to improve safety.


So it seems that the order of the day is to do as much inspecting and testing as you can before doing any work to assess the current condition of the installation. Have business terms about who pays for what, how and when. State what happens if unexpected faults are found after you have started work - who pays for them etc. Like another post stated, if yo have a copy of the Best Practice with you to back you up, it shows the customer you are a professional and not some numpty that looks at the old board and then says '£300 quid mate'

Personally I think it would be foolish to undertake a CU change without any pre-change investigative inspection and testing if you are a professional. qualified spark.

 

[richy3333]

The Best Practice guidelines state from the ESC:

7.2. Planned change
7.2.1. The initial approach of the contractor planning the
replacement of a consumer unit should be to
encourage the customer to have a periodic
inspection and test of the installation carried out in
advance of the consumer unit being replaced.
7.2.2. If the customer refuses, a pre-work survey should be
carried out to ascertain if there are any immediate
or potential dangers, or any condition that would
cause unwanted tripping of an RCD, in the existing
installation affected by the change. As a minimum,
the survey should, include:
• making enquires with the user as to whether
there are any known defects, faults or damage,
• an internal visual inspection of the existing
consumer unit to determine, amongst other
things, the type and condition of the wiring
system used for the installation,
• an external visual inspection of other readily
accessible parts of the installation,
• a measurement of the external earth fault loop
impedance, Ze,
• a test of circuit protective conductor continuity
at the end of each final circuit, and
• an insulation resistance measurement of the
whole installation at the consumer unit, between
the live conductors connected together and the
protective conductor connected to the earthing
arrangement.
7.2.3. If any immediate danger, potential danger or
condition that would cause unwanted tripping of an
RCD is found, the customer should be informed that
remedial work is necessary to improve safety.


So it seems that the order of the day is to do as much inspecting and testing as you can before doing any work to assess the current condition of the installation. Have business terms about who pays for what, how and when. State what happens if unexpected faults are found after you have started work - who pays for them etc. Like another post stated, if yo have a copy of the Best Practice with you to back you up, it shows the customer you are a professional and not some numpty that looks at the old board and then says '£300 quid mate'

Personally I think it would be foolish to undertake a CU change without any pre-change investigative inspection and testing if you are a professional. qualified spark.

 

[malcolmsanford]

The Best Practice guidelines state from the ESC:

7.2. Planned change
7.2.1. The initial approach of the contractor planning the
replacement of a consumer unit should be to
encourage the customer to have a periodic
inspection and test of the installation carried out in
advance of the consumer unit being replaced.
7.2.2. If the customer refuses, a pre-work survey should be
carried out to ascertain if there are any immediate
or potential dangers, or any condition that would
cause unwanted tripping of an RCD, in the existing
installation affected by the change. As a minimum,
the survey should, include:
• making enquires with the user as to whether
there are any known defects, faults or damage,
• an internal visual inspection of the existing
consumer unit to determine, amongst other
things, the type and condition of the wiring
system used for the installation,
• an external visual inspection of other readily
accessible parts of the installation,
• a measurement of the external earth fault loop
impedance, Ze,
• a test of circuit protective conductor continuity
at the end of each final circuit, and
• an insulation resistance measurement of the
whole installation at the consumer unit, between
the live conductors connected together and the
protective conductor connected to the earthing
arrangement.
7.2.3. If any immediate danger, potential danger or
condition that would cause unwanted tripping of an
RCD is found, the customer should be informed that
remedial work is necessary to improve safety.


So it seems that the order of the day is to do as much inspecting and testing as you can before doing any work to assess the current condition of the installation. Have business terms about who pays for what, how and when. State what happens if unexpected faults are found after you have started work - who pays for them etc. Like another post stated, if yo have a copy of the Best Practice with you to back you up, it shows the customer you are a professional and not some numpty that looks at the old board and then says '£300 quid mate'

Personally I think it would be foolish to undertake a CU change without any pre-change investigative inspection and testing if you are a professional. qualified spark.

That is what they are

 

[richy3333]

Yep and someone wrote them for a reason?

And it could also be argued that BS7671 is also a guideline but we all adhere to it?

 

[malcolmsanford]

And if you can prove that your standard of work is comparable or better than the BS 7671-2008 then you have no need to follow them.

I have proved on many occasions that I never needed to before I started to change a CU, do a a full of set of tests in order to facilitate a that change.

I agree with a lot of which the guide said, try and do a PIR,talk to the customer about known defects , visual inspections on the condition and age of the installation, all that I put on my post #29, but I'm not going to do all that testing until I have the CU change confirmed and I'm going to get paid.

 

[SPARTYKUS]

And if you can prove that your standard of work is comparable or better than the BS 7671-2008 then you have no need to follow them.

I have proved on many occasions that I never needed to before I started to change a CU, do a a full of set of tests in order to facilitate a that change.

I agree with a lot of which the guide said, try and do a PIR,talk to the customer about known defects , visual inspections on the condition and age of the installation, all that I put on my post #29, but I'm not going to do all that testing until I have the CU change confirmed and I'm going to get paid.

Malcolm! I agree!

if you want to sing from another hymn sheet fine

I've just been lucky. I've always been fortunate enough to be able to do a full PIR before changing the Consumer Unit. So it's never been an issue. It was part of the job.

 

[malcolmsanford]

Malcolm! I agree!

if you want to sing from another hymn sheet fine

I've just been lucky. I've always been fortunate enough to be able to do a full PIR before changing the Consumer Unit. So it's never been an issue. It was part of the job.

Long may it continue for you son, as you are perfectly correct doing a full PIR is so much preferable, but sure as eggs are eggs, one day someone will say no, even if just out of badness, and then you have to decide what will be your best course of action.

 

[SPARTYKUS]

saying all that I forgot to mention I have only ever changed one fuse box (in my house)







Just kidding (done two)

 

[T&Earth]

Hi Guys
Some very interesting points made, I've never changed a on its own its always been during a rewire! What tests apart from Ze, PFC what other test should you carry out / record on EIC form?
Any Help would be most welcome
T&E

 

[telectrix]

if you look at a schedule of results, last page of EIC, all boxes should be filled. i.e. test everything that's there for each circuit.

 

[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.