Chris Pearson: 
 

Derek Eccles:

Excuse the pun, but I think we have crossed wires. I believe regulation 641.1 is not being complied with and was hoping the IET would agree with me.

I see. It depends, I suppose, what you mean by, “before being put into service”. To the contractor, that may mean handover.

It is always useful when a contract means what you want it to mean - that's why commercial lawyers exist.

My take on this would be, the contractor must comply with the EAWR, which they will do if they comply the IET wiring regulations. For me there is no ambiguity, the contractor must complete all (dead and live) testing before energising anything, meaning there can be no delay between dead and live testing and certainly nothing can be energised in an effort to commission plant.

However I am only one voice in the wilderness, which no-one will listen to. But coming from the IET, now that would be something only the foolish would ignore.

the contractor must complete all (dead and live) testing before energising anything

Unfortunately that's impossible. The system must be energised before performing the live tests … not just by definition but by practicality - the very nature of live tests (e.g. loop tests or RCD functional tests)  requires the supply to be present & connected.

Dead tests alone should be sufficient prove that the system is safe to energise (that's their purpose) - even though the system still might not necessarily be safe to operate under every situation. It's a subtle distinction - for a simple example, if dead tests show OK, it should be safe to connect a socket circuit to the supply - but what you don't know at that stage as you've not been able to test the RCD is that additional protection can be relied upon - so it might not be entirely safe to plug in appliances (certainly not a long extension lead outside to dodgy hedge clippers kind of thing). Once energised the live tests can be performed. It seems to me the big question is still whether “commissioning” is considered as the same sort of thing as live-testing or the same sort of thing as the installation being “in service" - I guess it's somewhere inbetween.

It gets more complicated when bits of the system are outside of BS 7671 scope - or even worse bits that are in scope are fed from bits that are out of scope. Often understanding and inginuity is needed rather that rigid adherence to a paragraph which may or may not be entirely applicable to a situation.

Hopefully what's really intended is testing of a more progressive nature - live testing things as and when it's practical to do so -  while keeping an eye on any residual risks and addressing those by other means (e.g. training) - but at the same time realizing that the ‘milestone’ of all-live-tests-completed might not be completely met until quite a late date.

   - Andy.

Derek Eccles: 
My take on this would be, the contractor must comply with the EAWR, which they will do if they comply the IET wiring regulations.

I disagree. Whilst the note by HSE (on page 13) states that installations which conform to the current BS 7671 are likely to conform to the relevant parts of EAWR 1989, there is more to the latter.

For example, R.14 is concerned with live working. Table 537.4 lists various devices which may be used for isolation, but it does not tell you when to use them. A BS 1363 plug and socket may be used for isolation, but it does not say that if you wish to work on a machine, you should unplug first.

AJJewsbury: 
 

the contractor must complete all (dead and live) testing before energising anything

Unfortunately that's impossible. The system must be energised before performing the live tests … not just by definition but by practicality - the very nature of live tests (e.g. loop tests or RCD functional tests)  requires the supply to be present & connected.

Dead tests alone should be sufficient prove that the system is safe to energise (that's their purpose) - even though the system still might not necessarily be safe to operate under every situation. It's a subtle distinction - for a simple example, if dead tests show OK, it should be safe to connect a socket circuit to the supply - but what you don't know at that stage as you've not been able to test the RCD is that additional protection can be relied upon - so it might not be entirely safe to plug in appliances (certainly not a long extension lead outside to dodgy hedge clippers kind of thing). Once energised the live tests can be performed. It seems to me the big question is still whether “commissioning” is considered as the same sort of thing as live-testing or the same sort of thing as the installation being “in service" - I guess it's somewhere inbetween.

It gets more complicated when bits of the system are outside of BS 7671 scope - or even worse bits that are in scope are fed from bits that are out of scope. Often understanding and inginuity is needed rather that rigid adherence to a paragraph which may or may not be entirely applicable to a situation.

Hopefully what's really intended is testing of a more progressive nature - live testing things as and when it's practical to do so -  while keeping an eye on any residual risks and addressing those by other means (e.g. training) - but at the same time realizing that the ‘milestone’ of all-live-tests-completed might not be completely met until quite a late date.

   - Andy.

It goes without saying live tests require energy. I was hoping to keep the conversation very specific about my particular installation which is completely new, so there isnt anything in or out of scope. 

What the contractor is proposing will lead to unnecessary risk taking and considered by others, more experienced/knowledgeable than me, to be bad practise.

Hi Derek

There is probably quite a lot that is out of the scope of BS7671. The equipment to be powered is classed as “appliances”, and the wiring between them (eg. a VFD and Motor) is something of a grey area for a number of complex reasons. Whilst BS7671 may cover some of the control wiring, this depends on design features that BS7671 may not cover.

This procedure is very much the Main Contractors problem, you may like to ensure that he is aware of it by asking for details of the overseeing design Engineer and commissioning Engineer, and even a method statement as to how he/they is going to carry out their responsibilities. This will undoubtedly lead to a lot of “snag shifting” and you may well be blamed for raising difficulties that are not your responsibility! Such is life, but the legal responsibility for the process (Under CDM) is the Main Contractor. If anything goes wrong it is his problem. Whilst we have many discussions here about “possible” bad outcomes of many things, this is generally just a reflection of general awareness of H&S and the responsibilities of contractors.

For complex installations BS7671 offers general principles, it is impossible to cover all possibilities. Your principle live test is Earth Loop Impedance testing, but if you have RCD protection everywhere (which is unlikely to be at “additional protection” levels for your type of installation) this may well be relatively easy. It becomes difficult once a VFD is in the final circuit, and the need to have the equipment operating normally. Getting the whole control system into the correct state may be very difficult.

You will see from this that the statement you would like is not possible from anyone, even the IET! You could show interest with the main contractor, but I suggest you need a good reason for that interest, and why you think it may not be done correctly, for your own protection. Such could be for procedures for maintenance and periodic test in the future, that may not have been considered at the design stage.

Regards

David CEng etc.

davezawadi (David Stone): 
 

Hi Derek

There is probably quite a lot that is out of the scope of BS7671. The equipment to be powered is classed as “appliances”, and the wiring between them (eg. a VFD and Motor) is something of a grey area for a number of complex reasons. Whilst BS7671 may cover some of the control wiring, this depends on design features that BS7671 may not cover.

This procedure is very much the Main Contractors problem, you may like to ensure that he is aware of it by asking for details of the overseeing design Engineer and commissioning Engineer, and even a method statement as to how he/they is going to carry out their responsibilities. This will undoubtedly lead to a lot of “snag shifting” and you may well be blamed for raising difficulties that are not your responsibility! Such is life, but the legal responsibility for the process (Under CDM) is the Main Contractor. If anything goes wrong it is his problem. Whilst we have many discussions here about “possible” bad outcomes of many things, this is generally just a reflection of general awareness of H&S and the responsibilities of contractors.

For complex installations BS7671 offers general principles, it is impossible to cover all possibilities. Your principle live test is Earth Loop Impedance testing, but if you have RCD protection everywhere (which is unlikely to be at “additional protection” levels for your type of installation) this may well be relatively easy. It becomes difficult once a VFD is in the final circuit, and the need to have the equipment operating normally. Getting the whole control system into the correct state may be very difficult.

You will see from this that the statement you would like is not possible from anyone, even the IET! You could show interest with the main contractor, but I suggest you need a good reason for that interest, and why you think it may not be done correctly, for your own protection. Such could be for procedures for maintenance and periodic test in the future, that may not have been considered at the design stage.

Regards

David CEng etc.

Hi David, thanks for the detailed reply.

In my case, I have a main incoming feeder supplying one large control panel, which in turn feeds about 30 seperate circuits. So the main feeder comes into the control panel, through an MCB, on to busbars which act as the source for the other circuits. One of these is for a pump motor circuit which is quite straight forward. A TPN drop is taken from the busbar common section and fed into a seperate section for the pump motor circuit in question. This section starts with a fuseswitch, followed by a electronic overload and contactor. The contactor tails are connected onto the field terminals in the control panel.

There are 3 seperate cables, which leave the control panel to control, monitor and supply power to the pump. These 3 cables are about 60m in length and run to an above ground local control station. All 3 cables are terminated here. However, the pumps are installed below ground directly beneath the local control station. The pumps are ordered with 10m of cabling for power and monitoring. These 2 cables are brought from below ground level and terminated in the local control station. 

As the control panel has seperate regulations to comply with, I suspect it is out of the scope of the wiring regulations, even though it contains all of the protection equipment ?

I would guess the pump with 10m of cabling must also fulfill certain criteria, meaning it is out of the scope of the regulations ?

Leaving the 3 interconnecting cables between the large control panel and local control station to be inspected and tested ?

Regards, Derek 

Hi Derek

The description is most helpful. I suggest that the BS7671 installation be inspected, tested and a BS7671 certificate issued. At a later date, everything from the controls panel intakes onward be tested and inspected by the commissioning Engineer, and again a test and inspection certificate be issued, although it may not exactly match the BS7671 one. You will then have documentation for everything, and there will be a clear division of responsibility. All that should be simple enough for everyone. If the control panel is to be delivered after the 3 circuits are installed then the supply electrician can install a terminal block at the end of the cables and leave them tested for the panel men. A note on the EIC can explain what was done.

Regards David