Generator Installations and EIC issue

[SgtTrojan]

Hi Chaps,

I have a few grey areas in my brain regarding the completion of the EIC for two generators we have just installed. Generators 1 and 2 installed to individual changeover panels in a building. Totally separate installations.

1) Supply characteristics:

a) Earthing arrangement - single core connected to MET of installation so TN-S? Should the generator have it's own earthing too?
b) PFC and Ze. It's a back up generator but considered the source of supply so how do you get around this? It can't run just to test at the changeover panel.

2) Particulars of the installation

a) Means of earthing - Distributors facility as the generator is earthed via the MET?
b) Main protective conductors - None seem to apply

3) Schedule of inspections
This should only relate to the generator feeds right?

4) Schedule of Test Results
The DB information at the top is not applicable. Circuit details will all relate to the single core AWA we installed. One row per singe core.


Thanks in advance.

 

[westie101]

You must have separate earthing for the generators.
Take account of the situation where work is being carried out by the DNO at or close to the service termination, earthing gets disconnected with generators running!

 

[ricicle]

Did somebody design the system and not think to include a generator earth nest

Did somebody design the system and not include the earth impedance/fault impedance of the generator to ensure that all protection in the installation would still function correctly

Sounds like a fairly substantial job to be overlooking these.

 

[SgtTrojan]

Yeah, I assume the designer/ client. In terms of the EIC though it's our responsibility. I'm a bit concerned now though!

 

[JohnW2]

Yeah, I assume the designer/ client. In terms of the EIC though it's our responsibility. I'm a bit concerned now though!

I'm a bit confused. If you installed these generators, your responsibilities are surely not quite as limited as you imply - and, in particular, not limited to deciding how to complete the paperwork. Do you believe that the installation you undertook was/is safe and compliant with the relevant regulations?

Kind Regards, John.

 

[SgtTrojan]

Yes. They did the cable calcs, supplied the generator and provided a specification for us to base our price on. So the construction and inspection and testing element is our responsibility.

If this was a simple, "install that 1mm ² cable for that 10kW shower" then alarm bells would be ringing and this is a new installation and reliance is placed upon the correct design.

 

[JohnW2]

Yes. They did the cable calcs, supplied the generator and provided a specification for us to base our price on. So the construction and inspection and testing element is our responsibility.

I still wouldn't think an installer can hide too much behind an 'acting under orders' (from a designer) argument. It sounds as if you've probably installed generators with an unacceptable earthing arrangement. If a designer had told you to completely re-wire a house but, say, to omit any main bonding, or to use 2.5mm² cables for the main bonding, would you have obeyed those 'orders'?

Kind Regards, John.

 

[SgtTrojan]

Of course not, which is what I just typed above. Knowledge is the only thing missing here (and the generator earthing it seems lol ). They seem to think the 185mm ² earthing conductor back to the MET is fine. Is this not the case?

 

[JohnW2]

Of course not, which is what I just typed above. Knowledge is the only thing missing here (and the generator earthing it seems lol ). They seem to think the 185mm ² earthing conductor back to the MET is fine. Is this not the case?

I'm no expert on this but, as westie said, I think the generators must have their own earth electrodes, and not be reliant on the supply earth (no matter how fat the earthing conductor). As westie said, the supply earth may well be absent at the very same time, and for the same reasons, as the generators have to be fired up.

Kind Regards, John.

 

[JohnD]

I thought big generators instructions specified earth spikes or tapes?

 

[JohnW2]

I thought big generators instructions specified earth spikes or tapes?

I would be very surprised if they did not come with such instructions, and would be equally surprised to find someone installing them who didn't understand the earthing requirements.

Kind Regards, John.

 

[Simon35]

Yes. They did the cable calcs, supplied the generator and provided a specification for us to base our price on. So the construction and inspection and testing element is our responsibility.

I still wouldn't think an installer can hide too much behind an 'acting under orders' (from a designer) argument. It sounds as if you've probably installed generators with an unacceptable earthing arrangement. If a designer had told you to completely re-wire a house but, say, to omit any main bonding, or to use 2.5mm² cables for the main bonding, would you have obeyed those 'orders'?

Kind Regards, John.

Fairly typical in industrial installations, set of cable schedules and termination schedules are provided to the installer to work to. I wouldnt expect the installer to check the design.

 

[JohnW2]

Fairly typical in industrial installations, set of cable schedules and termination schedules are provided to the installer to work to. I wouldnt expect the installer to check the design.

Are you talking about an 'installer' who is a 'qualified' electrician? If so, do you think a qualified electrician who installed something which was unsafe to the extent of causing injury or death would be 'safe' (legally and otherwise) provided that (s)he could demonstrate that (s)he had done exactly what a designer told him/her to do?

History tells us that 'acting under orders' defences are often not successful! One also would hope that a 'qualified' electrician would not blindly obey dangerous 'orders'.

Kind Regards, John.

 

[Simon35]

Fairly typical in industrial installations, set of cable schedules and termination schedules are provided to the installer to work to. I wouldnt expect the installer to check the design.

Are you talking about an 'installer' who is a 'qualified' electrician? If so, do you think a qualified electrician who installed something which was unsafe to the extent of causing injury or death would be 'safe' (legally and otherwise) provided that (s)he could demonstrate that (s)he had done exactly what a designer told him/her to do?

History tells us that 'acting under orders' defences are often not successful! One also would hope that a 'qualified' electrician would not blindly obey dangerous 'orders'.

Kind Regards, John.

On a large installation, hundreds of cables, would you expect the installation contractor to take responsibility for a design they have had no part in?

 

[JohnW2]

On a large installation, hundreds of cables, would you expect the installation contractor to take responsibility for a design they have had no part in?

No, I wouldn't necessarily expect that ... but nor would I expect an installer to do something which they believed was wrong, particularly if they considered it to be dangerous, just because they had been told to do it - and I don't think a court would, either.

Having said that, in the case we are discussing, the OP tells us that he is responsible not only for installation but also for the inspection and testing, which rather shifts the goalposts. How can one meaningfully 'inspect and test' if one does not have a good understanding of the design, and of the design requirements? Indeed, the OP's original questions illustrate this problem, don't they?

Kind Regards, John.