Hi Guys,
This is a bit of a long post, as I'd like to detail everything, and take input from others.
Let me start by saying that I did my electrical apprenticeship in Australia, completed all additional courses to become a Licensed A Grade Electricial, as well as a Registered Electrical Contractor. These are required there to be self employed. The wiring rules as a whole are virtually identical, with a few differences, particularly regarding earthing, and the use of Ring Circuits.
When I returned to the UK, I immediately booked in for 17th Edition, and recently did 18th Edition. These to familiarize myself with local requirements. So on the whole, I consider myself a sufficiently trained in these areas.
So, on to the dilemma I have.
I have been asked to wire up a supply to a Wireless Internet Communications cabinet. Generally this is easy, as its nothing more that a standard install. Where this differs is the customer wants to use Rectivertors. For those unaware, they are power supplies, charging batteries and an invertor taking power back to mains voltage. In other words a very fancy UPS.
Again, a standard installation, however the complexities come from the fact that the customer wishes to use a generator and renewables as methods of charging. The rectivertor has multiple modules, each which as far as I am able to determne has power inputs isolated from any other. Each would, however share the chassis ground. Now the generator needs to be earthed and I imagine the generator neutral bonded so that any protective devices will trip should a fault develop.
Now to add the third level of complexity. The output is effectively a segregated supply, but at 240V level. Ground and neutral are isolated from one another, and it is this supply which will be supplying teh electronics used by the communications equipment. This equipment includes network switches, routers and power supplies for radio devices.
So, to recap, I technically have three seperate supplies, each with its own earth and neutral. My understanding is that to prevent nuisance tripping, the neutral from the mains and the neutral from the generator must be isolated from one another. That wouldn't be a problem, but if earths are then bonded together so that RCD's will operate correctly, then neutral being bonded to earths are also connected.
I have been through 551 of the regs over and over again, and I still cannot see anything definitive. If I was in Australia the answer would be simply a matter of sinking three earth stakes, one for the incoming mains, one for the generator and one for the segregated output. You see in Australia a DNO earth is not provided, therefore every property sinks their own earth rod, and bonds the neutral to that earth at the main switchboard, at a point called the MEN ( Multiple Earthed Neutral, multiple because every property bonds the neutral which would be common, to earth).
I'd like input of how you think I should approach this. The Aussie option seems the best one, and provided that this complies with 551, then I can go ahead and install it. Obviously no earth stake at the DNO supply.
I look forward to hearing from any and all.
Thanks in advance
Steve
This is a bit of a long post, as I'd like to detail everything, and take input from others.
Let me start by saying that I did my electrical apprenticeship in Australia, completed all additional courses to become a Licensed A Grade Electricial, as well as a Registered Electrical Contractor. These are required there to be self employed. The wiring rules as a whole are virtually identical, with a few differences, particularly regarding earthing, and the use of Ring Circuits.
When I returned to the UK, I immediately booked in for 17th Edition, and recently did 18th Edition. These to familiarize myself with local requirements. So on the whole, I consider myself a sufficiently trained in these areas.
So, on to the dilemma I have.
I have been asked to wire up a supply to a Wireless Internet Communications cabinet. Generally this is easy, as its nothing more that a standard install. Where this differs is the customer wants to use Rectivertors. For those unaware, they are power supplies, charging batteries and an invertor taking power back to mains voltage. In other words a very fancy UPS.
Again, a standard installation, however the complexities come from the fact that the customer wishes to use a generator and renewables as methods of charging. The rectivertor has multiple modules, each which as far as I am able to determne has power inputs isolated from any other. Each would, however share the chassis ground. Now the generator needs to be earthed and I imagine the generator neutral bonded so that any protective devices will trip should a fault develop.
Now to add the third level of complexity. The output is effectively a segregated supply, but at 240V level. Ground and neutral are isolated from one another, and it is this supply which will be supplying teh electronics used by the communications equipment. This equipment includes network switches, routers and power supplies for radio devices.
So, to recap, I technically have three seperate supplies, each with its own earth and neutral. My understanding is that to prevent nuisance tripping, the neutral from the mains and the neutral from the generator must be isolated from one another. That wouldn't be a problem, but if earths are then bonded together so that RCD's will operate correctly, then neutral being bonded to earths are also connected.
I have been through 551 of the regs over and over again, and I still cannot see anything definitive. If I was in Australia the answer would be simply a matter of sinking three earth stakes, one for the incoming mains, one for the generator and one for the segregated output. You see in Australia a DNO earth is not provided, therefore every property sinks their own earth rod, and bonds the neutral to that earth at the main switchboard, at a point called the MEN ( Multiple Earthed Neutral, multiple because every property bonds the neutral which would be common, to earth).
I'd like input of how you think I should approach this. The Aussie option seems the best one, and provided that this complies with 551, then I can go ahead and install it. Obviously no earth stake at the DNO supply.
I look forward to hearing from any and all.
Thanks in advance
Steve