Di i need to rewire this shop completely?

Question

I need write a clear recommendation, not a report, to the owner. Certain information is:
The cables are all PVC/PVC imperial size.
The protective devices are all BS3036 semi - enclosed fuses,
Many existing cables are surface - mounted and within touching distance of the people using the shop,
There are a number of long trailing extension leads,
The supply is three - phase, four - wire and the earthing system is TN-S.
Beside:
1. There is a freezer in this shop with existing 7/044 twin cable, which is considered to be too small. A design has been carried out and the new cable will be a 10/4mm squares twin+c.p.c cable. The cable is to be installed within the fabric of the building, but all current system must remain in place.
2. The local distributor is upgrading its system to a TN-C-S system increasing the prospective fault to 9kA. I want to investigate the appropriate type/s of protective device that might be used giving reasons for my choice/s.

Answer 1

Before you do anything consider replacing the consumer unit with one that is fitted with 30ma RCDs and MCBs. If the imperial PVC cable is in good condition you could consider capping it with galvanised top-hat section. I'm assuming that this is a rented shop and, if so, may be required by law to have a Landlord's Inspection carried out by a qualified electrician and you should get a copy of the inspection report which will give you a list of any faults that the landlord is obliged to undertake repair. This would be at the landlord's expense. Call your local authority Building Control to check this out. Undersize cable is thoroughly dangerous and the inspection will condemn it.

3 phase carries a potential of 415v and is not to played with. If your electricity supplier is going to change the earthing system they would normally carry out the normal range of tests to ensure your circuits were compatible and that your earth potential was the same as theirs.

Answer 2

All electircal cables shoud be iether chased in walls or in metal condit to protect them and the people using the shop, 3 phase cables should in my opinion be at least 4 mm2 as one never knows when he needs to install more electrical goods further more should you find any difficulty you should consult the new E.U regulations regarding cables as even the colours are now changed.

Answer 3

Quite frankly, if you don't know, then you shouldn't be tackling the job.

Answer 4

DID YOU DO THIS AS A ASSIMENT IF SO HAVE YOU GOT THAT ASSIMENT PLEASE EMAIL ME ASAP [e-mail]