Isolation of incoming supply for work on the building's wiring

Residential / Commercial/ Industrial properties up 100 amp

If you require the incoming supply to be isolated to allow you to work on wiring we recommend you have an isolating switch installed in the tails between the meter and the consumer unit or main switch. This arrangement will give you flexibility to isolate and restore the supply to fit in with your work programme.

Commercial / Industrial properties 200 amp to 630 amp Low Voltage

In this case it is not normally practical to install an isolating switch and the supply will need to be isolated by removing the cut-out fuses.

To have an isolator fitted or the cut-out fuses removed

The customer will need to contact the supply company that sells electricity to the premises. Each supply company has its own procedures for providing isolation. Normally they will put you or the customer in touch with their preferred meter operator who will have the authority to remove the cut-out fuses, meter terminal covers and install isolators. The supply company or meter operator may charge for this service.

High voltage supplies

Larger industrial and commercial premised are supplied directly from our 11kV high voltage network. The customer will own the 11kV/LV step down transformers, LV distribution system and possibly some 11kV switchgear. To obtain isolation from Central Networks’ 11kV system please contact our Reactive Works section:

Phone 01332 393160

reactiveworks@central-networks.co.uk

To contact the supply company

The name and telephone number of the supply company will be shown on the customer’s electricity bill. However, if you are having difficulty finding out who is the present supplier the customer should phone our MPAS Services Help Line and we will carry out a search on the address to locate the supplier registered for the premises, or please go to our MPAS Services page in the link above.

To contact a meter operator directly

Some meter operators may accept requests for isolation and isolator installation directly from customers and electrical contractors. The Association of Meter Operators web site link above contains a list of meter operators together with their contact numbers and web sites.

Please note: For reasons of confidentiality our MPAS service will need to communicate directly with the customer unless you can provide documentary proof that you are working on his/her behalf. (e.g. a faxed copy of the accepted quotation.)

Central Networks cannot authorise electricians to remove and replace cut-out fuses.

As a Distribution Network Operator, Central Networks does not have meter access rights. We are not permitted to remove meter terminal covers without the permission of the supply company.

Supply Characteristics and Earthing Arrangements

The following typical characteristics are applicable to residential and light commercial/industrial premises for low voltage supplies up to 630 amps. You may find these useful when completing BS 7671 Electrical Installation Certificates.