Sparks Electrical News July 2021

CABLES AND CABLE ACCESSORIES

7

An electrician’s guide to a domestic rewire E lectricians are called upon to carry out many aspects of electrical work, from re- pairing or replacing sockets or light fit-

• Shaving points. • Television aerial sockets. • Hard-wired burglar alarms. • Telephone points. • Data. • Speaker cabling. • Any hidden cabling.

• Light fittings. • Wiring electric fans. • Cookers and extractor hoods.

sure that all circuits are protected and a clear path to earth is in place in the event of a fault within the installation. All new electrical installations are classed as notifiable work, this means that the work must be carried out and/or signed off by a compe- tent person. Rewires, along with all electrical installations or modifications, should be carried out by a compe- tent electrician.

tings to modifications and new circuits, as well as new build and commercial installations. However, probably the least favourite of all is the rewire and, potentially worse still, is the rewire of an in- habited home. Old or faulty electrics can be a serious fire haz- ard, which at worst could lead to injury or electrocu- tion. Not only is old wiring dangerous but it is also not capable of coping with the demands of modern living. If you have been asked to quote for a full house rewire or to perform significant alterations to a home, then the Building Regulations under Part P come into force. When is a rewire necessary? Firstly, you should always meet the client where the work is to be carried out, to get a clear under- standing of what is required prior to completing your estimate of work/costs. You can also at this stage assess the feasibility of the project and de- termine how much to charge. A full rewire should be considered if: • A property is more than 25 years old and hasn’t been upgraded to bring it up to the current re- quirements. • If major remodelling work is required that con- stitutes a material alteration, as defined by the Building Regulations, it is likely that a part- or full rewire of the property will be required. This would include upgrading the consumer unit. • If a property is being extended, or a garage or attic is being converted, this could constitute new work. Therefore, all new wiring will have to con- form to the latest standards. Existing wiring will have to be improved to ensure it can carry the additional loads safely. • If, during a periodic test, it is discovered that the cable insulation readings are below acceptable levels. How to tell if a property needs a rewire A good starting point is to check the type of electricity meter and fuse box (consumer unit). Modern consumer units will have circuit break- ers and residual current devices (RCDs). Old fuse boxes will have old-fashioned rewireable fuses. You can also tell by inspecting exposed parts of the wiring as modern electrical installations are wired using grey or white PVC insulated cable. An indication that a partial rewire has been un- dertaken is if there is a mix of different switch and socket styles and if there is surface-mounted wir- ing running up walls or along skirting boards. What is involved in a rewire? Rewires are messy and are best achieved in two stages, usually before any plastering has been done and at the same time as any plumbing or central heating work. This is also best achieved without any furniture or carpets in place, as ceil- ings and walls will need to be cut into and floor- boards lifted to allow for installation of cables and wiring. The real difficulty will occur if carrying out a rewire in an inhabited dwelling where, apart from moving furniture and lifting carpets, you must en- sure that the first and second fix of each circuit needs to be carried out at the same. This is to en- sure that the power is reconnected every evening for the occupants to have electricity, which can add significant time and expense to any project. Second fix is when switches, lights and front faceplates of sockets are fitted, connected and then tested before being made live. Things to consider during first fix – which in- cludes all of the wiring for: • Circuits and back boxes. • Internal lighting and external security lights. • Outdoor sockets. • Doorbells. • Smoke detectors and heat alarms.

How long will it take? Assuming there are no hidden surprises, a typical kitchen rewire should take two days to complete. A three-bedroom house should take two days to first fix and two days to second fix. Larger properties will take longer.

Second fix involves: • Connecting the consumer unit. • Connecting the geyser, under-floor heating and air-conditioning controls. • Faceplates for sockets and switches.

The importance of earthing Earthing is a vital part of any electrical work to en-

Source: www.tradeskills4u.co.uk

SPARKS ELECTRICAL NEWS

JULY 2021