18th Edition Consumer Unit Installation Service For Cardiff Home and Business

Your electrical installation includes cabling, accessories and consumer unit (fuse / distribution board) being the brain of the installation. They provide circuit protection, isolation and separation. Older rewire-able fuse boards only protect the cables supplying accessories like sockets, lights and cookers. The offer no protection for a user coming in to contact with a live conductor. It’s the same principle as a plug top fuse; to stop the cable from overloading. Later rcd equipped units provide additional protection. In the event of current leaking somewhere they protect against electrocution and fire. Replacing a fuse board with the latest AMD3 model will help reduce the risk of electrical related injuries.

Older fuse boards like these offer no protection against coming in to contact with a live conductor

Do you need to replace yours? Five reasons customers have a new consumer unit installed:

1. They need a new circuit and their existing fuse board has no spare ways to connect it.
2. They want an electric shower or outdoor socket and have no rcd protection.
3. Fault finding identified a component problem and the replacement part is no longer available.
4. An electrical inspection has advised rewireable fuse boards no longer comply with BS7671.
5. Loft conversion plans state a new unit will be necessary.

What to expect when your fuse board is replaced with a new unit

  • Power for the whole property will be off whilst the work is being carried out. Your telephone line will work but your broadband equipment won’t. Most customers find it’s not the best time to be at home! If your employer allows you to work from home, bear in mind there is no power for broadband equipment and charging your laptop. The process goes something like this:
  • Ensure all sensitive electrical equipment (like computers, hi-fi and televisions) are switched off.
  • Switch the main isolator off to remove power to the fuse board being replaced.
  • Remove the distribution circuit cabling (lights, sockets, oven, shower etc) and test to ensure compliance
  • Remove the existing unit
  • Fix the new unit to the wall
  • Connect the circuits up
  • More tests (prior to energising)
  • Switch the new unit on
  • Live testing and certification

What does an electrician charge to install and certify an up-to-date consumer unit?

The work involved replacing a unit depends on its location, number of circuits and existing wiring. Arriving with a replacement and starting the job means banking on no problems. Many electricians recommend testing prior to fitting the new one. If the circuit tests come back OK the job can begin. If they don’t the customer will know what’s necessary to resolve the faults, or re book if time is an issue. Installing, testing and certifying a new consumer unit in a three bedroom house in Cardiff starts from £350 .

Ten possibilities affecting the cost of replacing your fuse board:

1. Your fuse board is “boxed in”. Box sections may need removing or cutting to allow the replacement enough room and space to work. The latest metal units are heavier, wider and deeper than the previous plastic ones. The hinged door (which needs to remain in place) can add another 100mm of depth. Newer properties have a lot of plasterboard walls and a secure fixing can be another issue.
2. The original wiring isn’t long enough. Supply from the electric meter connects to the main switch inside the consumer unit; either on the left or right. The meter tails are cut to the required length at the time of original installation. If they aren’t long enough; new ones will be necessary to install your new unit.
Wiring for the circuits in your house may need extending. Different manufacturers have circuit protection in different layouts. Extending cables adds time (and the cost of wiring and connectors) to the job.
3. The lighting circuit doesn’t have an earth wire. Most light fittings require an earth connection. If your wiring doesn’t have one; metallic fittings and switches aren’t permitted. This is one of the biggest replacement consumer unit show stoppers.
4. The wiring for the socket circuits isn’t complete. The circuit design for socket outlets requires the wiring to be a continuous ring. This fault is common and can mean additional fault finding is necessary. The options are to find the break in the wiring (sometimes a connection in a socket outlet) or reduce the current capacity of the overload protection device.
5. The main bonding cable no longer complies. Gas and metallic water pipes need a connection back to the main earth terminal. If yours is missing or doesn’t test out OK – it will need updating.
6. The neutral and earth wire for the lighting circuit is one. This needs resolving for electrical safety and to enable rcd fitment. Older rewire-able fuse boards and miniature circuit breakers will not see this as a fault. The later rcd models do and will not stay on as long as this fault exists.
7. The main earth reading is too high. In rural areas the power supply lines enter the property overhead. In these cases you are responsible for your own (safety) earth connection. This is usually in the form of an earth rod outside the property. If the reading is too high it will need resolving prior to installing a new unit.
8. Residual earth leakage. Faulty appliances (and wiring) can allow current to leak (from live conductors to earth). RCDs present in the latest consumer units are designed to trip to protect, older fuse boards don’t see this. High amounts of residual current needs resolving prior to installing an rcd equipped distribution board.
9. Five circuits becomes eight. Often additional wires are added to the circuit protection since the original installation. Replacing the consumer unit is an ideal time to resolve this.
10. The location of your electric meter. Often housed in a small cupboard under the stairs making access difficult, increasing working time.

What options are available for the latest units?

I believe the most important factor is the space available. Ideally the new model will fit in the old location. If it won’t then that is going to take the electrician longer to complete the job and the customer more money.

rcd or full rcbo?
Most circuits in a domestic property have to be protected by a residual current device. When it comes to choosing a new consumer unit the options are to have two rcds so half the installation is protected by each one. In the event of an earth leakage fault the property will loose power to half the installation until resolved. This is the cheaper option. The other option is to have an residual device (called an rcbo) on each circuit. In this configuration in the event of a fault power will be lost for the relevant circuit. This costs more to install although it’s easier to diagnose problems and less inconvenience in the event of a fault.

Paperwork? What paperwork is that then?
Make sure whoever installs your new consumer unit will provide certification. You should receive an electrical installation certificate and building compliance. Anyone on the competent person register will be able to do this. Without it you might come unstuck in the event of an insurance claim or if you decide to sell.

New consumer unit with old wiring?
Cable manufacturers claim the wiring used inside domestic buildings is good for twenty five, thirty years. Older cable often tests out OK although a lot depends on how it was installed in the first place. It’s common to replace a fuse board with the older red and black twin and earth wiring when everything else is OK. If you are concerned about the age or condition of the wiring then an electrical inspection (or EICR) is designed to check that out.
If you have a new consumer unit and it’s tripping my rcd article may help you troubleshoot it yourself.

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