Consumer Units & Accessories

All consumer units, (in old terms, fuse boards) must now conform to 17th Edition regulations. All consumer units for sale on the Gil-Lec website conform to these regulations. 17th Edition regulations state that all consumer units must be protected against earth leakage with an RCD (Residual Current Device), except for circuits with special requirements such as smoke / burglar alarms. This can be achieved in various ways, and all of these different types of consumer unit are available from Gil-Lec. (See the bottom of the page for a fuller description of the 17th Edition wiring regulations and a definition of RCDs, MCBs and RCBOs).

 

The 4 main ways to achieve 17th Edition conformity with consumer units are as follows:
 

This is the most common type of consumer unit.

The load is split over 2 RCDs, with the Main Switch as the point of complete isolation.

e.g. NHI00631, NHI00571, HAGER VC712C1

 

Advantages

Suitable for domestic dwellings and larger installations

Not prone to nuisance tripping due to the split loads

Lighting can be split to prevent complete loss if one RCD trips

Disadvantages

No provision for specialist circuits e.g. smoke alarms, fish tanks, freezers etc.
 

The load is split over 2 RCDs, with the Main Switch as the point of complete isolation. However, there are extra ways for fitting RCBOs for specialist circuits.

e.g. NHRS15SSLHI, NHRS10SSLHI, HAGER VC818CU, VC710CU

 

Advantages

Suitable for domestic dwellings and larger installations

Not prone to nuisance tripping due to the split loads

Lighting can be split to prevent complete loss if one RCD trips

Provision for specialist circuits

If a specialist circuit trips, all the others stay on

Disadvantages

If a specialist circuit trips, you are not notified by the absence of lighting, as no other circuits will go off.
 

RCBOs provide each circuit with its own RCD protection, with the Main Switch as the point of complete isolation.

e.g NH1104 + RCBOs, VC116 + RCBOs

 

Advantages

Each circuit individually RCD protected

If one circuit trips, all the rest stay on

Provision for specialist circuits

Suitable for all installations of all sizes

Disadvatages

More expensive than other solutions

If a specialist circuit trips, you are not notified by the absence of lighting, as no other circuits will go off.
 

The RCD protects all circuits and acts as the point of complete isolation

e.g NHRS204/63, CED GU563.632

 

Advantages

 - Cheap and small solution

 - Useful for small installations eg. garages (approx. 5 ways max)

Disadvantages

 - Prone to nuisance tripping due to all the load on 1 RCD

 - Loss of all power and lighting if RCD trips

 - No provision for specialist circuits (e.g. smoke / heat alarms)

 

Definitions:
 

An RCD is a module that monitors the incoming and outgoing electric current to protect against electric shocks. If an RCD detects a difference in the current flowing into a circuit and the current flowing out of the same circuit it will “trip” and disconnect the electric supply to that circuit.

 

An MCB is the modern version of a fuse. The added advantage is that when it trips you can reset the MCB rather than having to change the fuse for a new one. MCBs are designed to trip when the circuit they supply draws more current than the MCB will allow. This can be caused by overloading a circuit or by a short circuit.

 

RCBOS are an RCD and an MCB in one. They have the same overload protection as a normal MCB, as well as the added protection that an RCD provides. This makes them a very flexible tool for circuit protection. They can be used to protect just one circuit in consumer units and avoid nuisance tripping to the entire consumer unit.

 

 

All socket outlets should be protected by 30mA RCD in consumer units whether on the ground floor of a house or the top floor of a high rise apartment.

All circuits in rooms with a fixed bath or shower should be protected by one or more 30mA RCDs in consumer units.

All cables buried beneath the plaster surface of a wall or partition (at less than 50mm) should be protected by 30mA RCDs in the consumer units.

All cables concealed in metal stud partitions (common in new builds) should be protected by 30mA RCDs in consumer units.

Installations should be divided up into circuits so as to take account of danger and inconvenience caused by a single fault e.g. such as a lighting circuit.

Installations should be designed and arranged so as to prevent unwanted tripping of RCDs in consumer units.

Safety devices such as smoke alarms should be on independent circuits.