The Consumer Unit – the heart of the home

The Consumer Unit – the heart of the home

By on Oct 13, 2013 in Consumer Unit | 4 comments

THE CONSUMER UNIT is the heart of the home. It distributes electricity to appliances and safeguards the electrical system. With the limited power supplies that are available in Spanish dwellings, it is essential that it is adequately equipped with the correct devices to protect against overloading, short circuits and leaking electricity. 

Back in the day the it was called a fusebox. When circuit breakers replaced fuses it changed its name to a consumer unit. The term consumer unit, or CU, principally applies to domestic premises, and across the Costa Blanca dwellings normally have a 5.75 kilowatt 230 volt single-phase power supply to theirs.

The consumer unit is the heart of the home, and should be treated as such.

It is usually located near the front door and generally consists of two compartments. The smaller compartment is solely for a power control switch (ICP) (however, with the introduction of new Smart Meters this compartment is no longer necessary) which is fitted under an authorised seal fitted by Iberdrola. The larger compartment is for consumer equipment, and houses the safety devices for the subsidiary circuits.

Since 2002 following publication of the latest Spanish electrical regulations, the basic installation for a dwelling requires a consumer unit to be fitted with five sub-circuits. Properties built prior to 2002, can have four sub-circuits, or even only two. Very old properties can be found fitted with only a mains isolator circuit breaker and a Residual Current Device (RCD) without any sub-circuits.

The basic installation is protected by a single RCD rated at 30 milli-amps. This can cause secondary safety problems with loss of lighting and defrosting of food if a trip occurs.

Large properties with higher electrical consumption should have consumer units fitted with additional safety devices. Extra protection is needed for a Jacuzzi, swimming pool, tumble dryer, large air conditioning and heating systems.

For external electrical fixtures and fittings, as well as a pool supply, it is preferable to have them independently controlled in the consumer unit, enabling the sub-circuits to be easily isolated in the event of a fault. This prevents major disruption to the electricity supply inside the property, which may occur during wet weather.

For properties built before 2002 consider replacing the existing consumer unit with a dual split-load consumer unit together with a Surge Protection Device (SPD). By splitting the sub-circuits, electricity will always be present in part of the property if one of the RCDs trips out. An SPD provides protection for the whole house against over-voltage spikes, an occurrence notorious with the Spanish electricity supply.

Consider fitting an emergency light fitting above the consumer unit, especially if it is located in a darkened area. In the event of a power cut the light automatically switches on


  1. Can you tell me if the five sub circuits have to be double pole circuit breakers as I have noticed that you can buy single pole versions not sure if you can use these and if not what would they be used for.

    Mike woodham

    September 4, 2015

    • Yes, all sub circuits in the consumer unit should be protected by double pole MCB’s. Single pole MCB’s can be used downstream in a sub circuit.

      Tony Poole

      September 4, 2015

  2. Thanks for that very helpful,. Can you tell me instead of using a 2 module double pole cb can you use a1 module 1p+N cb like the Schneider IDPN 1P+N instead.

    Mike Woodham

    September 17, 2015

    • 1P+N vs. double pole = same thing. Both switch the live and the neutral.

      Tony Poole

      September 17, 2015

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