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Clarity On BS 7671 Amendment 3 Regulation 421.1.201 Metal Consumer Units

Can a plastic style consumer unit be fitted in a detached garage or shed / out-building?

Yes, providing a risk assessment is carried out to say that, in the event of a fire, flames would not spread to the main dwelling. Carrying out a risk assessment is fundamental in this instance.

Do fire retardant glands and trunking have to be used?

No, providing the IP integrity after the installation is maintained, which is IP4X on the top and horizontal surfaces, and IP2XC everywhere else. However, the use of fire retardant glands and trunking is not precluded.

Do intumescent pads and strips have to be used when installing a metal consumer unit?

No, unless they are provided with the consumer units by the manufacturer. The use of them is not pre-cluded.

Can a plastic consumer unit be fitted if it is enclosed in a steel enclosure?

Yes, providing the IP integrity is maintained after the installation and meets the requirement of regulation 132.12 (accessibility of electrical equipment).

Do metal blanks have to be fitted for unused ways within a consumer unit?

No, there is no provision to use metal blanks. However, if they are supplied by the manufacturer of the consumer unit then they must be used.

Can additional circuits be added onto an existing plastic style consumer unit?

Yes, providing the consumer unit is in good condition. However, do check for the consumer unit for cracks, or any other sign of damage, such as scorching, as it may need replacing.

Can a metal consumer unit be used on a TT System?

Yes, you have to ensure the supply tails enter the enclosure through an appropriate means to prevent damage to the insulation around the conductors. It is also important to tighten the tails that go into the incoming device within the consumer unit to the recommended torque settings, as set out by the manufacturer. Ensure the tails are fixed and secured so as to prevent disturbance.

What coding is given to an existing plastic unit in good condition in an electrical inspection report?

If a consumer unit is located under a wooden staircase or in a passage way which is the sole route of escape then a coding of C3 would be logged. In all other situations no coding is required.

When installing a metal consumer unit, does the metal lid that covers the protective devices have to drop down?

No, providing the consumer unit is of all steel construction and has been tested to BS EN61439-3.

Do all factory fitted connections have to be checked?

Yes, ensure all connections are tightened to the recommended torque settings and also check that polarity of the internal links is correct.

Why the move from plastic consumer units for domestic dwellings?

Most of the fires documented were caused by loose connections that caused excessive heat, resulting in the plastic style consumer unit to loose structure. In most cases these are located under staircases where things such as coats and other flammable products are stored. Once structure is lost, hot components are open to the elements and come into contact with flammable items resulting in a potential fire hazard.