Domestic buyer Units and Circuit safety Devices - A Glossary

Consumer Units, Circuit safety Devices and Accessories - A Glossary

Consumer Unit

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A consumer unit is the electrical gismo used to distribute power throughout a domestic dwelling. Acting as a safety device, protecting against injury straight through electrical shock, a consumer unit houses safety devices which also safe household appliances from overload.

A consumer unit's first function is the organisation of electrical 'circuits', such that the different ways in which we use electricity throughout the home may be safely and more really managed. A typical domestic installation, for example will have the following circuits: Ring main for power sockets and items like washing machines and Tvs, Lighting, smoke alarms, cooker, shower etc.

Main Switch

This is the 'Double Module' gismo which sits on the far right hand side of a consumer. It ordinarily has a big red bar switch and acts to cut off the entire board. This means that by manual execution it can cut power to every circuit in the installation. Main Switches are practically always rated at 100 amp, allowing it to cut off an installation which pulls no more than 100 amps in total over all circuits.

Mcb

Mini Circuit Breaker. An Mcb protects its circuit against overload. When for example a bulb blows on a lighting circuit the Mcb cuts the power to the that circuit, thus protecting the other lights. No other circuits on the consumer unit have been affected. An Mcb does not safe habitancy against electric shock.

Rcd

Residual Current Devices safe manifold circuits against earth leakage. This is a vital function of a consumer unit as it is earth leakage which causes electrical shock. Rcds quantum the estimate of electricity flowing into the consumer unit against the estimate flowing out. When it detects an inbalance in the middle of the two it cuts the electricity provide to the bank of circuits it's protecting.

It should be noted that this means that a fault on one circuit will succeed in a cutting of the power to any other circuit protected by that Rcd. For example an Rcd may safe the ring main and indoor and outdoor lighting circuits. In this instance a fault on the outdoor lighting circuit will knock out the indoor lighting and all power sockets.

It is for this presume that the 17th Edition Regulations quiz, 'Division of Circuits' to avoid 'Nuisance Tripping'

Rcbo

Residual Current Breaker with Overload (Rcbo). This clever gismo combines the functionality of an Mcb and Rcd and therefore allows for independent safety on private circuits against both overload and earth leakage.

Din Rail

The mounting rail upon which are fitted the Main Switch, Rcds, Mcbs and Rcbos.

Busbar

The gismo which connects electrically the Main Switch, Rcds, Mcbs and Rcbos.

Neutral Bar

The terminal bar which accepts all the neutral wires from the Rcbos and Mcbs.

Domestic buyer Units and Circuit safety Devices - A Glossary

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