Crabtree offer a valuable insight into what to look for when specifying or installing a consumer unit to ensure that all the correct standards are met
First of all, it’s important to look at the issue of the inbuilt safety of a consumer unit. Look for a fully insulated busbar with permanent factory fitted non-removeable insulation, and not a consumer unit that has removable sleeving or detachable covers. Permanent busbar insulation brings guaranteed levels of personal protection and reduces the risk to the installer when live working is unavoidable e.g. during testing.
In addition, the selection of a busbar system that includes socket apertures for plug-in devices (MCBs and RCBOs) will ensure guaranteed factory quality connections as standard, as there will be no screws to tighten on the incoming side of the devices, meaning the connection is assured and the risk of installation error during installation is reduced.
Facilitating installation
Instantly completed plug-in connections are easier and faster, so overall installation time can be reduced by using quick fit, plug-in devices. Anything that saves installation time is of value to the installer as saving time means saving money. Installation that is simplified and made quicker can help control costs which in-turn aids quotes, the overall price of the installation and profit margins.
Using plug-in devices also helps with upgrades, additions and repairs, which can be carried out more easily and more securely, unlike products where the entire busbar has to be removed from a complete row of devices to allow an extra device to be added or replaced. A design like this allows installers to add, upgrade or replace a circuit without disturbing any of the connections to the other circuits in the consumer unit – meaning adding in a circuit or carrying out repairs is quicker and safer. This can be a very important consideration for those specifiers who look at lifetime costs.
A consumer unit where the busbar is positioned beneath the DIN-rail allows DIN-rail devices such as bell transformers, timers, contactors etc, to be positioned adjacent to the MCBs and in any position that is required. The busbar remains unchanged, fully intact and insulated, unlike those units where the installer has to cut-off exposed live parts to install a small DIN device.
A plug-in system also provides a fixed positive location for the devices, ensuring that they don’t move along the DIN-rail once they are plugged into position. A DIN-rail clip is useful as it gives added fixing security that keeps the devices locked in position. It may seem a minor point, but when MCBs drift along the DIN-rail it makes it harder to fit the lid and slows overall completion times.
A raised busbar position is important to allow bottom entry cables to be routed under the DIN-rail to the upper section and the terminal spaces, which is ideal when wiring in this way. In addition, there should also be hidden open cable access points on the rear of enclosures to enable flush cable entry, and removable cable access points on the sides for surface wiring – the cut-outs being designed to match surface mounting mini-trunking requirements.
Providing benefits
Crabtree’s Starbreaker consumer units include insulated or metal enclosures (one or two row metal enclosures) and skeleton units for use in existing enclosures e.g. Mantel or Bristol cabinets. The range of consumer units also meets the requirements of the 17th Edition such as Main Switch, Split Load, Hi Integrity, and Dual RCD.
They are available as either fully assembled, ready to install consumer units, or in component format for bespoke assembly on-site. In the fully assembled versions incoming devices and RCDs are already fitted, wired and connected when the board is delivered. Plug-in mains devices utilise much less interconnecting wiring and allow more wiring space for the installer.
To further assist in specifying the best option for a particular installation, Crabtree has also published a Starbreaker consumer unit catalogue that provides designers, installers and employers with more than ten good reasons to specify (see above).
Electrium
T: 01543 455 000
