No matter what field you work in, it is interesting and useful to know how others do it. This is especially true for electrical distribution systems, where standards and practices vary from country to country and even between regions. This tour of a typical British residential electrical panel is a great example of the different ways in which the same engineering problems can be solved, and the compromises that always accompany any design.
We’re used to seeing Big Clive tearing interesting devices to bits, but rest assured that this electrical panel remains largely intact as he reveals its secrets. Compared to the distribution panels and circuit breakers common in North American residential construction, the British consumer unit is a marvel of precision and simplicity. It’s true that the unit on offer hasn’t been put into service yet, and things will no doubt change once an electrician is done with it, but the fact that everything is mounted on a DIN rail is pretty cool. Clive explains some of the panel’s quirks, such as the fact that what looks like a main breaker is actually just an isolation switch, and that there are a pair of residual current devices (RCDs), which we call ground-fault circuit breakers (GFCIs) in North America, which They also don’t work as circuit breakers, despite their appearance. A robust bus bar is provided to connect the RCDs to adjacent circuit breakers, forming two separately protected sets of ground faults.
Clive notes with dismay that the bus bar lugs can actually be inserted behind the riser end of the clamp on the breaker, leading to poor connections and overheating. However, we wouldn’t mind bringing some of these concepts to committees in North America, which we covered a bit in a discussion on circuit protection a while ago.
