Circuit Breakers

Ian Gardner
Member - 18 posts

It's very important to understand the difference between different sorts of circuit breaker. The plug-in type you use at home on your mower will be a Residual Current Device (RCD), and this is what gives supplementary protection against elecric shock. The other basic type of breakers are Miniature Circuit Breakers (MCB), which are more like resettable fuses.
The two types trip for different reasons.
If your main circuit board is fitted with RCDs (with a trip current of 30 mA), and these are protecting the socket outlets that the cleaners use (or you have socket outlets with built-in RCDs), then you don't need additional RCD plug-in adaptors. However, if the circuit board is only protected by MCBs, then RCD adaptors would be a very good idea.
Note: breakers known as RCCBOs are also available, that combine the function of an RCD and an MCB in one unit. If these are fitted to your main circuit board, you should also be covered.
You may need to get an electrician to advise you on exactly what circuit protection you have installed, and then take it from there.

Graham Kenyon
Member - 39 posts

There's a difference between a "miniature circuit breaker" (mcb) and a "residual current device" (RCD).

The mcb goes in place of a fuse in the electrical distribution board (or "consumer unit" in small premises). It is primarily there to protect against direct short circuits between wires, or between a wire and earth.

The RCD may be:
(a) Included in an mcb (this is called an RCBO) in the distribution board.
(b) Fitted separately in the distribution board or in the fixed wiring installation.
(c) Part of the socket outlet (the ones with the green "test" button).
(d) "plug-in" device that you provide yourself.

The latest Wiring Regulations (17th Edition - BS7671: 2008) that are applicable in a few weeks, will require RCD for most socket outlets for general purpose use, to be part of the fixed wiring.

However, this was not part of a previous version of the Wiring Regulations. It will take some time for all installations to have RCDs fitted because there's no instantaneous requirement for electrical installations to be brought up to the latest "Regs".


So, we can say that the latest recommendation for safety is for you to use RCD for general purpose portable appliances (latest Wiring Regulations). But you should provide one yourself (plug-in type) if you can't determine whether there's one fitted in the fixed wiring installation.

Carl Manning
Member - 11 posts

Going back to the original -is it right or wrong- in a previous post the cleaning business manager instructed a firm to come in and remove all rcds from the scrubbers and other wet activity hardware. I was amazed at her rationale- the cleaners break them too often, if they get a shock they might be awake to do some work! Personally I would rather educate people than HOPE an industrial facility had suitable low level protection. Refreshing take on17th editon requirements, my update suggested aty first that all outlets must have 'push to test' set up; only when challenged by did the presenter agree with the response above- protection of fixed wiring at suitable junctures. I recall one person saying he was leaving early to invest in a company making RCDs! I have since had three queries from H&S Reps asking when RCDs will be fitted to all appliances as required 'by law' - oh how dangerous the internet can be:)

David Price
Member - 80 posts

RCD's are a good idea and for cleaning contractors espically as they don't always get their equipment P.A.T. tested, and I have come across many items used by cleaners that they somehow failed to report to their boss or get replaced.

It is a well known fact that a lot of cleaners do not speak good english, and some cleaning companys take advantage of this by implying that if they break any equipment then they will have to pay for it. So some cleaners use unsafe equipment in the hope someone elae will report it broken.

I make sure that any cleaning contractor provides me with a report every year to say that the equipment on site has been tested and is fit for purpose, I also carryout ad hoc checks myself just to make sure that everything is how it should be.

We have just had the normal 240v sockets in certain areas of the building changed to the fixed RCD type ones and marked for Cleaners Use Only. This was done with the co-operation of the cleaning company, and during a site induction for new cleaners these sockets are pointed out to them, and they are made aware why they are there.

Cleaners just want to get their work done and go home just like the rest of us, but sometimes their safety is not always put first as they know that thay can be replaced almost instantly. Anything that can further reduce the risk of an accident can only be a good thing, but don't always rely on a cleaning company to make the fist move, think what you would like to have in place if you were carrying out the task, and then apply that to the cleaners.