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Posted By Topic: RCD as main switch - legit?

Feb 04 2018 18:00

Hey Guys of 3000 states that wherever there is more than one final subcircuit requiring RCD protection, more than one RCD must be installed. Does this mean that having an RCD main switch with 2 or more subcircuits is not compliant? It is obviously standard practise to wire up garages and caravans etc this way, and it is how i did it myself until i came across this rule one day. Is there some other rule than supersedes this somewhere? or is it just a rule that people ignore due to the cost of extra rcds and bigger boards/single pole RCBOs?

Also, I was taught as an apprentice, that domestic installations must have a minimum of 2 lighting circuits. Is this the case? or just a misinterpretation of this clause stating they must be on seperate RCDS when there are more than one.


Feb 04 2018 18:08

remember a garage is most likely not the entire installation and is a sub-circuit itself, and a caravan is also not an installation, so your application of this particular RCD rule is incorrect.

Feb 04 2018 20:59

dlink has answered Q1.

For Q2, yes it\'s a mis-interpretaion.

Mar 20 2018 21:15

The RCD in the switching power supply is a type of snubber circuit that is connected in parallel with the switch tube to protect the switch tube. The RC absorption circuit is also used for the same purpose. The RCD clamp circuit used in the flyback circuit is to provide a leakage circuit for leakage inductance energy and also to protect the switch tube. From a functional point of view, both the RCD snubber circuit and the RCD clamp circuit can protect the switch tube from the reverse spike voltage (RCD snubber circuit) or leakage inductance (RCD clamp circuit), which is the same from this point of view.