Aircon unit on separate 20a circuit, via outdoor RCD?

[Skyhigh]

The question is:
Is having an air con unit being fed by a supply that goes through an outdoor IP66 RCD-socket unit against any regs?

--

Long story short, we moved into a new house and it appeared the air-con unit in the conservatory was dead.

Turns out it does work - it's actually on a separate 20a circuit from the consumer, which runs as an armoured cable buried around the side of the house to the conservatory.

The cable goes to an outdoor IP66 single-socket-with-RCD-switch, it passed through this IP66 unit and enters the conservatory.
It powers another single (no RCD) socket on the other side of the conservatory.
It also feeds the air con unit.
(Turns out the RCD just needed resetting as it had tripped)

Mains sockets in the conservatory are on the downstairs mains supply.
Lights are on the downstairs lights supply.
Only the outdoor sockets and aircon unit are on this 20a supply.

I'm aware that due to the power fluctations of an aircon unit, depending on how hard it has to work, it may trip the RCD (or at least, that's what I've read).



Cheers!

 

[DrJimFranklin]

Putting kit like AC units on RCD's is poor design. They are no designed for use of that type of equipment, well the ones you find in the equipment being used anyway. If there was a need to put an AC unit on and RCD due to increased shock hazard caused by the environment it was installed in then you would as a bare minimum use a Type S RCD, but in reality if the increased shock hazard is such that it requires an RCD then one must question the wisdom of installing in the first place.

The AC unit is a piece of fixed equipment..it should be on it's own dedicated circuit.

 

[ban-all-sheds]

The cable goes to an outdoor IP66 single-socket-with-RCD-switch, it passed through this IP66 unit and enters the conservatory.
It powers another single (no RCD) socket on the other side of the conservatory.
It also feeds the air con unit.

Neither the A/C unit nor the other socket will be RCD protected, as RCD sockets do not extend their protection downstream - they protect their own socket outlet and that's it. In the USA you can get GFCI sockets which do provide downstream protection, but not here.

So....

(Turns out the RCD just needed resetting as it had tripped)

What have you really got in the way of wiring accessories and protective devices for the appliance?

I'm aware that due to the power fluctations of an aircon unit, depending on how hard it has to work, it may trip the RCD

Shouldn't do - "power fluctuations" don't create an imbalance between line and neutral currents.

 

[ban-all-sheds]

The AC unit is a piece of fixed equipment..it should be on it's own dedicated circuit.

Why?

 

[bernardgreen]

If there was a need to put an AC unit on and RCD due to increased shock hazard caused by the environment it was installed

RCDs with a 30 mA trip setting do not protect against electrical shock, they will only reduce the duration of an electrical shock if the shock current is high enough to trip the RCD.
The prime reason for installing an RCD is to remove the power if there is an earth leakage current that is large enough to cause a hazard but not large enough to trip the MCB or melt a wired fuse.

 

[Skyhigh]

Neither the A/C unit nor the other socket will be RCD protected, as RCD sockets do not extend their protection downstream - they protect their own socket outlet and that's it. In the USA you can get GFCI sockets which do provide downstream protection, but not here.

This is fine, but it seems when the RCD has tripped or I press 'test', there's no downstream power. Reset the RCD and it comes back on.

I could have been clearer on the RCD - it appears to be a double-pole like this one:
http://www.maplin.co.uk/p/ip66-rated-weatherproof-rcd-protected-outdoor-socket-13a-a86nf

(Turns out the RCD just needed resetting as it had tripped)

What have you really got in the way of wiring accessories and protective devices for the appliance?
Aside from the RCD (if applicable), just a modern consumer unit with RCD.

Shouldn't do - "power fluctuations" don't create an imbalance between line and neutral currents.

I read around a lot to try and find the answer before posting - this came up a few times on various forums as a potential issue. If it's wrong then that's good to know

 

[DrJimFranklin]

Skyhigh, a socket, RCD protected or not, is not designed to act as a fault current disconnection device...BAS is correct to challenge that point you made that you have now re-iterated.

The AC unit should not be fed from the output side of the RCD.. effectively the live socket terminals because this is outside the manufacturers intended use, it is dangerous and the RCD is not designed for this type of equipment.

 

[Skyhigh]

To be honest, I've had the lot switched off at the consumer as it seemed very bizarre.

I'll get someone out to remove the outdoor socket(s) and replace with a IP66 connector so its on its own circuit completely.