Restaurant Kitchen & 3-Phase Oven RCDs

By "bayonet sockets" do you mean something that is only used as part of the oven itself, or a general purpose thing, where later someone could wheel in another 3 phase load and plug it in ?


(BS 7671 stops at the fixed wiring - connectors within an applience or rack are normally covered by product standards - same as you can have live parts exposed inside yuor washing machine, you could have a connector non RCD protected inside a closed box needing a tool to undo.)


The general intention in the current regs is that pretty much anything that is not bolted to the floor needs an RCD, unless there is a very good reason otherwise, though I am aware of 63 A sockets being pressed into service simply to avoid just this rule, that is not normally the best solution.

If fed by SWA or in metal conduit, the RCD could be beside the oven which may or may not help the pain if it trips off unexpectedly, no need to have it in a cupboard miles away.


You could see if there reasonable are grounds for ignoring this - devices that simply have to much earth leakage by design for example, but then there is a need to mitigate the fact that the equipment is single fault to danger if the CPC is broken,  (as the case will be capable of delivering a lethal shock with no second fault needed, as opposed to the normal case where a CPC fault and a live wire inside touching the case gives double fault to danger) In some cases like high leakage equipment, the double fault to danger or better may be restored by having a supplementary CPC paths for example.


Do the oven maker's instructions say that it is or is not OK with a 30mA RCD - maybe do they have a helpline to ask ?

Assume you will need one, until you can show otherwise.

and that if it was used for a specific purpose machinery like in this case it could be excluded.

Has this been removed now? I cannot find anywhere the exclusion for special purpose sockets so I guess it has been removed.

It's changed bit is still there in a way - there is still an option to omit 30mA RCD protection for a socket, but you need to be able to justify its omission and record that in writing - i.e. produce a documented risk assessment.

3phase 32A bayonet plugs & sockets.

I'm not sure what you mean by these (bayonet plugs remind me of the plugs that went into BC lampholders - but no way are they 32A let alone 3 phase!) I'm guessing at a US style rotoloc kind of thing. It's worth checking as if it really should be classed as say an appliance connector it might not fall within the definition of a socket so might give you an easy answer to your problem.


The other approach is to forget the plug & socket arrangement and just hard-wire it. I can't imagine that a 17kW oven is going to be exactly portable.


  - Andy.

Catering equipment is often high risk WRT electric shock due to rough usage, poor maintenance and sometimes doubtful quality. I would therefore be very reluctant indeed to omit RCD protection.

No matter how high standards might be initially, it is likely that a 32 amp socket will be re-used for other equipment within the life of the fixed electrical installation.