Split load CU - cooker and immersion RCD protected?

[iwest]

I know this has come up before, but I was hoping to establish definitively whether a 3kW immersion heater (20 A MCB) and a 4 year old electric cooker (10.8Kw, 40 A MCB) should be RCD protected or not when I get my old CU replaced with a new split load one

thanks!

 

[Spark123]

A 16A MCB will do for a 3kw immersion heater, doesn't need to be on RCD. The cooker doesn't need to be on RCD unless the CCU has a socket outlet which can reasonably be expected to supply portable equipment outdoors. All of this is assuming a TN-S / TN-CS supply btw.

 

[ELZ4742]

lights, imersion, cooker (without skt) and alarms tend to be put on the non rcd side

 

[Sarahspark]

All of this is assuming a TN-S / TN-CS supply btw.

Yes if your supply company do not provide an earth and you have an earth rod (TT system) then the cooker and immersion circuits will at least have to be on a 100mA time delayed RCD

Sarah

 

[Lectrician]

lights, imersion, cooker (without skt) and alarms tend to be put on the non rcd side

Easier to say that any sockets (upto and inc 32amp) that can reasonably be expected to supply equipment used outdoors are to be RCD protected - Anything else can happily go on the non-rcd side. (TN system assumed)

 

[JohnD]

RCBOs are great

 

[securespark]

[Sigh...]

 

[Lectrician]

RCBO's have one down side. When they trip, you don't know if it's due to an overcurent or an earth fault.

 

[securespark]

Cue signal for John to redesign RCBO's to get round this shortcoming & make millions in the process!

 

[JohnD]

I suppose I could make the pods less firmly attached, so you could hinge them apart for testing (?)

edited: Better yet: A little flag that gets poked by the RCD finger when it snaps down to operate the breaker. With a display something like the red/green contact open indicator.

H'mmmm... tooling costs... marketing... finding a business partner... perhaps I can't be bothered. Who needs any more millions?

 

[iwest]

Thanks for the replies, can the immersion go on the RCD side is is that inadvisable?

thanks

 

[JohnD]

it's usual not to.

All the copper pipes are (should be) securely earthed, and it is a fixed appliance inside the house, so not a big shock hazard.

It is also one of the "wet" appliances likely to have a small earth leakage as it gets old, so is prone to cause nuisance tripping, if it is on the RCD.