RCBO required on an already RCD'd board??

[Diode]

Hi, if I'm using a 17th edition Cu including RCD's, do I need to fit an RCBO for shower circuit? Or simply an MCB?

 

[SPARTYKUS]

Hi Diode, with the greatest of respect, why do you ask?

 

[Johnny-G]

If a circuit or appliance that requires RCD protection already has RCD protection then there is no need to fit any more RCD protection, easy eh?

 

[Diode]

I thought it was overkill and wondered what u guys thought. Thanks

 

[KevinS]

This is such a basic question that I wonder if you are in a position to be doing this job

 

[rich.250]

You should never fit two devices in series that have the same tripping characteristics. Be them Rcd's or CBs
(Or other forms of OCPD alternative to CBS)
This is to prevent two devices operating in the event of a fault, it should be the nearest device to the fault that operates first.
Hope this makes sense.

 

[Dan23584]

It is an odd question

 

[kingeri]

What would be the point? And as said, you need to allow for discrimination. I assume the RCD present already is a 30ma, not 100?

 

[Dan23584]

Even if it was 100mA I'm sure you would need an s-type for discrimination? I think that is right anyway.

 

[SPARTYKUS]

I thought it was overkill and wondered what u guys thought. Thanks

Hi
Hard
to comment as cannot see your exact situ, but if you mean placing a 30mA RCBO in series with the existing RCD in your dual RCD board, then yes, it is overkill. And also a bad idea as you have two RCD devices in series with no discrimination.

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I thought it was overkill and wondered what u guys thought. Thanks

Hi
Hard
to comment as cannot see your exact situ, but if you mean placing a 30mA RCBO in series with the existing RCD in your dual RCD board, then yes, it is overkill. And also a bad idea as you have two RCD devices in series with no discrimination.

 

[rich.250]

Even if it was 100mA I'm sure you would need an s-type for discrimination? I think that is right anyway.

Yes, you would.
Even if you think purely for testing reasons.
30ma times 5, (x5 test for when using the 30ma for additional protection) is 150ma!!
Lol

 

[Amp David]

Overkill you say, i'd say damn right daft

 

[londonlec]

Dear lord.

 

[Megavolt]

Am sorry but time to call an electricia in if your asking stuff like this electricity kills you know :angelsad2:

 

[netblindpaul]

Unless you require redundant protection, which is not a requirement of BS7671.