Dual RCD

[mort2376]

there is no reg in BS7671 stating this

514.11.1
A durable warning notice must be permanently fixed in a clearly visible position to identify the appropriate isolating devices, where equipment or an enclosure contains live parts which cannot be isolated by a single device.

If the 2 gang 2 way for up and down stairs is fed from 2 mcbs/rcbos then this applies.

 

[Fleeting]

Not sure I agree with this. I have seen plenty of multicore swa cables supplying different circuits.

If you followed the BBB to the letter then the upstairs and downstairs 2 way switches need a lovely yellow sticker on if supplied from 2 circuits and I don't see that happening.

I believe what he should have stated was  conductor and not cable.

 

[Andy™]

514.11.1
A durable warning notice must be permanently fixed in a clearly visible position to identify the appropriate isolating devices, where equipment or an enclosure contains live parts which cannot be isolated by a single device.

If the 2 gang 2 way for up and down stairs is fed from 2 mcbs/rcbos then this applies.

if you turn off the main switch, which is an isolator, then condition met since its isolated by a single device. doesnt say they cant be on different circuits

 

[mort2376]

But not always practical!

 

[kerching]

I suppose, in theory, the single Pole MCb/RCBO is not strictly an isolator as it only breaks the Live side and the BBB says isolation involves disconnection of all current carrying conductors so that includes the Neutral. Discuss

 

[Fleeting]

If Regulation 461.2 applies which is likely to then isolation of the neutral conductor is not required for TN-S or TN-C-S systems.

 

[Sidewinder]

For final circuits 314.4 applies so therefore no shared N conductors if the lines are connected to two separate breakers.

 

[mort2376]

That's why I only fit DP RCBO's on consumer unit change overs.