RCDs in series

[dgadee]

It appears that in houses RCDs should not be used in series according to my reading of the regulations or if they are one should have a longer trip time. Why do boats use garage ones (which usually have RCDs - why ??) when, I presume, pontoons are protected by RCDs at the supply point? All a bit confusing to me. Any electricians able to explain?

 

[nigelmercier]

I've got three in series in my shed. The one in the house (30mA), then the garage (10mA), then another (10mA) in the shed. Sometimes I trip two of them, no big deal.

 

[dgadee]

Sometimes I trip two of them, no big deal.

Which two?

 

[Graham_Wright]

Which two?

The one on the left and the one by the door.

 

[nigelmercier]

Which two?

The 10mA ones, but only from the shed. They never trip backwards down the chain.

 

[dgadee]

The one on the left and the one by the door.

Tee hee. Those are always the ones that go with me, too.