Fused spur rcd

[dougquade]

I’ve had a water feature installed in my garden, I’ve ran an swa from the garage cu to the water feature area and connected to the pumps rubber flex (wiska box and magic gel used). Although the connections are good, if there is a fault the rcd in the house will trip out. My question is could I install a 13a rcd fused spur in the garage instead of installing a new rcbo CU?
Thanks

Mike

 

[telectrix]

only if you can take the feed from the house off a non-RCD way. does the garage CU have a 30mA RCD ?

 

[Pete999]

I’ve had a water feature installed in my garden, I’ve ran an swa from the garage cu to the water feature area and connected to the pumps rubber flex (wiska box and magic gel used). Although the connections are good, if there is a fault the rcd in the house will trip out. My question is could I install a 13a rcd fused spur in the garage instead of installing a new rcbo CU?
Thanks

Mike

Have you connected the N to the wrong side of the N bar?

 

[dougquade]

only if you can take the feed from the house off a non-RCD way. does the garage CU have a 30mA RCD ?

no rcd non rcd ways. it’s a new build so it’s wired in 4mm T&E to a exterior wall, drilled through and connected to swa feeding the garage so can’t bypass the rcd. Garage has no rcd. Running a separate swa from the cu is out of the question.

 

[Dustydazzler]

unfortunately anything you connect to the garage supply will still trip the house rcd if it gets a fault.
its one of the big disadvantages of having a dual rcd board , you can’t put anything on a seperate Rcbo without having to significantly alter the consumer unit...

 

[pc1966]

As already said, if you cascade two normal RCD you won't get any selectivity. To do so the upstream one need to have both a higher trip value (typically x 3 as RCD can trip anywhere between 50-100% or rating) and a time-delay of a fraction of a second to give the down-stream one a chance to clear a bit overload before the upstream one reacts.

I'm guessing the garage feed (the 4mm T&E mentioned) has a dedicated MCB slot in your house CU? Are you able to get RCBO for that make/model so you could in effect have both the split RCD for your home and a 3rd RCD (RCBO) for the garage and outdoor stuff?

Replacing the MCB with an RCBO would mean a bit of a change though, as it would need to be fed from the live-switched section (i.e. inputs to current RCDs) and not the current RCD output busbar for the MCB, so it is not to be undertaken lightly. I would get a professional spark in to do that.

 

[littlespark]

If it’s a dedicated supply to the garage, then to the water feature, then a few nuisance trips won’t be a massive problem.... unless the garage has freezers or whatnot.

not great practice to have 2 rcd’s in line, but not unheard of.