RCD and FCU

[Belboz]

Quick one....

If fitting an appliance and MIs state should be fitted with an RCD AND a fused switch, what is the method of wiring??

(a) Mains cable to RCD supply then RCD load to FCU supply then FCU load to appliance

OR

(b) Mains cable to FCU supply then FCU load to RCD supply then RCD load to appliance

Seems to me that the RCD should be 'nearest' the appliance but want to make sure

Thanks

 

[jockspark]

hi i dont know what the set up is on your installation
can you not just use an rcd fcu

 

[Belboz]

Problem is that I have read that RCDs should not be used as switches i.e. the TEST and RESET buttons shouldn't be used as ON/OFF switches.

I have tried to look for a SWITCHED RCD but have had no joy. The only ones I can find are the TEST/RESET button ones.

If anyone has any ideas as to where to source one then great.

If not then I would appreciate the answer to my original post as to what way the RCD and FCU should be wired.

Thanks

 

[Spark123]

Quick one....

If fitting an appliance and MIs state should be fitted with an RCD AND a fused switch, what is the method of wiring??

(a) Mains cable to RCD supply then RCD load to FCU supply then FCU load to appliance

OR

(b) Mains cable to FCU supply then FCU load to RCD supply then RCD load to appliance

Seems to me that the RCD should be 'nearest' the appliance but want to make sure

Thanks

I don't think it will matter all that much, however if you are altering the fixed wiring with concealled cables <50mm in the walls then RCDing the whole circuit is probably the most viable option.
Given the choice of either of the above, I'd go with to top one as those RCD FCUs will probably trip without power applied (active type).

 

[kai]

There is nothing wrong in using an RCD as a switching device - look how many consumer units are available with an RCD as a main switch in them!

 

[Spark123]

Yes, but I wouldn't spec an RCD as a normal functional switch.

 

[jockspark]

i wouldn't spec it but you can use a rcd for isolation ,emergency switching
and functional switching

 

[Spark123]

Bit poor design though imo, had this a while back on another forum - wanting to use MCBs as functional switches. I don't like the idea of a protective device being used in this way.
Much cheaper to break a normal switch than an RCD!

 

[jockspark]

yes i agree just pointing out it can be used table 53.2

 

[RF Lighting]

Surely an RCD switched spur is designed as a functional switch as well though?

OOI, MCBs are also listed as a functional switch now

 

[Belboz]

Thanks for all the replies folks.

I agree that the RCD before the FCU would be better because of the tripping with nothing applied.

I can use the RCD alone using the TEST and RESET as the ON/OFF switch but then the MIs are recommending BOTH FCU and RCD to protect the device.

Seems a shame that, according to my research, a properly switched RCD device does not exist.

Much obliged. At least it genereated some debate!!!

 

[Spark123]

Can you elborate on what the device is? What protection is there on the circuit already, is it RCD protected?
In a nutshell, Yes, you can use an RCD FCU as your isolator etc. But even tho you are allowed to doesn't mean I like it
MCB as a functional switch - not on my shift