Shower RCD question

Help Support Talk Electrician Forum:

norv

Senior Member
Joined
Feb 16, 2008
Messages
127
Reaction score
0
Putting a shower into a refurbed office with a Merlin Gerin DB. The RCBO's for this board are

 

norv

Senior Member
Joined
Feb 16, 2008
Messages
127
Reaction score
0
If this is an accepted method there would be no reason why you couldnt RCD any circuit without having to split the tails into a seperate CB/RCD combo.

e.g. say you had to RCD the lighting circuit & you couldnt get an RCBO for the CU or move it onto the RCD side then you could run a piece of 1.5 from the existing CB in the CU, through an RCD next to the CU & then off to the lights.

Ive seen this mentioned on here before but nothing was really said about it (I dont think)

 

The Godfather

Retired
Joined
Mar 24, 2008
Messages
1,302
Reaction score
0
If this is an accepted method there would be no reason why you couldnt RCD any circuit without having to split the tails into a seperate CB/RCD combo.e.g. say you had to RCD the lighting circuit & you couldnt get an RCBO for the CU or move it onto the RCD side then you could run a piece of 1.5 from the existing CB in the CU, through an RCD next to the CU & then off to the lights.

Ive seen this mentioned on here before but nothing was really said about it (I dont think)
My boys don't have an issue with this at all.

Don

 

norv

Senior Member
Joined
Feb 16, 2008
Messages
127
Reaction score
0
Cheers Don & Special Location

Could save some time;)

 
Joined
Mar 28, 2008
Messages
13,618
Reaction score
296
If this is an accepted method there would be no reason why you couldnt RCD any circuit without having to split the tails into a seperate CB/RCD combo.e.g. say you had to RCD the lighting circuit & you couldnt get an RCBO for the CU or move it onto the RCD side then you could run a piece of 1.5 from the existing CB in the CU, through an RCD next to the CU & then off to the lights.

Ive seen this mentioned on here before but nothing was really said about it (I dont think)
Applaud Smiley:)

that the exact point I try to keep saying when people keep moaning about 17ed & RCD an alteration on one circuit..

just waz an extra

 

norv

Senior Member
Joined
Feb 16, 2008
Messages
127
Reaction score
0
The order of connection is irrelevant..they both perform independent electrical functions..

and operate quite independently of each other!

e.g. consider a traditional split load board..

one half has RCD then through MCB's to final circuit & load.

whereas an older Non-RCD board may have had additional RCDs built in for specific alterations that have been carried out..

i.e. whirlpool path RCD off U/S sockets?

Outside socket.. RCD FCU off ring

Or the average home owner with their plug-in RCD adaptor for the lawn mower.

All these have RCD after the circuit breaker.

so as long as you document where it is and all items are clearly labelled and are suitable current ratings for the required load...

then cant see why not?

There is no reason why the supply path to a particular item of equipment cant go through several RCD's / Circuit breakers...

just need to ensure any relevant discrimination is built in to avoid incorrect protective device operating at the wrong time...

same principal as ye ode 'TT' set-up 100ma RCD feeds some MCB's & then also 30ma RCD & further MCB's

as per the old Fig 3a pg 21 OLD O-S-G...

(OBVIOUSLY THIS ARRANGEMENT RATHER SUPERSEDED BY 17TH ED!)
That is some quick thinking & typing Applaud Smiley

 

dan.

Senior Member
Joined
Jun 17, 2008
Messages
274
Reaction score
0
so if using this method (which i thought was frowned upon,but hey ,you live you learn)you dont need a CB in rcd enclosure? its wired direct to the bottom of the RCD without the busbar? this will save me loads of hassle.

 

The Godfather

Retired
Joined
Mar 24, 2008
Messages
1,302
Reaction score
0
so if using this method (which i thought was frowned upon,but hey ,you live you learn)you dont need a CB in rcd enclosure? its wired direct to the bottom of the RCD without the busbar? this will save me loads of hassle.
The OP is suggesting to feed from a 40A MCB, off the Main CU, here Dan.

Again, I can see no problems with the afore mentioned.

Don

 

dan.

Senior Member
Joined
Jun 17, 2008
Messages
274
Reaction score
0
sorry didnt know you could wire the circuit live direct into an rcd.

 
Joined
Mar 28, 2008
Messages
13,618
Reaction score
296
sorry didnt know you could wire the circuit live direct into an rcd.
erm not sure what you mean hear m8?

an RCD has to have live & neutral going through it...

or it wont work..!

RCD could be any where along the path of a particular circuit..

and all of the bits after if will be RCD protected.?

there was that trend at one time for fitting CU's with one RCD main switch..

so your "LIVE" supply tails are direct into the RCD!

the bad part of this arrangement of course is the whole installation trips!! :_|

dosn't really meet the "minimise inconvenience in the event of a fault" bit of the regs!

 

dan.

Senior Member
Joined
Jun 17, 2008
Messages
274
Reaction score
0
ill try explain what im on about.

run a length of 1.5 from original 6 amp CB to incomer side of standalone RCD then run original 1.5 to new RCD ,neutral to neutral bar ,live to load side instead of busbar ,earth to earth bar.

 
Joined
Mar 28, 2008
Messages
13,618
Reaction score
296
ill try explain what im on about.run a length of 1.5 from original 6 amp CB to incomer side of standalone RCD then run original 1.5 to new RCD ,neutral to neutral bar ,live to load side instead of busbar ,earth to earth bar.
Neutral Bar??? ?:|

The RCD has 'Live In' & 'Neutral IN' AND 'Live Out' & 'Neutral Out'....

there is NO neutral bar?

So

assuming your 1.5mm to the original CU had enough spare length..

in principal all you do is cut the 1.5mm

connect the 'IN' side of the RCD to the CU

and the 'OUT' side of the RCD to the load side of the circuit..

maintaining Earth continuity at a suitable connection block / crimp etc..

all other connections at the CU remain the same. :)

 

dan.

Senior Member
Joined
Jun 17, 2008
Messages
274
Reaction score
0
lol @neutral bar its been a long dayBlushing you knew what i meant;)

sounds like its done as i thought,this setup will save me loads of time trying to track down old and obsolete RCBOs in the future.

 
Top