Another crimp question

[La Poste]

Greetings.
If I want to wire a standalone RCD underneath the main consumer board I need to take a separate supply to cable to the RCD. I would take this supply from the outgoing side of the main switch in the consumer box. These supply cables would then enter the enclosure of my standalone RCD and act as incomers. I was thinking of using 4mm cable and a 23A RCD.
Is there anything wrong with this method?
Also I was wondering if anyone could recommend crimps I could put on the end of the 4mm cable so that when I bring the cables into the outgoing side of the main switch it is all nice and neat. You know like spade crimps, rather than just shoving the cable into the terminal I think it would look much better and be a better joint too.
Cheers.

 

[keniff]

the only thing i can see is that you would not have a switch to isolate the whole installation, unless theres a main isolator switch on your incoming tails, why not put a 4mm to feed your new rcd from one of your breakers in the existing board or are you a bit short on space?

 

[Graeme Harrold]

Henley block the tails and split before the CU.

 

[telectrix]

best way. perhaps fit isolator in tails at same time

 

[keniff]

yeah, whats everyones view on this one, i was told by an assessor that if you split the tails like this you have to put an isolator on the tails before both consumer units, this is because you should have 1 main switch to isolate the WHOLE installation? i mean i always split the tails like this but not if its one to show on my assessments!

 

[telectrix]

for the extra cost of an isolator before CU and yr new RCD, put one in

 

[ezzzekiel]

Henley block the tails and split before the CU.

as above but drop tails into a isolator first

 

[La Poste]

Ok thanks for the replies.
How about if I have a consumer unit with 100 A main switch.
The tails from the meter go into the 100A switch at the top and at the other side of the switch (the bottom) they come out and go to their repsective RCD's.
Is it OK to just add a phase and neutral wire at the outgoing side of this 100A switch (providing there is room) and drop it down to a small board below.
The 100A switch on the initial main consumer unit would act as the main switch and when in the off position would switch off the whole installation IE both boards.
It is only a small board I want to add with 2 RCD's, both for circuits that run outside the house.
It's a TT system.

 

[nickblake]

You say you want to run in 4mm tails then a 23 amp RCD ,2 things one is whats the over current device for the 4mm tails ,if connectect to a henly / or incomming tails the minimum size should be 25mm , the second thing is dont forget the 23 amp (odd size i ask ) RCD, this rating is the ratimg of the RCD and is not an over current device this you would need an RCBO or MCB and an RCD

 

[La Poste]

Forget the 4 mil I wasn't thinking straight.
I have RCBO's one at 20A for the garage, a radial in 2.5 T E running underground from the house,the cable has been tested and does not need replacing.
The 23 A is still at the property, I need to double check it to make sure it's suitable, I'm pretty sure it's an RCBO.
My idea was to keep the outside circuits separate from the inside.
I like the idea of double pole RCBO's and a small board below the main, I think it will look good and I was just wondering if it's OK to wire it in this way with an extra cable or maybe two coming out of the switched side of the main switch in the board above.
I could split the tails but I am just wiring in two standalone RCBO's and it seems a bit excessive to add another switch and henly block just for these two circuits.
However if my idea is wrong I would be grateful if someone told me.