3-RCD consumer unit 15 ways or more?

[dhutch]

I would almost say for outbuildings have the cable not rcd protected, but protected the sockets locally is better, in terms of it tripping locally not back at the house, And assuming its SWA all the way your have your protection sorted.


Daniel

 

[JohnW2]

I would almost say for outbuildings have the cable not rcd protected, but protected the sockets locally is better, in terms of it tripping locally not back at the house, And assuming its SWA all the way your have your protection sorted.

Indeed - unless , as I said, it's a TT installation, in which case I think one really needs an 'upstream' RCD to provide adequate fault protection.

Kind Regards, John

 

[EFLImpudence]

OP -
I would just say that you seem to have a slight misunderstanding on the requirement for RCD protection.

Whilst it may be said in regulations that certain circuits and sockets must be protected by an RCD, the circuits and sockets themselves do not benefit.
The RCD is for the protection of persons using them or mistakenly drilling or nailing into them.

So, if the cable from house to the outbuildings is armoured then an RCD is not required nor necessary - the reason for using armoured cable.

 

[JohnW2]

Whilst it may be said in regulations that certain circuits and sockets must be protected by an RCD, the circuits and sockets themselves do not benefit. ... The RCD is for the protection of persons using them or mistakenly drilling or nailing into them.

... except, as I've been saying, in the case of a TT installation, when an RCD is the only way of achieving the required fault protection for the circuit.

Kind Regards, John

 

[EFLImpudence]

True.

 

[dhutch]

Why is that?

 

[JohnW2]

Why is that?

Because the Ze in a TT installation is 'inevitably' (virtually always) so high that the fault current resulting from an L-E short will not be high enough to cause an MCB or fuse to operate.

Kind Regards, John

 

[mfarrow]

Ah, I see we've stopped the game of quoting one's own post, for now ...

I don't really see the avoidance of RCD by means of a different method (and not just mechanical protection) as being a problem. If you're doing the install yourself, for the price of an RCD you could buy 3 or 4 lengths of 3m 20mm 'earthed' metal conduit to suit 6 or 8 (at least) switch drops. You would then be assured that your lights were not part of an RCD 'colllective'.

Furthermore, with an earthed cabling system your potential exposure to touch current is reduced below those which an RCD would expose you to.

 

[AndyPRK]

I still think a wylex would suit. This allows 3 Partitions. 2 RCD and 1 for RCBO or MCB.

You could put your lights on RCBO's, important sockets/heating on RCBO, alarms on MCB and the rest of your circuits divided up by the 2 RCD's.


I'm sure we would love to know what all your circuits are so we can give you many options.
And is your supply TT with earth rod ?

 

[JohnW2]

I don't really see the avoidance of RCD by means of a different method (and not just mechanical protection) as being a problem. If you're doing the install yourself, for the price of an RCD you could buy 3 or 4 lengths of 3m 20mm 'earthed' metal conduit to suit 6 or 8 (at least) switch drops. You would then be assured that your lights were not part of an RCD 'colllective'.

I didn't say that it was a problem. I said that (a) it's more hassle to install than an RCD and (b) that many people ('rightly or wrongly') perceive it as desirable to have RCD protection, per se (in relation to what's on the ends of the cables, not the cables themselves).

Furthermore, with an earthed cabling system your potential exposure to touch current is reduced below those which an RCD would expose you to.

If one is planning on hammering nails through cables, yes. However, as above, many people are more concerned about RCD protection for whatever is on the end of the cable.

I'm not knocking your suggested approach as a possibility - merely indicating that it is not an approach that I believe many people would take.

Kind Regards, John

 

[JohnW2]

I still think a wylex would suit. This allows 3 Partitions. 2 RCD and 1 for RCBO or MCB.

You keep saying this - but what exactly what do you mean by 'a Wylex', and why only Wylex? Wylex offer dozens, if not hundreds, of CU sizes/configurations, and almost all other major manufacturers of CUs also offer ones which offer the sort of '3 partition' arrangement you mention above.

Kind Regards, John

 

[AndyPRK]

Sorry to upset you John.

I meant a 15 Way NHRS15SSLHI
As seen here :

http://www.ebay.co.uk/itm/WYLEX-15-...ls_Supplies_Electrical_ET&hash=item19ec353c7e


I'm sure there are other manufactures, just need to ensure it has the 3 neutral bars.

 

[PrenticeBoyofDerry]

I would personally put the smokes on the downstairs lights, not only does it offer the advantages of lights out, smokes out, but also frees a way for you.
I would go with two RCD set up, with selected circuits on RCBOs, I prefer to have the boiler on RCBO or unprotected MCB (regs permitting) and also try to get some lighting on RCBO or again unprotected MCB (regs permitting).
The BG boards are decent for the price and RCBO prices reasonable. I am sure the do a 20 module board.

 

[JohnW2]

Sorry to upset you John.

... and I'm sorry if I gave that impression. I was in no way upset, merely confused by your references to 'a Wylex'!

I meant a 15 Way NHRS15SSLHI

Thats's better I know them well, I have at least a couple of it's 'smaller brothers' (NHRS10SSLHI) in my house!

I'm sure there are other manufactures, just need to ensure it has the 3 neutral bars.

Indeed. The ones with 3 neutral bars (hence 3 'partitions') are often called 'high integrity' (although I've never quiet worked out why!) - I believe that's what the 'HI' at the end of the Wylex part number represents.

Kind Regards, John

 

[STEVEROG]

I'm pretty much decide then, dual rcd it is.

I guess I now need to decide which one of the many consumer units to go with. I'm after something with a fair amount of wiring room that will allow a nice tidy job. I imagine there will be a lot of personal preference but if there's a no-brainer unit that's great quality I'd like to know about it?

SGR