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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> CU ? https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1092307993 Message started by jaja on Aug 12^th, 2004, 11:53am

Title: CU ?
Post by jaja on Aug 12^th, 2004, 11:53am

Do you get problems with CU with just a 80 amp RCD main incomer , or is it best to go for to go for split load CU, with RCD + main switch!
in case of trippin problems

Title: Re: CU ?
Post by Beanzy on Aug 12^th, 2004, 12:33pm

Depends on supply type. But speccing a Consumer Unit up isn't really a DIY job.

On TT supplies best to have a 100mA RCD main. Split load are good for avoiding whole installation shut-down/ black-out just because the kettle goes dodgy or you splash water on a socket in the kitchen. Best ensure the sockets are protected by a 30mA RCD and any garage or outdoor supplies.

Bit more info on scenario would help. Once we have that then will probably want some more info on loads and characteristics of suppliers installation.

Title: Re: CU ?
Post by rabbit_rabbit on Aug 12^th, 2004, 6:54pm

Giving a generalised answer to a generalised question I would always lean towards a split CU nowadays and rarely think twice about it. 100A main (on a 100A cut out) and a 63A or 80A 30mA RCD. If it's TT (overhead supply - yet more generalising!) then most certainly a 100A 100mA Main RCD).

I suspect the day will come when you will not be able to buy non split CU's and that would be a good thing.

RR

Title: Re: CU ?
Post by The_Trician on Aug 12^th, 2004, 7:28pm

I prefer an enclosure full of RCBOs!

TT

Title: Re: CU ?
Post by Lectrician on Aug 12^th, 2004, 7:47pm

good call TT - not much more expensive if only one or two rings :-)

Title: Re: CU ?
Post by rabbit_rabbit on Aug 12^th, 2004, 8:16pm

lol TT - ya have to be right of course EVERY cct should have its own RCBO. Now let me see, each RCBO at �45, that's 10 cct that'll be �450 plus a new CU box, that'll be another �80, plus fitting ......"Err that will be �800 Mr. Bloggs".

I like it - as the yanks use to say "raise the ASP" (Average Selling Price) and THAT is JUST how ya do it!

Ray

Title: Re: CU ?
Post by plugwash on Aug 12^th, 2004, 10:32pm

if you are using rcbos you only rcd the stuff that needs it (either by regs or in your professional opinion)

i can't imagine you haveing more than 4 or 5 cuircuits that need to be rcd protected

it is a pricy option compared to a split CU though

while there is nothing in the wiring regs preventing a 30ma rcd as main incomer it may bring problems with stuff like fire alarm regs

Title: Re: CU ?
Post by L.Spark on Aug 13^th, 2004, 5:14pm

yea your right plug, Fire alarms and Emergency Lighting have to not be run on the RCD and on it's own dedicated circuit.

Title: Re: CU ?
Post by sparky_si-fi on Aug 13^th, 2004, 11:23pm

i love RCBO's as well

I have ran out of room on the re-wire I am doing at the mo so a small 4 way enclosure,100A isolator 6A CB for lights 32A RCBO for the socks and 16A CB for the immersion/central heating,

'bout 55 quid if memory serves me...