Combi-Boiler

[willowwaters]

Can anyone tell me if its ok for a Combi-boiler to be spured off a ring main to supply it or does it require its own circuit?

thanks

 

[Darkwood]

Its best to have the boiler on its own circuit as if the installation is 17th regs then a ring main fault would lose your heating too so recommend depending on cable routing it has seperate rcbo and isnt then prone to nuisense tripping because of fault on other circuit.
Think about you gran in the middle of winter, if she lost power to a socket circuit you wouldn't want her to lose the heating as well.

 

[willowwaters]

Cheers for that mate.

Could you tell me what size RCD it should it be on?

Im I right with these RCD ratings

Ive also got 2 x ring mains both supplying about 8 double sockets each on 2 x 32 amp breakers
1 x cooker circuit on a 40 amp breaker
2 x lighting circuits on 10amp and 6amp breakers

Got a guy coming to part P test it.

Would appreciate your input

 

[Darkwood]

These are mcb ratings and although they sound ok i dont know cable size for cooker and installation methods so cant comment on the 40amp, rcd rating should be 30ma covering each of these circuits as a front end device or combination device 'rcbo'.

 

[willowwaters]

Ive installed 2.5 T+E for the rings , 6mm T+E for the cooker , 1.5mm T+E for the lighting

If that helps

 

[Darkwood]

What you tell me is what i expect you used but there is alot more to it than that, without trying to worry you it comes down to routing of cables, length of run etc etc generally lighting and sockets can be wired by rule of thumb but cookers and showers need a little more than rule of thumb and routing and length is a big factor when picking mcb rating and cable size.

 

[willowwaters]

Yes I'm aware of that but its only a bungalow and the cooker is about 7 meters from the dis-board across the loft and capped down the wall before the plasterboard was put on.

There are no electric showers they come from the boiler

 

[Darkwood]

as long as its clipped out of the way of insulation and dosni't pass through it, taking into account future insulation of loft then it should be ok

 

[super_stuey]

wot about the power comsumption of the cooker?

edit: unless of course there isnt one there yet! forgot about that.

 

[ezzzekiel]

Got a guy coming to part P test it.

Would appreciate your input

unless he installed it then he shouldn be doing anything to it

 

[Bobby B]

I'd spur it off the ring quitre happily, it's own circuir would be nice but is it practical? unless you go mad and put it on an rcbo on it's own it might aswell be on the socket circuit as it would be sharing an RCD with one of the ring mains anyway and chances are if ring trips the RCD will to so, your no better off really. uness of sourse you can do it without chasing in and put it on a MCB on its own that'd be ideal

 

[Darkwood]

This is the whole point of feeding combi on own circuit you dont want inconvenience and in the middle of winter losing your heating due to an unrelated fault can be a big worry for the elderly and young and must be considered irespective of who lives in house at present, if heating had own rcd (if needed due to installation methods) then if it tripped then obviously the fault is on the heating circuit anyway and unavoidable to loose heating.

 

[willowwaters]

So there are no rules saying it has to be on its own circuit then?

I can re-wire another wire to it and put it on its own mcb but if i dont have to I wont.

Cheers

Ok I'm getting what your saying , I am going to live in the property and have 2 young children so I'll pop another cable in and put it on its own circuit....what size??

 

[Darkwood]

So there are no rules saying it has to be on its own circuit then?

I can re-wire another wire to it and put it on its own mcb but if i dont have to I wont.

Cheers

It is part of the regs the the design of the installation must be so as to avoid nuisense tripping and in convenience, it is also good working practice to put alarms, boiler and smoke alarms (if seperate from lighting) on their own circuit protected according to their installation methods.
So its your call many dont bother but i personally work by good practice methods.

 

[super_stuey]

thats right mate, I agree with darkwood about the inconvenience, own circuit would be better but there is no reg saying u have to.

installation methods and power rating will determine cable and fuse.