Electricity supply for boilers

[Doctor Drivel]

This man is senile.

[Doctor Drivel]

They are. This man is senile.

[ARW]

Make and model number?

Maybe a couple of photos of the new RCBOs.

[ARW]

Immersion heaters are sold by the inch:-)

[charles]

"Senile" = "showing decay of old age"

Doesn't apply - he's younger than me.

[Doctor Drivel]

Cor blimey Guv! Double senility.

[John Rumm]

Like strapping buttered toast to the back of a cat and dropping it ;-)

[Doctor Drivel]

Amazing what they do in Essex.

[John Rumm]

While it creates no immediate danger, it would be poor design. Ring circuits are well suited to provision of diverse power, but not intended for substantial long term loads. So a dedicated radial for the immersion would be much better.

With that load scenario, pretty unlikely - however the point is a fair one and an illustration of why large long term loads on ring circuits reduces their flexibility.

Damn, I think I just agreed with dribble... he must be slipping.

[John Rumm]

But they are very different types of load.

[Doctor Drivel]

Poor design yes. But it is NOT against the regs.

By not against the law - the regs.

[charles]

if you say the Regs are the law, why isn't BS7671:2008 the law, too?

[Dave Liquorice]

"Rapid Boil" kettles are around 3kW, ordinary kettles are less 1.5 or

2kW. But yes a few minutes is rather different to an hour or more.

The other thing to bear in mind is that the immersion is for emergency use when the boiler has failed. Failed boiler no doubt means no heating either so the electric fires will come out. What's a ring, 6kW? Half of that for the immersion doesn't leave a lot for all the stuff that is normally on plus a couple of 2kW electric fires...

[Doctor Drivel]

Good point.

[Doctor Drivel]

Don't know. Don't know.

[David WE Roberts]

I am looking at fitting (or having fitted) a new combi boiler. The new boiler would be installed into an airing cupboard in the bathroom (with suitable access space), to replace the existing floorstanding Thorn system boiler in the kitchen.

In terms of electrics - if it fine for the boiler to be powered from an existing ring main (fused spur, switch-able outside of the bathroom), or does it need its own fuse direct from the CU? I am just trying to work out how much other work would be involved.

Thanks, Matt

**********************************************************************************

One thing I don't think has been mentioned amongst all the playground scrapping.

Over winter, the central heating is something you want to be available at all times. You may also want to do maintenance or fault finding on electrical circuits. You don't want to have to chose between being warm and working on your ring main if this can be avoided.

Brought home to me when I discovered that my central heating was on a fused spur off the downstairs lighting (but not noted at the CU).

Cheers

Dave R

[Dave Plowman (News)]

Just another reason to follow current regs and have it on its own radial - as said here by those who understand such things.

Once dribble goes back into the clinic all this nonsense will stop again. Dunno why he was ever let out.

[Fred]

I think the statment above is incorrect.

An immersion heater is rated at 3kW.

The current drawn by the heater will be: I=P/V

3000/240=12.5A

So if the OP uses a 6A RCBO this will trip whenever the immersion heater is switched on, meaning he can never get hot water from the immersion heater.

If on the other hand, the immersion heater is disconnected and never used, then yes, a 6A RCBO or MCB would be the right rating. But why would you want to disconnect and never use the immersion heater? In many homes they are only used when the boiler fails, but in those instances, you will be glad that you have one that is wired-up.

If the OP wants to use the immersion heater cable, he should spur off it and fit a 5A fuse in the fused connection unit to the boiler but use a 16A MCB or RCBO in the CU.

If the OP runs a dedicated cable from the CU to the boiler only, then it would be right to use a 6A RCBO or MCB.

(But I am not an electrician, so the usual disclaimers apply)

[Dave Plowman (News)]

The OP is fitting a combi.

[Doctor Drivel]

What the f*ck are you on about?