Electrical supply upgrade

[Doc Hudson]

OK  I think I need speak to the next door neighbour.

In the mean time if I can go back to the original question is there a way to work out the demand?  Maybe a formula where you add up all the appliances and find an average or something.

thanks again for all the help so far.

There is no simple formula, if you try adding up circuits or appliances you would find that 99% of all houses in the country have supplies that are theoretically to small. A lot of other factors need to be taken into account to apply a principle called diversity. The number of people who live or are regularly using power at the property has greater impact then just the number of appliances. e.g. two identical properties with the same number of appliances would have very different power demands if one is a family of 6, running a business from home with people in the house for 90% of the time, compared to a single person who is out away from the house for 60% of the time. You could hire a logger to see what power you are actually consuming at the moment.

Doc H.     

 

[steptoe]

in our house its quite common for the shower to be on [8.5] , the oven on [6 iirc], a load of other non massive stuff to be on,

me welding @3kW, and the compressor to kick in [2.5kW plus start up] at the same time, on a C50 MCB without issue.

too many people tend to think a 60amp fuse blows at 60amps.......

 

[Lurch]

My entire house has one ring main on a B32, and the lights on a B6, not that it really matters though because the entire thing has a 30A BS88 in the cutout. Not blown anything yet.

 

[phil d]

A while ago I posted the values the dno uses to work out its loadings on it's circuits, off the top of my head for a house with gas central heating it's something like 3 or 4 Kw per house. Thats what they use to calculate their loads for feeding say a housing estate, it obviously works because if it didn't you'd get substation fuses blowing all the time, as someone else said, it's surprising how little current a house actually pulls. I was looking for a fault once and I had everything on, electric shower, electric cooker, water heater and loads of stuff on the sockets and I was still pushed to pull over about 40 Amps, Diversity plays a big part in calculations and loading, plus a fuse doesn't blow instantly and it takes a while to blow.

 

[apprentice87]

in our house its quite common for the shower to be on [8.5] , the oven on [6 iirc], a load of other non massive stuff to be on,

me welding @3kW, and the compressor to kick in [2.5kW plus start up] at the same time, on a C50 MCB without issue.

too many people tend to think a 60amp fuse blows at 60amps.......

I clamped a single phase welder i had here once.. It came out at 107A !! Used it for about 20 years on a 60A fuse no problems at all!!

john..

 

[Evans Electric]

All that is very true , HRC fuses especially , will carry high currents for ever. 

I was asking after an obsolete MCB on here , ( forget the make now , )  for a 9.5KW shower .  We installed an RCD and run it up on an existing 30A  MCB ,  couldn't get hold of anything larger . I was looking for a 40A  . 

As Sidey said at the time , with the time / current characteristics ...given the time a shower takes it will have to do.   And about 2 years later I've had no call back .  

So thats a  a 9.5KW shower  @ 41A   running on a 32A MCB with no problem .

 

[Doc Hudson]

Another quick observation, if this granny annex is going to be used by a 'granny' (or granddad), then they probably wont be consuming much power anyway. Whereas if the annex is more of a man-cave, it may be a different story.

Doc H.