Electrics Question

pianistdave

This may be a really obvious question but whilst I'm getting my head around plumbing since starting DIY in earnest last year, I've only recently started needing to think about electrics!

My understanding is that a ring main is made up of 30 amp cable, with each outlet providing a maximum of 13 amps. If, say, a kettle uses 10amps and I were (for some strange reason) to plug in and power four kettles at once, would this cause the fuse box to trip?

I'm asking because it would seem that my upstairs and downstairs rooms (two reception, two bedroom) are on one ring main and so it would seem that the above scenario (but with something more interesting than a kettle) could easily happen if there were several appliances being run. (The kitchen is on a separate ring so at least kettles won't cause the issues I'm enquiring about!).

Thanks in advance
Dave

zagfles

pianistdave wrote: »

This may be a really obvious question but whilst I'm getting my head around plumbing since starting DIY in earnest last year, I've only recently started needing to think about electrics!

My understanding is that a ring main is made up of 30 amp cable, with each outlet providing a maximum of 13 amps. If, say, a kettle uses 10amps and I were (for some strange reason) to plug in and power four kettles at once, would this cause the fuse box to trip?

Probably not immediately - you can go a bit over the fuse rating for a short time.

I'm asking because it would seem that my upstairs and downstairs rooms (two reception, two bedroom) are on one ring main and so it would seem that the above scenario (but with something more interesting than a kettle) could easily happen if there were several appliances being run. (The kitchen is on a separate ring so at least kettles won't cause the issues I'm enquiring about!).

Thanks in advance
Dave

This seems pretty normal - why do you think you'd ever use over 30 amps for non kitchen sockets? Several electric fan heaters perhaps?

It's usually more likely you blow the kitchen ring main fuse as most high power devices are in the kichen eg kettle, toaster, microwave, oven, dishwasher, washing machine etc could easily add up to over 30 amps. But even there unlikely they'd all be drawing max power at the same time for long enough to blow the fuse.

pianistdave

Thanks - I was under the impression most houses had separate ring mains for upstairs and downstairs but perhaps I'm wrong.

Ectophile

It's common these days to install one ring upstairs, one downstairs, and perhaps another for the kitchen or utility room where the high-power appliances get plugged in.

But back in the olden days, it was one ring for the entire house.

If the wiring has been modified over the years, then assume nothing (my kitchen is on two different rings).

Mr.Generous

some do, some don't. Some split front of house and rear. Cookers are often on own circuit. Fan heaters typically 2000w so you'd need a good few of them on. Older mains boards have a total capacity of 60amps - more modern are 100amps. With the 60amp boards you can imagine a scenario where an electric shower and hob on together exceed the total rating, but not a ring main. If the oven was 2200w and on the ring - call it 9amp you'd still have 21amps (fuse board) or 23 amps (breaker board) to play with. 20amps is 4800w - what are you planning to plug in? maybe an air con unit, and a hairdryer all together could do it, all the usual stuff on too like fridge/freezer/tv/computer/router/lamps/

thescouselander

pianistdave wrote: »

Thanks - I was under the impression most houses had separate ring mains for upstairs and downstairs but perhaps I'm wrong.

I always thought this too until I found out our current house has a separate ring for each side of the house. According to the last sparky we had round here it's a quite common arrangement.