All a ring main gives you is the chance to use thinner cable since you're essentially wiring each outlet with two cables - one from each side. We do per-room stuff, just don't happen to run the end back to the service panel (so it uses less wire in the end, though the wire may be thicker). 240V is better from copper utilization point of view, but 120V will rarely shock you to death. Though I did have fun once when I cut through a 14/3 wire (14 gauge, two hot on opposite "legs" and 1 neutral) - this is 240V hot-to-hot situation and the explosion I got when the wire cutters went through nearly caused me to have to do some laundry. My hands were blackened, too, by the vapourised insulation! One nifty trick for ex-pats, though, is that outlets in kitchens are wired as "split recepticles" - this means you get two outlets that share neutral but use opposite 'hot' legs - so you can easily wire up two plugs to give you a 240V circuit. Handy for kettles and other European appliances. Of course, always check that the outlet is really wired that way before proceeding :)

I think we have higher capacity service entries here too - my main house has 200A @240V and the new house has a 400A entry - giving 96kW if we need to run an arc furnace or somesuch ;)

Paul in Montreal.

So, P-i-M has his pair of plugs, wired up to a kettle, pushed into two adjacent sockets. He pulls one out and wonders what happens if he touches the “hot” pin.

Rather reminds me of a friend at school who decided he wanted 480 V so wired two plugs in series and pushed them into two adjacent sockets. His father was less than entirely pleased.

Posted By: Ed DaviesSo, P-i-M has his pair of plugs, wired up to a kettle, pushed into two adjacent sockets. He pulls one out and wonders what happens if he touches the “hot” pin.

Actually no, I don't even have a kettle. Was deported from the UK for not drinking tea.

When I was with the ex-wife, I just wired a UK extension bar into the back of the stove where a red and black wire were conveniently there to give 240V. Just didn't cook and run the appliances at the same time :)

Paul in Montreal.

Posted By: Paul in MontrealAll a ring main gives you is the chance to use thinner cable since you're essentially wiring each outlet with two cables - one from each side. We do per-room stuff, just don't happen to run the end back to the service panel (so it uses less wire in the end, though the wire may be thicker). 240V is better from copper utilization point of view, but 120V will rarely shock you to death. Though I did have fun once when I cut through a 14/3 wire (14 gauge, two hot on opposite "legs" and 1 neutral) - this is 240V hot-to-hot situation and the explosion I got when the wire cutters went through nearly caused me to have to do some laundry. My hands were blackened, too, by the vapourised insulation! One nifty trick for ex-pats, though, is that outlets in kitchens are wired as "split recepticles" - this means you get two outlets that share neutral but use opposite 'hot' legs - so you can easily wire up two plugs to give you a 240V circuit. Handy for kettles and other European appliances. Of course, always check that the outlet is really wired that way before proceeding :)

I think we have higher capacity service entries here too - my main house has 200A @240V and the new house has a 400A entry - giving 96kW if we need to run an arc furnace or somesuch ;)

Paul in Montreal.

bloody hell, your grid must be well over supplied if they think a domestic customer could draw that sort of load.

a few years ago a BCO suggested i change the 60amp main fuse to a 100, i said its only a small 2 bed terrace and would be almost impossble to draw in excess of 60 amps (bar plugging a kettle in every socket), i never changed it

Posted By: nikhowardbloody hell, your grid must be well over supplied if they think a domestic customer could draw that sort of load.

Don't forget that 70% of people in Quebec heat using straight resistance heating. It was as easy to a 400A entry as a 200A, though they utility did have to put in a new transformer :) No way we'll ever need 400A though.

Paul in Montreal.

Probably 60A

I have a 100A main fuse, so that will be 100A x 230V = 23 kW
Say I put the washing machine on at night during the winter, that draws 8A when heating the water, the two storage heaters draw 20A, water heating is another 12A, pop the kettle on and that is yet another 12A, so I could easily draw 52A under normal conditions. That will be 12 kW.

Posted By: SteamyTeaProbably 60A

I have a 100A main fuse, so that will be 100A x 230V = 23 kW
Say I put the washing machine on at night during the winter, that draws 8A when heating the water, the two storage heaters draw 20A, water heating is another 12A, pop the kettle on and that is yet another 12A, so I could easily draw 52A under normal conditions. That will be 12 kW.

I'm sure it's not unusual for an electrician to find a house with a 10kW electric shower and the owner wanting another in the new ensuite.

200 A at 240 V might not leave a lot of margin if you're already running lots of stuff then a big heat pump starts with six times inrush current.

How about 25 A? Basic monthly charge is based on capacity as well as use so I'm happy. My load averages around 5 kWh per day but then I've relocated, down-sized and kill-switched. Isn't that what GB is all about? Reading on here about houses of 300 sq.m tells me that some are not getting the real threat to the future of our grandchildren.

Edit: Ooops!

And to stay on topic, standard european boxes are interlocking, 70 x 70, in plastic. Cable offered up in plastic corrugated flexible conduit. I cut holes after dry-lining and anchor with paste.

I do like the EDF 'breaker charge' retail scheme to cap peak load. A good and simple piece of the puzzle.

Rgds

Damon

Posted By: Ed Davies200 A at 240 V might not leave a lot of margin if you're already running lots of stuff then a big heat pump starts with six times inrush current.

The auxiliary heater on one heat pump is 10kw and the other one (in the 400A house) is 15kw ... so it's quite easy to get way over 100A if there a few other high consuming devices are on at the same time. For me, this usually doesn't happen as we have gas cookers, but you have to have some margin in the supply. For people who heat with straight resistance, it's quite easy to get to over 15kW in the depths of winter. 100A entries used to be the norm but I don't think anyone puts in less than 200A now.

For my heat pump the LRA ("locked rotor amps" or starting current) is about 90A - it's on a 40A breaker which doesn't seem to mind this. Running current is about 12-16A.

Paul in Montreal.

[edit various spelling corrections etc.]

Posted By: Ed Davies

Posted By: DamonHDI do like the EDF 'breaker charge' retail scheme to cap peak load. A good and simple piece of the puzzle.

Does it make much difference, though? Unless the cap is very low (e.g., the 5 kW for domestic on Eigg) so few households will be close to their limits that it won't make much difference to the national load. E.g., in the UK if everybody took an extra kW at the same time (i.e., an extra 60 GW total) we'd run out of electricity very quickly - yet most households won't be within a few kW of their limit most of the time.

I imagine it does help: put on a 3kW kettle and any other white goods with heating or an immersion and you'd be at your limit at 5kW; switching on the toaster (another 1kW or 2kW) and 'pooooof' you'd be learning the value of peak load.

The EDF scheme last time I looked at it came with a number of tiers and may have been combinable with their red/white/blue variable-kWh-pricing scheme too.

It would definitely help constrain DNO costs/planning as well, as you suggest.

Rgds

Damon

Posted By: CWattersHow about changing the way TV programs are broadcast so that advert breakes occur at slightly different times in different parts of the country... or even mandate it so they are at different times on different channels.

This is becoming moot as more and more people watch TV via a PVR that time-shifts the programs and allows the ads to be skipped anyway.

Paul in Montreal.

Posted By: Paul in Montreal

Posted By: nikhowardbloody hell, your grid must be well over supplied if they think a domestic customer could draw that sort of load.

Don't forget that 70% of people in Quebec heat using straight resistance heating. It was as easy to a 400A entry as a 200A, though they utility did have to put in a new transformer :) No way we'll ever need 400A though.

Paul in Montreal.

but surely in the super insulated timber framed houses you have told us about, the electric heating never has to work too hard even when it is -20C outside!

Posted By: TimSmallGetting off-topic, but... A 13A plug-top fuse will pass 20A for about an hour before blowing. This can sometimes be a bit problematic with cheapy rubbishy plugs (i.e. most these days) - see link at top of:

http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=46930&enterthread=y" >http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=46930&enterthread=y

Not just the plug fuses that are like this. Last winter at work we were running 87 amps through the 60 amp 3 phase fuses before they went.

Back on topic, I am about to do first fix electric in a timber frame, with a 2x2 service cavity (e.g. 45mm deep). A drylinner and taper (also self built a few houses) told me to use metal back boxes and not the drylinning ones. As the back of the cavity is my VCL of polythene, should I try and protect this a little (e.g. hardboard I have a lot of spare panelline lining around) from the metal back box?