I check mine by arranging my spreadsheet to show both what I am paying on E7, and how it differs from the standard charges. With a low rate use of around 35%, I am saving about £70 per year.
Chris
Or the time switch with a feed to the meter to tell it which register to increment.
They are normally on individual spurs from a seperate CU that is fed via the timeswitch/meter that only powers it up during the off peak period. A ring (7 kW ish) wouldn't have the capacity. 2 large and one small heater here pull 8 kW, there is another large one that is currently bust. If they were all on the load would be around 11 kW for the best part 7 hours... and yes the 16 mm tails do get warm.
This also leads to another question what is the allowable off load/on load supply voltage drop at the meter. When the 8 kW of E7 clonks in here the volts drop by about 10. Still only down to 235 ish tso well inside the 216 to 255 range but I'd expect the load regulation to be better than that allowed by the spec. Dropping from 255 to 216 on say a 10 kW load increase would imply 1.7 kW being dissipated somewhere other than the load...
When I last had them the leccy man set the clock from 22:00-midnight and
02:00-07:00 Very useful for reducing your late night "top up" from a conventional heatertim
now that they are "radio" controlled, I think that they are.
not that you'll be using the heaters in the summer :-)
tim
If they are radio controlled not all are by any means. Our E7 time switch is mains driven with a broken (or non-existant) clockwork back up. We had "off peak" from 1045 - 1800 until the end of March when a series of power cuts moved it to 2045 - 0400.
Balancing & Settlement Code 7647 says that the teleswitches should treat the transmitted time as UTC but in practice not all do and a code for doing +/- 30 min steps in localtime offset from UTC is in the time messages.
Is fascinating.
The lions share probably being outside of your house in the supply wiring with any luck (assuming your wiring is of adequate size and meets the voltage drop requirements)
The wiring pre-meter is not mine or are you refering to the loaded wiring that is? In my case of a 10 V drop when the 8 kW of NSH kicks in is that measured on a ring where the load isn't changing so this 10 V drop is in the tails/supply somewhere. TBH I'm not that fussed as it's only a small drop, normaly supply variations are similar.
However in the hypothetical 39 V drop for a 10 kW (46 A) load increase case that is, in theory, within the spec of 60 A (13.8 kW) supply. Best part of 2 kW being "lost" somewhere doesn't strike me as being particulary good. Partly from the potential fire risk and partly what does it say about the supply impedance and the abilty of it to give suffcient fault currents to blow fuses within the specified times? Hence wondering if there was also an at meter permissable voltage change for a given power change.
I wonder if anyone's ever built a small transmitter to change their meter to off-peak for more of the time?
It would seem a rather safe way of hacking an electricity supply.
Owain
The bulk of the drop will likely be due to the external supply impedance. So its power being dissipated before your meter, and mostly outside of the house. (you will also get some loss in the internal cables to the heaters, but since that it heat lost to the house anyway, is less of an issue)
If you are seeing 10V drop on 8kW of load (not an uncommon amount IME), that is probably a nominal 8kW at 240V. So call it a notional 33A. That would suggest your supply impedance is in the order of about 0.3 ohms. So a loss of 60^2 X 0.3 = ~1kW. A kW spread over however many meters of cable between you and the transformer is probably not even that noticeable - a few watts per metre perhaps.
As for PFC, the above suggest you have north of 700A available. On a BS1361 incomer, that could open it in 0.2 secs, and 0.1 sec for a BS 88 style fuse.
Probably no more than 20 m from CUs to transformer.
The 16 mm tails and concentric feed through the wall do get warm. You came up with about 1 kW loss in the supply from transformer if that's 20 m that gives 50 W/m yeah that seems about right for how warm the tails get. B-)
I'm not that bothered about my supply but the hypothetical one that drops the full allowable range (39 V) on the application of a 10 kW load. It strikes me that that situation is pushing the spec and may have other implications. It seems a bit odd to not have something in the supply spec relating to power levels, though I guess if there is a maximum allowable supply impedance dependant on the size of supply (40 / 60 / 80 / 100 A etc) that takes care of it.
so 50w/m then...
(although that level of supply impedance seems rather too high at that length)
Note to self - read the whole post first ;-)
Yup...
Wouldn't be surprised it's an ancient small pole transformer. We have a fuse carrier marked 100A. There are now three supplies off that transformer and single incomer. The orginal meter (that has been around the clock) is a 40 A one, another 80 A one was probably added 30 years ago and a 100 A one for the supply that has the storeage heaters on it maybe 20 years ago.
So I would be at all surprised to find the transformer and incomer to be a bit underated... Not that we get any where near 23 kW we might very occasionaly for a few minutes get to 13 kW but then the 10 kW electric shower is still in it's box...
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