Me and the flat next door are on the same electricity supply. My consumption is the main meter minus their submeter. I've been playing with a couple of remote electricity meters (the OWL CM119). Are there any meters that would let me monitor both subsupplies at the same time and do the relevant subtraction for me?
JGH
Are you just trying to keep an eye on your own power consumption here?
These meters that clamp round the cable are not very accurate, especially if you have CFL "energy saving" bulbs
What are you trying to achieve here?
Avoidance of mental arithmetic.
JGH
Whatever happens you need to read the meters and take one from the other for billing purposes, as the clamp on meters are not accurate enough, nor certified calibrated.
If you just want to see your own consumption on the wireless device, then clamp the thing around the main cable into your consumer unit (fuse box)
Toby...
But that measures my consumption *and* *my* *neighbour's* as her submeter is a spur off my consumer unit.
I read the measurement from my consumer unit (me+her) then subtract the measurement for hers (me+her-her=me).
JGH
I see, Whenever I have seen sub metering, the tails of the meter have been split and a switch-fuse installed for the sub main, before the "main" consumer unit, mainly so you can turn everything off in one consumer unit without taking the other property off supply I assume.
I think the owl unit you have is Ok for three phase, so I wonder if you got another clamp, reversed the polarity on the plug that connects to the transmitter, and plugged it in, it would cancel hers out?
You could test the theory by making up a reversing adaptor (so you don't have to cut the plug off) with a few bits from Maplin or wherever - See if you can get the thing to show a negative reading - if it does, then it will probably work
...actually, just send Owl an email, I have had communication with them before, and they are helpful.
I don't want to teach anybody to suck eggs, but the way you've used the term here suggests some confusion over what a consumer unit is. It is not the meter with dials that you read, it is the box with fuses or circuit breakers ("trips") for each circuit in your flat.
Apologies if this is obvious.
Pete
Is there a separate switch or fuse ion your consumer unit, alongside your trips for things like your sockets and lights?
If you can take a picture of the thing the neighbors electricity meter is connected to, this might clear things up, if you are unsure!
Toby...
So you need to clamp the sensor to the submain between your consumer unit and hers. If it's not wired in tails you'll need to split the T&E or SWA to gain access to an individual wire, whilst maintaining insulation and sheathing over a single core, possibly by mounting the cable and sensor in a suitable enclosure.
However if this is for metering (charging for) a tenants supply then there is a legal requirement (it was mentioned here a while back but I can't find it) for the submeter to be approved for the resale of electricity, and the 'energy monitor' type will certainly not be.
As presumably they're your flats, why don't you get proper separate metering installed?
Owain
It seems like a adhoc/add on set up to me. A separate company metered feed(*1) would incur another standing charge(*2) and no doubt a connection fee of some sort.
Personally is it really that hard to read the two meters and subtract one figure from the other?
(*1) Others have mentioned the legal requirements for the metering of resold electricity.
(*2) Even the "no standing charge" tariffs effectively still have the standing charge via the first X units costing more. To my knowledge Equipower is the only true no standing charge tariff.
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