economy 7 credit meter reading?

[fog]

Hi
Have divided premises into 2. Upstairs offices, and downstairs shop.
The heating is via economy 7 storage heaters.
Have installed 4 DB's
1)down 24 hour
2)down economy 7
3)up 24 hour
4)up economy 7
Also installed 2 x L & G credit meters so owner can calculate/bill the down stairs which is being rented out.
credit meter 1 is for the 24 hour electric.
credit meter 2 is for the economy 7 electric.
Question Can I power the economy 7 credit meter so it shows what is used, so customer can calculate the total electric bill for rented part of the premises, from the 24 hour DB. and how please?

 

[LVSparks]

If you have 4 DBs then fit a meter to each DB.
Fit the old disc meter with the numbers which can be read regardless if there is power or not.

 

[UKMeterman]

The question is when are the supplies actualy live?

For what you have suggested above you will need two standard credit meters for the E7 boards, assuming that they will only be live during the E7 period. For the two 24 hour supplies you will need dual rate meters ( the electricity is cheaper in the E7 period), look for ones that could be used with an external time clock, use the E7 feed in some form to control when the meter switches between the two tariffs.

 

[YoungScud]

It probably won't be possible to use the DNO's timeswitch or teleswitch to switch your own two rate meter since that would involve breaking seals. I've attached a diagram of how a typical E7 tariff would be installed. The L Load tail is split through a block, one tail out feeding the Domestic board and the other through the timeswitch or teleswitch feeding the storage heaters. The smaller brown and blue wires simply feed the switch and the small black wire becomes a neutral when the timer switches over, completing the rate changeover relay circuit in the meter. You could, I suppose, break single rate meters into each of the CU feeds, but the one for the Domestic board wouldn't give you the breakdown of normal and low rate units. If you wanted to fit a two rate meter into that circuit, you'd need a separate timing device with times matched to those of the DNO meter, and that would be difficult. If you decide to go down that route, one thing to remember is that you won't need to change the times twice a year since the DNO doesn't. Usually times are set to GMT, so the heaters and the normal/low rate relay run an hour slow during BST. I hope this gives you some ideas.

 

[UKMeterman]

Hang on,
The off peak supply becomes live when there is the E7 period, this could be used to drive the coil of a relay that could then control the rate switching of the secondary meter. It would be usefull if the secondary E7 load was also driven via a contractor controlled by the same relay so a fault would become obvious very quickly. This arrangement could also save one set of tails as then both the scondardy 24 Hr supply and E7 would go to the same meter and E7 load brought in via a contactor at the same time as the rate changes on the secondary meter.

 

[YoungScud]

See? Necessity is the mother of invention. We've gone from four single rate meters to two two rate meters with the click of a keyboard. Good thinking UK. With brains like that, I'm guessing you're in the metering game (well, that and your name).

 

[UKMeterman]

See? Necessity is the mother of invention. We've gone from four single rate meters to two two rate meters with the click of a keyboard. Good thinking UK. With brains like that, I'm guessing you're in the metering game (well, that and your name).

If the landlord is still resident then you only need one new meter, and be able to subtract one from the other. Note the installed 2 rate meter does need to pass current for all the connected load. E7 and 24Hr. The relay is there to make tampering more awkward.

I do not work in the metering industry, I do have an MSc on how to detect and carry out meter fraud though.

 

[YoungScud]

My won background was primarily in metering for a DNO, latterly 8 years as a trainer, recently retired.