Massive electric bill

[Badfish]

Hi guys

Any body heard of a new digital meter being faulty and causing a customer to have a huge electric bill or is there any way that an electrical installation could cause the bill to be huge apart from leaving things on all the time?

 

[Apache]

Need more info

 

[Sidewinder]

Defo need more descriptive info on the situation!

 

[sellers]

your probably leaving things on, how huge is huge?

A mate of mine complained about having a very high bill, I took a look. His water was heated from a megaflow cylinder with 2 elements. He had programmed the timer to go OFF for 2 hours in the morning and then again for 2 hours at night. Giving him 20hrs of water heating on his bill!! O dear!!! Since then He has realised which way to switch the toggles.

 

[Badfish]

This is an extension and rewire on a largish house with 3 phase supply running a ground source heat pump and using one of the phases for the house board. The 3 phase was brought in with a new meter and the owner has a massive bill for about a

 

[Sidewinder]

Heat pump is not cheap to run if it is not working in optimum configuration.

Imbalanced loads can increase bills.

You need to do a load analysis really as a base line.

 

[sellers]

sounds way off to me.

Allthough you can never tell untill theres 2 meter readings, if its estimated they may say see it as a new 3phase supply with no previous records, therefore 1k to cover their behinds.

 

[NozSpark]

What were their previous bills and what (if any) work has been done before the rise?

Would it be worth hiring a data logger for a week?

 

[kme]

Imbalanced loads can increase bills..

TPN load last Feb - I put in a TPN board, and `roughly` balanced the loading (more works to come).

Customer`s bill dropped from

 

[Badfish]

the old bills were on an old single phase this in now not used and everything is now on the 3 phase. bills have been around a grand quarter for about a year.

As the house DB is run off one phase of the heat pumps 3 phase is this out of balance enough to cause these high bills?

 

[kme]

Yup. The heat pump can be classed as balanced, so you`re out of balance by the domestic supply usage.

A `rough` way to understand three phase metering (technically incorrect, but you`ll get the idea).

Imagine the meter looks at all three incoming phases; reads the largest and records it. The you are billed for 3 X that amount.

For instance:

L1 : 48A

L2 : 16A

L3 : 16A

The meter will record L1, and you are effectively billed for 144A, though you`re only using 80A. As I said, it isn`t quite that simple, but, described in lay terms, it is close enough.

KME

 

[Badfish]

so the best thing to do is try to bring some of the domestic circuits on to the 3 phase board and try to balance it all out then?

 

[Badger]

yes that would be ideal if the domestic board is changed to a 3 phase and domestic circuits shared across the phases equally

 

[Badfish]

Cheers guys, at the moment there is a 3 phase board and a domestic board in the same cupboard.The heat pump is 20A per phase so if i take some circuits of the domestic board and try to balance it all that way i should not have move/remove any boards.

 

[Sidewinder]

Badfish,

You need to be caereful as to where you end up with 400V potential.

e.g. you don't want the upstairs & downstairs lights on differing phases if say the downstairs hall light & the upstairs landing light are in the same switch as the stair lighting giving you a light switch upstairs with 400V in it and the same down, if you get what I mean.

Also say the light and shower in the bathroom on differing phases may not be a ggod idea.

There is some guidance with respect to this but I can't recall the details now, perhaps something like 2m apart and/or labelling?

Would need to check.

 

[Badfish]

Sidewinder ,

Thanks for the advice,i was thinking of moving the socket circuits to the 3ph board maybe that would work?

 

[kme]

Not really; it may help a bit, but you need to spread the load from the domestic DB onto the other TWO phases as well - if you could move the up sockets to one, and the down to another, that could help - it really depends on the current distribution of domestic loads, circuits available, and proximities to one another, as Sidewinder pointed out.

KME

 

[sparkytim]

Not ideal but not prohibited.

Just warning label required BEFORE access to live parts where Voltage > 230

as well as where 400 volts exists between outlets that can be reached simultaneously.

BRB Pg 93 514.10.1

 

[Sidewinder]

Thanks Tim,

As usual no book to hand!

Thing is in a domestic do you want 400V warning notices everywhere!

Perhaps with a bit of thought these could be avoided, which was my suggestion to Badfish.

Say outhuses garages etc on the alternate phases?

Or as KME says floor by floor perhaps?

 

[speedster]

Hi,

In view of the size of the bills. A data logger for a week or two will tell you everything you need to know and is probably a cost effective option.

But before doing anything else, I would scrutinize the bill to see how much of the bill is for units of electricity used and how much is for standing charges etc, and compare theses amounts with previous bills for the single phase metering. Also ,if you have a clamp ammeter,you could check the current from time to time with different equipment switched on and check the loading is as you would expect.

Best of luck ,Speedster.