Electricity questions (longish)

[Chris Hogg]

I volunteer at my local history Archive. We occupy school-rooms attached to a local Methodist chapel. Roughly every four months the chapel people give us a bill for the electricity we've used in the Archive. Needless to say, the bills recently have been going through the roof. Unfortunately, churches etc. don't qualify for the cap on energy prices recently imposed by OFGEM for domestic users, which doesn't help! As we're a voluntary organisation relying purely on donations to keep us going, we've been trying to cut back, otherwise it may break us.

I got involved because I couldn't understand how we were apparently using so much electricity, and thought something must be wrong somewhere. Very few of the Archive volunteers have any technical knowledge, nor it seems do the people from the chapel. "In the land of the blind, the one-eyed man is king". I am that one-eyed man!

I have established that the chapel has a 3-phase supply. There are two meters on the distribution board. One is an Ampy polyphase meter,

very similar to an Ampy 5219, which I think is the primary meter, the second is an old-fashioned spinning disc type which I'm lead to believe records just the electricity used by the Archive. There is also a little unit that I think is a timer of some sort . There are three consumer units DB2, DB3 and DB4, , and respectively. As you can see, there are MCB's for a lot of night store heaters, five in the chapel, DB3, and nine in the school-room, DB4, but in fact the total number between the chapel and the school-room is only about eight, so I presume most of the MCB's are not connected, especially those in the schoolroom. A general view of the distribution board is here Two of the three CU's are off-screen at the bottom. The whole thing appears to have been installed in 2009 or earlier, judging by the label in the lid of DB2.

Is that primary meter a 'smart' meter? The chapel people send a reading to the supplier, SSE, at regular intervals, but only a single reading which includes both chapel and school-room kWh. I'm not even sure which meter they read! Apparently SSE rarely, if ever, send someone to read the meter(s), but rely on the chapel to send in the figures.

At the Archive we always thought that the night store heaters were on cheap overnight electricity, Economy 7, but I'm beginning to doubt that, because there's never a mention of cheap rate electricity on the bills the chapel gives us, and it doesn't sound as though it's on the bills the chapel gets from its supplier.

Question: is it possible to have E7 on a 3-phase system?

What I think is the primary meter has the word 'tot' adjacent to the number displayed, which I assume stands for 'total'. When I was on E7 in a previous home, it was possible to cycle the meter display through day, night and total use. The chapel meter has a little blue button to the right of the display. I'm fairly sure the chapel people don't use that button or even know what it does. Does it cycle the display through day, night and total use, like my previous domestic meter, or does it cycle through the three phases, showing the use on each?

What would the little ESI timer unit be for? If I didn't have doubts about the E7 thing, I'd have said it was to change the main meter from recording daytime over to cheap rate units, but might it be for something else? If there is no E7, what would be the point of it?

Is it possible that the main meter just clocks up usage at a different rate between night and day, times as determined by the timer module, and at a rate proportional to the changing cost of cheap rate electricity versus full rate, so that the indicated kWh actually accounts for the two rates together, IYSWIM. IMO it would have to receive instructions from SSE to be able to do that at different rates depending on how the cost of cheap rate electricity varied relative to full rate, i.e. a *very* smart meter indeed. Were smart meters around in 2009, when this lot was probably installed?

Questions, questions! Any help that you can give me in trying to understand what is going on, will be gratefully received!

[Mike Humphrey]

You've not mentioned DB1, which seems to have most of the installation connected to it.

The meter at the top is on the incoming supply, so that's the supplier's meter. The other one doesn't look very "official" and I'd be pretty sure it's an internal sub-meter. I can't see what's it's connected to, but the cables are heading downwards so possibly DB2, 3 and 4 - DB1 is clearly connected to the henley blocks from the main meter.

The main meter isn't a smart meter. It's not possible to tell if it's a multi-rate meter by looking at it. If you press the "cycle display" button, it will cycle through the different rate readings (if it has them). If it's not a multi-rate meter, you can't be on Economy 7. If it is, it still may or may not be E7 - it's quite possible to be on a single- rate tariff just running off the total reading even if the meter has dual rates set up. It's certainly possible to have E7 on a 3-phase supply. And having storage heaters on a single-rate tariff is almost certainly a bad idea and going to be very expensive.

Mike

[Chris Hogg]

On Wed, 20 Jul 2022 18:07:01 -0000 (UTC), Mike Humphrey [e-mail]> wrote: <long original query snipped)

DB1? I've missed that. Where is DB1 - I don't see it. Are you meaning that little box just to the left of the secondary meter?

I just noticed that the incoming leads at the top have red, yellow and blue tape on them, respectively, and the school-room CU's have these same colours indicated on them: DB3 is on Blue, as is part of DB4, while the other half of DB4 is on Yellow. DB2 is on Red. Thus the consumption is distributed across the three phases, which makes sense.

Still can't see it, see above.

Thanks for those comments. It clarifies the point about E7 at least.

[Colin Bignell]

On 20/07/2022 18:26, Chris Hogg wrote: ...

...

I don't think it is called E7, but you can get a 3 phase tariff with a night rate. My factories had large (about 6ft x 3ft x 3ft) storage heaters and were on one. Eventually the storage heaters, which I think were designed as central warm air heaters for flats, all broke down and I fitted air conditioning instead.

[Andy Burns]

the big metal proteus board at the right, connected to the henleys via the MCG isolator

[Chris Hogg]

Ah yes. I see it now! Thanks.

[Andy Burns]

scribbled near to it (looks like a replacement for an earlier timer?) it say NSH timer, nighttime storage heater timer, all the yellow and blue circuits in DB4 also say NSH, clearly that little timer can't directly switch them all, maybe it controls them via a contactor?

what does the "no touching" notice in DB1 say?

[ARW]

Probably not enough photos - however there is an out of focus image of one of these

which could be operated by a timer to give E7 control if it is a E7 setup

[Chris Hogg]

Ah, so that's what that is. Taken with Andy's comment about the NSH timer, it could well control the E7 switching, if there is any. I wonder if it includes the school-room or just the 'chappl' as it says! Food for thought.

Looking closely at that ESI timer, it looks as though there's a 2.5mm cable coming from it, and there's what looks like a 2.5mm cable entering the Proteus switching unit, the inference being that the timer controls the switch. Progress!

Thanks.

[Chris Hogg]

See my reply to ARW.

I'll have a look next time I can get access to it (it's in the chapel to which to Archive people don't have regular access).

[Andy Burns]

Unless there are two more (not necessarily identical) contactors, the timer isn't going to be controlling storage heaters on all three phases.

[Martin Brown]

The other thing to watch out for it that if your average use of the three phases isn't reasonably balanced you could be paying a premium for that imbalance as well. Ours the heating is split on a floor by floor level so that upstairs is one phase and downstairs the other.

In my own village it simply isn't possible to be on three phase since the local supply has only two live phases at 240vac. Rural villages round here are quite often are tapped off a pair of the three HT lines.

Farmers have been quoted usurious prices to obtain 3 phase supplies from the grid - so much so that many now have their own 3-phase generators!

[Jack Harry Teesdale]

As the technical details have been explained by others, I will just comment on the consumption and billing issues.

Non capped tariffs have generally increased by at least 300% over the past 18 months. e.g if you were paying 10-15p/kWh 18 months ago you could now be paying 30-45p/kWh just for the same consumption, in addition there is the daily standing charge which has at least doubled in most cases.

Trying to make savings on the scenario you have mentioned, with a metering set-up as you describe, is not going to be straightforward AISTM that you have little control over your consumption short of drastic means e.g switching off the NSH's (which the chapel may not approve of anyway).

The fact that your consumption is separately metered suggests that you have little scope for contesting the charges from the church unless you can talk to the person in the church who is responsible for calculating your 'bills' to get a better understanding of how the charges are arrived at.

Whilst i sympathise with your Archive group predicament, i fear that you and they may become a casualty of spiralling cost of energy we are all experiencing.

[Chris Hogg]

The timer itself is only rated to switch six amps maximum. But the Proteus unit is rated to switch 100A, which should be enough to switch quite a few night-store heaters.

It does look as though the 'ordinary' electrics are on the 'red' phase, and the 'blue' and 'yellow' phases supply the N/S heaters, the 'yellow' supplying only the school-room, and the 'blue' phase split between the school-room and the chapel.

My thinking at the moment is that there is no E7 or equivalent: the chap from the chapel who looks after things from their POV didn't seem to know anything about an E7 or cheap rate equivalent. The timer/Proteus switch is simply there to limit the time the N/S heaters are running, in case someone forgets to turn them off. Quite what it switches, I'm not sure. There appear to be only two ?25mm cables going to it, so it looks like it's only switching one circuit, but the cat's cradle of wires makes it impossible to follow them in the picture. I would need to get 'up close and personal' to the distribution board to find out, and I don't think that's going to happen any time soon.

As for Martin's point about keeping the phases reasonably in balance, I don't see how they could be if two of the phases only carry the N/S power and only get used when the timer dictates.

There is still a lot that I don't understand. For example, that secondary meter, the one with the old-style rotating disk, is a three-phase job (the paper sticker behind the glass says so), and judging by the number of cables going into it's base, it's connected to all three of them. So it presumably records the total power going to the school-room, night-stores and all. Again, it's impossible to follow the wiring on the picture.

I was due to have a meeting with the chap from the chapel tomorrow, but it's been postponed due to a funeral. He may just have a diagram prepared by the guy who installed it all. I should be so lucky!

[Brian Gaff]

I think if it were I I'd just get my own meter fitted, Say on one of the phases. It might cost to start with, but surely you then have no middle man trying to soak you for what they don't want to pay. It has to be possible as houses converted to flats do it all the time. Brian

[Chris Hogg]

Don't we know it!!

We only use heating in winter, obviously. There are three N/S heaters in the main room, together with three wall-mounted IR radiant heaters, several small oscillating IR radiant heaters, and several small portable oil-filled heaters. Only one of the N/S heaters was in regular use last winter.

As our 'landlord', I think it would be illegal for the chapel to sell us electricity at a higher price than they pay for it, but IANAL. But I agree, there's much to be discovered as to how they work out our bills. I see nowhere where the chapel's own electricity use is recorded, for example.

Discussions are 'on-going'. The chapel people are talking about getting a new supplier, via their 'broker' (?). It worries me a bit that if they don't understand the existing set-up, they won't be able to specify exactly what they, or we, need.

If we have got, or can get E7 or its 3-phase equivalent, it may be cheaper to run the three N/S heaters at night, obviate the need for all the little portables during the day, and actually save money. The Archive is only open four days per week, mornings, so keeping it warm

24/7 is not necessary for human comfort (but may be necessary for document preservation).

Over our dead (and frozen stiff?) bodies!!

[Andy Burns]

You can get the gist of it,

clearly everything goes through the supplier's meter, so that's what will generate the amount on the bills.

Their "private" 3ph meter looks like it feeds the DB2/DB3/DB4 boards looks like 9x SH on blue phase and 5x SH on yellow phase

lots of classroom, staffroom, toilet stuff seems to be on red.

perhaps all "your" stuff is on DB1, which is a 3ph board, and they simply subtract "their" readings from WPD's reading and charge you what's left?

but if anything on DB1 isn't "yours" then it won't be correct, is your space on the storage heaters?

[Andrew]

Are there no other more-modern (=insulated) buildings that you could decamp to ?.

[David Wade]

I assume so. My dad had ducted air storage heating installed on E7. Sadly as he worked for the local board they didn't do a proper load enquirey. Our house was the last on a long line of poles.

When the storage unit and the imersion kicked in the TV picture rollde and the lights when very dim. Next door complained ther flourencent lights refused to work at all.

They stuck a recording meter on the poll. It showed 180v so they split the house across two phases and stuck lots of danger labels all over the place. So we had E7 but only on two phaases....

Dave

[David Wade]

I haven't looked seriously at this, but could it be that you are not paying for the storage heaters at all because of the issue with spiting the E7 load? Does they actually get an E7 reduction because the differential on domestic rates is, for many, not worth having. i.e. the power companies give you a reduced evening rate, but the day time rate is higher than a normal tariff.

Getting rid of storage heaters and replacing with Air-2-Air heat pumps (commonly called split unit air conditioning) would reduce consumption. They typically have an efficiency of 350-400% when heating and don't waste power by storing heat you don't need.

Trouble is capitol cost is high...

Dave