Economy 7 supply

[Empire]

Hi All,

I have just completed an EICR on a new (2017) conversion and noticed the E7 looked unusual.

Is this the norm now to connect E7 to the main board feed from the meter?

There is only 1 appliance in the flat requiring E7 and that's the tank with 2x immersion heaters. Both are connected to the same supply at the board.

Surely the main electrical supply doesn't now switch off overnight and E7 take over?

I've attached a pic but would appreciate your opinions.

 

[brianmoooore]

I presume we're talking about the top meter only?
It's a dual rate meter and powers up L5 when off peak is available.
The devices requiring off peak electricity can be fed from a second CU (or space in the main CU, if big enough), fed from L5, or from the main board, using their own time switch.
It looks like the second option has been taken here. Disadvantage is that it requires the DNO off peak switching and the local timeswitch to be kept synchronised if full price operation of what should only be using off peak is to be avoided.

 

[buzzlightyear]

The isolator is not on e7 so looking at the pictures.

 

[Empire]

both meters are connected in the same way.

yes, I'd run a second supply from the meter to the E7 accessories but I've not seen both L4 & L5 joined together at the isolator before.

 

[brianmoooore]

How are they joined? L4 feeds the board and L5 is unused, or am I missing something?

 

[Empire]

Isolator is a 2gang switch and L4 & L5 are joined together.

 

[brianmoooore]

Isolator looks like a four gang to me, with three gang in use.

 

[Empire]

then the E7 was on at 11am this morning because both we live.

 

[brianmoooore]

Have you had the cover off of the isolator?

 

[Empire]

yes been inside isolator. I expected 1x L to be live and 1x L to be not. Both were live and assumed they were unexpectedly joined together to use the 1x L feed to the board and 'time share' its use. The client was sold the flat on the basis of it having an E7 connection.

So, I'm wrong about the isolator and the L's should be separated, then that means the E7 was on, perhaps permanently and not connected to anything.

Thanks, that's helped.

 

[brianmoooore]

You need to check whether the meter says R1 or R2 at different times of the day.
L5 should only be live when R2 is displayed. L4 should be live all of the time.
Ideally, there should be a link between the two neutrals at the bottom of the isolator.

 

[westward10]

Am I misreading this but there is nowt connected from L5 at that four pole isolator.

 

[pc1966]

It looks like the meter and isolator are wired for both permanent L and off-peak L, but the installation is only using the normal (permanent) supply? Or am I missing something really obvious?

 

[brianmoooore]

The installation gets full price and off peak electricity at the appropriate times of day (hopefully), depending on whether the display shows R1 or R2, but the installer chose to use a local timeswitch for the water heating, rather than the DNO switch.

 

[Empire]

Thanks all, this has been helpful.

The client told me the property had E7. After testing it looked like L4 & L5 were connected together, despite the separation at the isolator, because L5 was live during testing. As there is no onward connection from L5 I assumed (Wrongly) that some form of sharing was taking place with the onward L4 as I'd not seen an allegedly active E7 configuration like this before.

Client is not happy to be told there is no E7 connection to her flat .

 

[brianmoooore]

What makes you think there isn't?
The definitive answer will be found on their electricity bill. If it shows R1 and R2 and they have different rates per kWhr, then they have E something, if not E7.
How did you test L5 was live?

 

[Grant1987]

What makes you think there isn't?
The definitive answer will be found on their electricity bill. If it shows R1 and R2 and they have different rates per kWhr, then they have E something, if not E7.
How did you test L5 was live?

Looking at this it is hard to tell and not the conventional way of economy 7 this seems like the DNO has connected the meter tails. I installed hundreds of heaters and on rare few occasions customer had issues with electric bills not being on dual tariff due to energy supplier mishaps. Easiest way to find out is get voltmeter readings at heater during peak hours which should be 0V unless they are the smart heaters which operate on peak and off peak the off peak should not have voltage untill off peak is operational usually 00:00-07:00 although they do vary ask your supplier for accurate times

 

[loz2754]

Some off peak tariffs are not restricted to the usual after midnight time slots. Perhaps you tested the L5 (which would normally be labelled L2) at a time when the off peak was switched on?

 

[Grant1987]

Some off peak tariffs are not restricted to the usual after midnight time slots. Perhaps you tested the L5 (which would normally be labelled L2) at a time when the off peak was switched on?

Yes good point there, dual tariff electric is a minefield and from my experience even the energy suppliers are not too clued up I learnt on the job and spent countless hours fault finding so many different set ups and permutations just got to work through it methodically

 

[littlespark]

L4 is normal rate, L5 is off peak. It may be like this so that a second board for heaters would come from L5, but in this instance, it’s linked to L4 on customer side, meaning the whole house will run on L5 during off peak hours.

The will connect the tails like this to all dual rate meters make them all the same, just for ease.
wont always know how the customer equipment is configured.

 

[loz2754]

L4 is normal rate, L5 is off peak. It may be like this so that a second board for heaters would come from L5, but in this instance, it’s linked to L4 on customer side, meaning the whole house will run on L5 during off peak hours.

The will connect the tails like this to all dual rate meters make them all the same, just for ease.
wont always know how the customer equipment is configured.

How are they joined? L4 feeds the board and L5 is unused, or am I missing something?

Am I misreading this but there is nowt connected from L5 at that four pole isolator.

How is L4 linked to L5 on the customer side exactly?

 

[snowhead]

Unless the meter has been programmed to act as a 4 wire meter where all output is metered at rate 2 in the Off peak period, then part of the useage will be charged at rate 2 but part will still be charged at rate 1 in the Off Peak period with L4 / L5 linked, depending on how the load splits over the 2 meter outputs.

 

[7029 dave]

The Off peak set up is very much standard and correct from the energy supply, using an integral meter for off peak switching, 5 terminal wired through the correct off peak isolator, which has no load connected to it. If you look at the top NN , that is to give two N connections the bottom part is linked across, L L in picture L off peak (not used) L 24hr supply.

They have used their own time clock in the CU to switch over presumably to fall inline with the meter off peak times as the whole 24hr supply goes over to off peak too, it could be E10 that gets an afternoon boost also early evening too.

However full off peak switching has been provided by the energy suppler, its there if needed .

 

[littlespark]

How is L4 linked to L5 on the customer side exactly?

Possibly a copper link between the outgoing terminals. Can't tell without the cover off.

 

[brianmoooore]

Economy 7 or 10 is a tariff, and depends entirely on a dual rate meter being fitted. Nothing that comes after the meter is anything to do with the tariff as such, just how you choose to use it.
I have three supplies to my property, all of which are Economy 7, but there are only two tails from each meter, since all Economy 7 switching is done by time switches owned by me, and the 'time switch' built into the meter is only used to change the display.
The meter shown in the pic. is a dual tariff meter, which should display R1 or R2,depending on the time of day, and this should be shown on the customer's electricity bill.
R1 an R2 may or may not be charged at different rates, depending on what the customer has chosen. Two of my supplies are currently on tariffs where R1 and R2 are charged at exactly the same rate, since the proportion of night time consumption on what they supply isn't currently high enough to justify the premium that would be charged on the R1 rate.

 

[7029 dave]

The ops meter is a 5 terminal dual tariff meter, blue button to read both rates, as explained the off peak has not been used, but is there if a dedicated Off peak CU is needed.

 

[Empire]

Thank you all,

I've read through twice and didn't know E was so complicated. Essentially then, this installation could have some form of E linked through the meter/isolator and run whole property using L4 as there is no separated E feed from the isolator on L5.

 

[brianmoooore]

The electricity on L4 is charged at full rate (R1) for 17 hours a day, and at the cheaper rate (R2) for the remaining 7 hours. L4 is permanently live.
L5 is only live for the 7 hour period, and only at the R2 rate. During that 7 hour period you can use the electricity on L4 or L5. It's exactly the same electricity and exactly the same price.

 

[Empire]

Thank you Brianmoooore,

I've lived and I've learned.