How much can I practically/legally DIY, and other newb questions

[John_S]

Do you have a smart meter.
When mine was installed, they also installed an isolation switch between the smart meter and the consumer unit free of charge.

[dangermouse]

Well my plan is go move to Economy 7, to charge the batteries overnight. I think with E7 you have to have the old fashioned meter with a timer on it? But EDF are going to have to change the meter either way, I am trying to enquire whether they'd fit an isolator at the same time, but it's slow work getting information from them!

[Oldgreybeard]

Well my plan is go move to Economy 7, to charge the batteries overnight. I think with E7 you have to have the old fashioned meter with a timer on it? But EDF are going to have to change the meter either way, I am trying to enquire whether they'd fit an isolator at the same time, but it's slow work getting information from them!

That's what we do, and E7 is ideal for this, as having 7 hours of off-peak makes it easier to juggle all the things that need to be on, or charging, during the cheap period. Used to be that isolator switches were the property of the consumer and the responsibility of the consumer to install. Not sure if that's changed or not. Chap that installed our charger asked beforehand if we had one (we did, as we have a TT supply with a long cable to the house) and told me that he'd not have installed the charger unless we had one fitted before he came.

[Countrypaul]

Well my plan is go move to Economy 7, to charge the batteries overnight. I think with E7 you have to have the old fashioned meter with a timer on it? But EDF are going to have to change the meter either way, I am trying to enquire whether they'd fit an isolator at the same time, but it's slow work getting information from them!

We have E7 and a Smart meter, there is no separate circuit for E7 though, so if you want to make use of E7 you need things on a timer.

[Oldgreybeard]

We have E7 and a Smart meter, there is no separate circuit for E7 though, so if you want to make use of E7 you need things on a timer.

Just as a heads up, during our abortive attempt to get a smart meter, the meter fitter that tried several times to get the meter to work did mention that there were now smart meters that had the fifth wire for E7 and that had a manual reading capability for the two tariff periods. Checking the list of smart meters shows there are now quite a few fifth wire E7 ones available now.

The list is here (scroll down to SMETS2) and all the meters listed as "5 terminal" are Economy 7 capable, with a switched output to drive a E7 switched circuit contactor: https://www.smartme.co.uk/smets-2.html

Could be handy as a backstop, as maybe these E7 smart meters fall back to being standard E7 meters if they lose the signal?

[dangermouse]

We have E7 and a Smart meter, there is no separate circuit for E7 though, so if you want to make use of E7 you need things on a timer.

Thanks, interesting information. In my current plan, the only thing on a timer would be the inverter programmed to charge batteries during the E7 period.

Just as a heads up, during our abortive attempt to get a smart meter, the meter fitter that tried several times to get the meter to work did mention that there were now smart meters that had the fifth wire for E7 and that had a manual reading capability for the two tariff periods. Checking the list of smart meters shows there are now quite a few fifth wire E7 ones available now.

So the E7 meter has a switched output that's only live when E7 is active, but presumably power delivered through the normal output is charged at the E7 rate during the off peak times? So if your appliances (or inverter) are on a timer, you don't need the 5th wire?

[Oldgreybeard]

So the E7 meter has a switched output that's only live when E7 is active, but presumably power delivered through the normal output is charged at the E7 rate during the off peak times? So if your appliances (or inverter) are on a timer, you don't need the 5th wire?

Yes, that's right. The fifth wire is used to control a separate E7 circuit, via a contactor. This arrangement is normally used in homes that have storage heating, where the storage heater circuit was kept separate and switched by the E7 contactor. Installations like this have two consumer units, one for the always on supply, one for the E7 storage heaters. The whole house still gets charged at the cheap rate during the off-peak period, though. The E7 switched circuit was just a way to make sure that storage heaters were only ever charged up during the cheap rate slot.

[Countrypaul]

So the E7 meter has a switched output that's only live when E7 is active, but presumably power delivered through the normal output is charged at the E7 rate during the off peak times? So if your appliances (or inverter) are on a timer, you don't need the 5th wire?

If on the old fashioned meters (spnning disc type), only the devices on the E7 switched output are charged at the E7 rate (as the E7 meter is seperate), everything else is at the normal rate. So one advantage of the newer meters is that anything on during the E7 period is charged at the lower E7 rate.

We originally had 2 meters one for E7 devices such as storage heaters and one for everything else. When we renovated and moved the meters we were given a single meter that had two rate bands one for the E7 period and one for the rest. When we got a smart meter it seems to have 2 bands (though I am not 100% sure - it could just be that they can tell each half hour and work things out from that.

I believe you could substitute E10 for E7, the timings for the clock switches in the old meter would have to be manually reset.

[sharpener]

So the E7 meter has a switched output that's only live when E7 is active, but presumably power delivered through the normal output is charged at the E7 rate during the off peak times? So if your appliances (or inverter) are on a timer, you don't need the 5th wire?

If on the old fashioned meters (spnning disc type), only the devices on the E7 switched output are charged at the E7 rate (as the E7 meter is seperate), everything else is at the normal rate. So one advantage of the newer meters is that anything on during the E7 period is charged at the lower E7 rate.

I believe you could substitute E10 for E7, the timings for the clock switches in the old meter would have to be manually reset.

Not quite. There are also meters controlled by signals broadcast at 198 kHz from Droitwich (the Long Wave Light Programme transmitter of my youth) - see https://en.wikipedia.org/wiki/Radio_teleswitch.

We have a two-rate "spinning disc" meter with a separate teleswitch control receiver box made by Horstmann and fitted downstream of the meter. It has a nominal 2A output to switch the meter between registers and two 80A load outputs. One is live all the time and feeds the whole house, the other (unused) is intended for e.g. storage heaters as upthread.

Later radio teleswitch meters incorporated the receiver inside the meter housing, Cambridge Consultants developed one such for Landis + Gyr ? in the '90s.

This system is due to be discontinued because of an alleged shortage of replacement transmitter valves, what will be substituted for people like us who cannot have a smart meter because they get no signal has not been announced. I suppose we could revert to timeswitches with spring reserve which was the original method, I think they stopped using them for new installations because of the maintenance requirments and/or liability to tampering.

[Countrypaul]

So the E7 meter has a switched output that's only live when E7 is active, but presumably power delivered through the normal output is charged at the E7 rate during the off peak times? So if your appliances (or inverter) are on a timer, you don't need the 5th wire?

If on the old fashioned meters (spnning disc type), only the devices on the E7 switched output are charged at the E7 rate (as the E7 meter is seperate), everything else is at the normal rate. So one advantage of the newer meters is that anything on during the E7 period is charged at the lower E7 rate.

I believe you could substitute E10 for E7, the timings for the clock switches in the old meter would have to be manually reset.

Not quite. There are also meters controlled by signals broadcast at 198 kHz from Droitwich (the Long Wave Light Programme transmitter of my youth) - see https://en.wikipedia.org/wiki/Radio_teleswitch.

We have a two-rate "spinning disc" meter with a separate teleswitch control receiver box made by Horstmann and fitted downstream of the meter. It has a nominal 2A output to switch the meter between registers and two 80A load outputs. One is live all the time and feeds the whole house, the other (unused) is intended for e.g. storage heaters as upthread.

Later radio teleswitch meters incorporated the receiver inside the meter housing, Cambridge Consultants developed one such for Landis + Gyr ? in the '90s.

This system is due to be discontinued because of an alleged shortage of replacement transmitter valves, what will be substituted for people like us who cannot have a smart meter because they get no signal has not been announced. I suppose we could revert to timeswitches with spring reserve which was the original method, I think they stopped using them for new installations because of the maintenance requirments and/or liability to tampering.

I thought the radio teleswitch was a recent development, certainly don't remember seeing any in the 60s and 70s before I left home (that used storgage heaters on the seperate meter).

Probably just shows that there are likely to be many more variants than mght be expected.