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

[Oldgreybeard]

The Teleswitch came out many years ago, replaced the older mechanical time switches that used to be used for the "white meter" system. I've seen one with a 1970's date on it, so they were certainly around 50 years ago. Worked well, and they were cleverer than they seemed, as each region responded to a slightly different on and off code broadcast on 198kHz, so the off-peak periods were phased across the country, so that the grid didn't have all the nation's storage heaters turning on at the same time.

Teleswitches were replaced with digital Economy 7 and Economy 10 meters from around 25 years ago, I believe. The digital meters usually required a contactor box to switch the storage heater circuit, as the fifth wire didn't have a very high current rating, only enough to safely operate a contactor. Our E7 meter that was fitted just over 2 years ago just uses a built-in digital clock. It provides the required timing jitter (to stop simultaneous switch on) by the inherent accuracy limit of the clock. Mine runs about 3 minutes fast, for example, so switches on at about 23:27 UTC, rather than 23:30 UTC.

[sharpener]

Our E7 meter that was fitted just over 2 years ago just uses a built-in digital clock. It provides the required timing jitter (to stop simultaneous switch on) by the inherent accuracy limit of the clock.

Are they still fitting these, or will they try to insist I have a smart meter when the radio teleswitch service is discontinued? What is the most recent date for that? I have seen a variety of announcements and the wikipedia article is not very up to date.

[Oldgreybeard]

Our E7 meter that was fitted just over 2 years ago just uses a built-in digital clock. It provides the required timing jitter (to stop simultaneous switch on) by the inherent accuracy limit of the clock.

Are they still fitting these, or will they try to insist I have a smart meter when the radio teleswitch service is discontinued? What is the most recent date for that? I have seen a variety of announcements and the wikipedia article is not very up to date.

I tried to get a smart meter fitted by SSE in 2019. They installed it but couldn't get it to connect, after several tries at changing things, fitting a better antenna box, etc. After a few months they gave up and fitted a digital E7 meter. The meter was made in 2019, not long before it was installed. It has a button on the front to scroll through various displays, including the peak and off-peak registers.

As between 10% and 20% of UK homes cannot have a smart meter, I would have thought that it makes sense to retain the option to have a new E7 meter. E7 is pretty much as good, perhaps slightly better for some, as any of the smart meter tariffs. My main gripe is the way some suppliers are seemingly refusing to accept new customers unless they have a smart meter. I don't think this is actually lawful, yet I've had a couple tell me over the phone that the reason they cannot offer us a tariff is because we don't have a smart meter.

[marshman]

__

[sharpener]

E7 is pretty much as good, perhaps slightly better for some, as any of the smart meter tariffs. My main gripe is the way some suppliers are seemingly refusing to accept new customers unless they have a smart meter. I don't think this is actually lawful, yet I've had a couple tell me over the phone that the reason they cannot offer us a tariff is because we don't have a smart meter.

Yes, this is a scandal and so is the fact that there is no central repository I have yet found for tariff information. There was a posting recently about an EDF 7p off-peak rate but yesterday I searched for this and cannot find it on the EDF site as I am not an existing customer.

If anyone knows how I can check if this would be best for the SW region and go about switching to it please let me know!

The comparison sites have all shut up shop (?because they cannot make any money from switching) and although I subscribe to switchd they have not had anything useful to say for months now.

Then I found a Consumer Council web site which looked hopeful but it turned out on close examination to be the CC for Northern Ireland(!).

IMO this should be a key function of OFGEM but as we all know they have been effectively captured by the industry.

[Oldgreybeard]

E7 is pretty much as good, perhaps slightly better for some, as any of the smart meter tariffs. My main gripe is the way some suppliers are seemingly refusing to accept new customers unless they have a smart meter. I don't think this is actually lawful, yet I've had a couple tell me over the phone that the reason they cannot offer us a tariff is because we don't have a smart meter.

Yes, this is a scandal and so is the fact that there is no central repository I have yet found for tariff information. There was a posting recently about an EDF 7p off-peak rate but yesterday I searched for this and cannot find it on the EDF site as I am not an existing customer.

If anyone knows how I can check if this would be best for the SW region and go about switching to it please let me know!

The comparison sites have all shut up shop (?because they cannot make any money from switching) and although I subscribe to switchd they have not had anything useful to say for months now.

Then I found a Consumer Council web site which looked hopeful but it turned out on close examination to be the CC for Northern Ireland(!).

IMO this should be a key function of OFGEM but as we all know they have been effectively captured by the industry.

I did contact OFGEM about this a few weeks ago, published the reply I had from them in another thread last week. Bottom line is that they aren't interested in either getting suppliers to clearly publish tariffs, or enforce the legislation that requires suppliers to accept new customers.

[dangermouse]

I love the way these threads drift away from the original topic into something esoteric like the history of E7 meters

Reading yr initial post I am prompted to recommend this link viewtopic.php?f=14&t=1401
and this one viewtopic.php?f=14&t=1290 as there is a lot of explanation there of various aspects of inverter installation, you can't just "splice in" to the meter tails as you suggest.

You will certainly need various RCDs and mcbs and very likely a second consumer unit to house them, especially if you want to use the UPS capability of the battery inverter, and this would probably involve some re-arrangement of your existing house circuits. As well as the "REC isolator" in the meter tails you might consider installing a Surge Protection Device at the same time.

There is a link in the above (and elsewhere more recently) to the IET guidance on earthing which you also need to know about.

Here is a more detailed list of questions which might help with sizing etc:

What is your incoming supply (phases, amps)
Have you got an earth rod (TT supply) or do you use the supplier's earth (TN-C-S/PME)?
Annual consumption peak (kWh)/off-peak (kWh)

I've been reading all the threads I can around this topic, including those linked above, thanks.

To answer some questions:

Mains supply is 100A single phase, with PME earthing (I think so anyway, there's an earth connection on the box that houses the main fuse). It's certainly not TT.
Consumption is average of 5.2kWh / day.
Heating is gas, hence the low electricity usage.

At first, I don't intend to make use of the EPS function of the inverter. From all that I've read, any circuits connected to the EPS output need their own earth, and the discussions on these forums about earthing are long and complex! I am not sure if I even have anywhere suitable to sink an earth rod. At the moment I want to focus on getting an inverter and batteries installed. Next stage will be PV on the roof.

When all that is up and running I can decide whether I want to move circuits onto the EPS output.

I think I've gathered that inverter needs to be connected to a new (or existing, repurposed?) circuit on the CU. It has to be protected by a RCD, and a type C MCB. The RCD should be 100mA (why the higher rating, when most are 30mA?) and the MCB should be curve C.

So if I can physically fit those devices into my existing CU (it does have a couple of slots free) I won't need a second CU, and quite possibly I can repurpose an existing circuit and avoid needing a "new circuit" (with all that entails) ...

[sharpener]

I did contact OFGEM about this a few weeks ago, published the reply I had from them in another thread last week. Bottom line is that they aren't interested in either getting suppliers to clearly publish tariffs, or enforce the legislation that requires suppliers to accept new customers.

I thought OFGEM had a statutory duty to promote competition, silly me.

When all that is up and running I can decide whether I want to move circuits onto the EPS output.

I think I've gathered that inverter needs to be connected to a new (or existing, repurposed?) circuit on the CU. It has to be protected by a RCD, and a type C MCB. The RCD should be 100mA (why the higher rating, when most are 30mA?) and the MCB should be curve C.

So if I can physically fit those devices into my existing CU (it does have a couple of slots free) I won't need a second CU, and quite possibly I can repurpose an existing circuit and avoid needing a "new circuit" (with all that entails) ...

Sounds like you are well on the way esp if you have two or more spare ways in the CU.

100mA RCD and type C mcb spec is to provide discrimination. Ideally an earth fault or overcurrent on a final circuit will trip their protective devices before the ones feeding the inverter, important where like mine it feeds the whole house.

If you are never going to do that, only at most a few of its circuits for EPS, then a 30mA RCD is arguably better (and AFAIR specified somewhere), in that case you could just use a type C rcbo which would take up only a single way.

Must have switched neutral e.g. https://www.tlc-direct.co.uk/Products/WYNHXS1C20.html or you will need a separate lockable d.p. isolator.

[dangermouse]

Yup, 2 ways currently free in the CU and I can make another by combining two existing (low power) circuits if I need to. AFAIK, smoke alarms with a battery back up don't need a dedicated circuit.

Thanks for everyone's advice, I'm going to take the plunge and place an order today. 2 x PylonTech US2000 batteries from ITS and a SoFar HYD3600 inverter from TradeSparky. Solar panels can wait until I've got the inverter sorted out, I won't miss out on much as long as I get them up before spring.

[AGT]

I love the way these threads drift away from the original topic into something esoteric like the history of E7 meters

Reading yr initial post I am prompted to recommend this link viewtopic.php?f=14&t=1401
and this one viewtopic.php?f=14&t=1290 as there is a lot of explanation there of various aspects of inverter installation, you can't just "splice in" to the meter tails as you suggest.

You will certainly need various RCDs and mcbs and very likely a second consumer unit to house them, especially if you want to use the UPS capability of the battery inverter, and this would probably involve some re-arrangement of your existing house circuits. As well as the "REC isolator" in the meter tails you might consider installing a Surge Protection Device at the same time.

There is a link in the above (and elsewhere more recently) to the IET guidance on earthing which you also need to know about.

Here is a more detailed list of questions which might help with sizing etc:

What is your incoming supply (phases, amps)
Have you got an earth rod (TT supply) or do you use the supplier's earth (TN-C-S/PME)?
Annual consumption peak (kWh)/off-peak (kWh)

I've been reading all the threads I can around this topic, including those linked above, thanks.

To answer some questions:

Mains supply is 100A single phase, with PME earthing (I think so anyway, there's an earth connection on the box that houses the main fuse). It's certainly not TT.
Consumption is average of 5.2kWh / day.
Heating is gas, hence the low electricity usage.

At first, I don't intend to make use of the EPS function of the inverter. From all that I've read, any circuits connected to the EPS output need their own earth, and the discussions on these forums about earthing are long and complex! I am not sure if I even have anywhere suitable to sink an earth rod. At the moment I want to focus on getting an inverter and batteries installed. Next stage will be PV on the roof.

When all that is up and running I can decide whether I want to move circuits onto the EPS output.

I think I've gathered that inverter needs to be connected to a new (or existing, repurposed?) circuit on the CU. It has to be protected by a RCD, and a type C MCB. The RCD should be 100mA (why the higher rating, when most are 30mA?) and the MCB should be curve C.

So if I can physically fit those devices into my existing CU (it does have a couple of slots free) I won't need a second CU, and quite possibly I can repurpose an existing circuit and avoid needing a "new circuit" (with all that entails) ...

Do you have a suspended timber floor?

What about hitting a rod inside the property under the floor?
That’s what I’m planning as it means I can put the rod virtually under the consumer unit, no visible conductor to see, no slabs to lift..
works for me in my Victorian property as it’s just sand under the boards.. it’s accessible for inspection so just thought I would mention it in case it’s an option..