UK How to set up multiple tariff sources?

Purvez · Dec 11, 2021

I want to do the following:

There are 2 separate supply circuits in the flat. One is Normal tariff which is available all the time. The other is Economy 7 tariff which is only available between midnight and 7am.

I want to wire a socket so that when Economy 7 is available it draws power from that circuit and at all other times it draws power from the Normal tariff circuit.

How can this be achieved? Thanks in advance.

James · Dec 11, 2021

Can you post a picture of your meter or meters?
and what do you hope to achieve by this?

mainline · Jan 10, 2022

Purvez said:
I want to do the following:

There are 2 separate supply circuits in the flat. One is Normal tariff which is available all the time. The other is Economy 7 tariff which is only available between midnight and 7am.

I want to wire a socket so that when Economy 7 is available it draws power from that circuit and at all other times it draws power from the Normal tariff circuit.

How can this be achieved? Thanks in advance.

mainline · Jan 10, 2022

Use a change over contactor

pc1966 · Jan 10, 2022

If the "cheap rate" is only on at certain times then it would be simple to have a change-over relay or contactor to swap a socket between the two.

However, you need to be sure of the total load (just a 13A socket, or double socket?) and also to think of what is plugged in and if it can cope with a short interruption as the change over occurs. Not everything is happy with that! (PCs or most things with computer control like washing machines).

Achieving a "no-break" changeover is far harder to do and really more in the realms of specialised redundant power changeover / UPS bypass for computer servers, etc.

timhoward · Jan 10, 2022

If a socket ends up with two sources of supply it needs labelling as such.

[ElectriciansForums.net] How to set up multiple tariff sources?

brianmoooore · Jan 10, 2022

Am I missing something here? All sockets in an installation with an E7 supply are on the cheap tariff when it's available.
The OPs question would be applicable if it was an off peak or white meter supply.

littlespark · Jan 11, 2022

Agreed. There’s different ways the E7 was set up.

Older types, the entire house was on cheap rate overnight, sockets, lights, everything.

Later on, the supply companies got wise and then only the heaters got a night rate, everything else was still standard.

timhoward · Jan 11, 2022

littlespark said:
Agreed. There’s different ways the E7 was set up.

Older types, the entire house was on cheap rate overnight, sockets, lights, everything.

Later on, the supply companies got wise and then only the heaters got a night rate, everything else was still standard.

I’ve never known for sure how to differentiate between the two and would be interested to know more. Do you have to look at a bill or is the metering different?

littlespark · Jan 11, 2022

I suppose you could work it out watching the meters….

Turn everything off at night and boil a kettle…. See which meter moves, the standard or off peak.

There might be an easier way, but I’m just heading out the door and that was a quick thought…..

Rockingit · Jan 11, 2022

Ask your energy company to fit a twin tariff (probably smart, which they have to do for free [I think...]) meter, problem solved.

brianmoooore · Jan 11, 2022

littlespark said:
Agreed. There’s different ways the E7 was set up.

Older types, the entire house was on cheap rate overnight, sockets, lights, everything.

Later on, the supply companies got wise and then only the heaters got a night rate, everything else was still standard.

That's the complete opposite of my experience. Off peak and white meter are the older tariffs, with two separate meters. Back in the day, it was common to fix two 13A sockets in the airing cupboard, one on the off peak circuit, and the other on the 24 hour supply. The immersion heater would normally be plugged into the off peak, but could be transferred to the other for emergency use during the day.
The E7 and similar tariffs came later, and are still installed today. Two of mine were fitted six years ago.
E7 tariffs have a single meter with two dials.