Changeover switch: how to go about it ...

[ToughButterCup]

If @Jeremy Harris says he has a regret during his house build, I'd be daft not to learn from that experience. Here's what he said

 

Quote

As an aside, one thing I REALLY regret is not having split our house wiring into essential and non-essential circuits, with separate feeds for each.  I would then have fitted a changeover switch on the essential circuit to allow either a generator or battery bank and inverter to provide power in a power cut.  It would have been easy to do when running the first fix electrics, but a real pain to do now.

 

We are planning to have a backup battery system sometime soon(ish). But not yet. Prices need to come down a bit I think.

Since we are planning to have two Consumer Units, will it be possible to put what we consider the essential circuits on one board, and the not-so essential circuits on the other board ? ....

 

For example

• Oven, hob, fridge freezer, mvhr supply, washing machine, 5 amp lighting circuit and a few kitchen sockets on one board
• and the rest on the second board?

[Markblox]

44 minutes ago, AnonymousBosch said:

If @Jeremy Harris says he has a regret during his house build, I'd be daft not to learn from that experience. Here's what he said

 

 

We are planning to have a backup battery system sometime soon(ish). But not yet. Prices need to come down a bit I think.

Since we are planning to have two Consumer Units, will it be possible to put what we consider the essential circuits on one board, and the not-so essential circuits on the other board ? ....

 

For example

• Oven, hob, fridge freezer, mvhr supply, washing machine, 5 amp lighting circuit and a few kitchen sockets on one board
• and the rest on the second board?

It might be just as easy to have the whole lot on a changeover switch and in the very rare occasions you have an outage just monitor closely your usage. You can even turn off individual circuits if you don't trust yourself or if you have some big loads that would otherwise become live.

A normal changeover switch is used with a genny but would normally be part pf the package with a lithium battery/inverter. 

Will any PV be grid tied or can it charge the battery direct?

[SteamyTea]

Is an oven and hob really essential?  They are large draws on the system.

I have had one power cut that lasted 4 hours, made my tea with my camping stove.

Keeping the house warm and bright is essential for a multi-day outage.  

[vivienz]

Always handy to have a bit of spare charcoal for the bbq.

[ProDave]

For this application a changeover switch loos like this https://www.ebay.co.uk/itm/ESR-SECO125-125A-CHANGEOVER-SWITCH-GENERATOR-TRANSFER-INDICATOR-SINGLE-PHASE/253453017862?epid=15015581863

[SteamyTea]

Kenneth knew about switching.

[joth]

5 hours ago, AnonymousBosch said:

If @Jeremy Harris says he has a regret during his house build, I'd be daft not to learn from that experience. Here's what he said

 

 

I had assumed I'd try and split loads in this way too (like you, future proofing in case the battery system I eventually get supports it) but I've gone off it for a number of jumbled thoughts

- automatic change over switches are extremely expensive and sensitive electronics would still need their own UPS anyway

- I really can't figure a sensible policy for what circuit to use where. Should bedroom sockets be backup or not? I'm very likely to be annoyed whichever I decided.

- if running 2 grades, it'd be nice to have nonessential devices on a contactor so they all just turn off when I'm not at home (remove vampire loads), bit that adds another dimension of requirements and makes it even more likely I'd be annoyed at getting it wrong. 

- all high load devices are occasional use manually controlled devices anyway. So I can just as easily just not use them. It's not that hard to remember not to mow the lawn during a power cut

- manual change over switch, I can just cut out high load circuits manually (or even put them on a contactor) at same time

- power cuts in the middle of a town are very rare and not worth over thinking anyway

 

All that said, I see Tesla powerwall now does have the option of backed up circuit, so maybe it is something I should think about again. Having the upstairs CU on the backed up circuit maybe easiest, as that will feed MVHR, lighting, AV&HA&security, and could easily do the fridge/freezer too.

 

Related, would it be appropriate to have a spare core in the SWA from meter distribution board to each CU, so each location could easily have access to both supplies? Initial it would be unused, but could easily be commissioned later. This very neatly avoids having to think much about it at all, AFAICT

[TonyT]

I have a 125 amp single phase changeover switch that I manually operate when we have power failures, it’s linked to a small inverter generator in the garage that is on a commando plug and socket.

 

prone to power failures in my area so this saves us grief.

 

i can go and start the generator in the garage, let it warm up for a minute or 2 and then operate normally.

Family know it’s 2kW max so it’s really has central heating, lighting and small power.