Connecting backup power to your house Featured

TransferSwitchOutputTailsInstalled.jpg has quite bad camera shake.

Bill

My solar 12V and 19V supply for 200Ah battery, hub and computer in the event of a power cut.

You mentioned you have two consumer units, Given the power output of the generator:

I had wonder about splitting my CU into two CUs, one being high power & non-essential circuits and the other CU having essential circuits and low power circuits on 6A RCBOs for things like CCTV, Smoke alarms, CO alarms, Intruder alarm, all lighting ciruiots that are all LED based and of course the boiler circuit (NOT IMMERSION!) and possibly a freezer if the genny can support that rather inductive load.

Then the transfer switch could be used on the one CU unit greatly simplifying power cut management and reduce teh risk of humans in teh house overloadign the genny.

and of course yoru ADSL/Fibre/VDSL modem/router & switch plus laptops..... and VOIP telephones

In my case I have one dedicated to house circuits, and the other is Garden / Outbuilding circuits. (the logic being that the external ones are those most likely to import nuisance trip problems due to high earth leakage - so being able to isolate and remove them from the system could be handy.

Yup, a good plan that can make things much easier to manage. The split will be partly dictated by the size of the generator though.

(you could probably achieve similar results within a single CU just with a quick diagram showing which circuits to power down)

The transfer switch must isolate the whole house installation from the grid so that you can safely inject power into the house without any back feeding risk. So not so easy to use on just one CU. (and to be fair, the main switches on the CUs make for easy isolation of any one CU (or both)

Damn! You've pricked my conscience! I have a generator in a shed with (I'm embarrassed to admit) a come-to-Jesus cable. The plan being to isolate the shed on the main CU, connect and start the generator, return to the house to isolate the supply and trip all MCBs, then turn-on the MCB to the shed and enable the necessary circuits. I'm aware of the possible risks, to self and line workers, so have been meaning to add a changeover switch since I first put a buried cable to that shed, but we haven't had any serious power outages so it's always been pushed down the (infinitely-long) job list. Maybe the time has come ... once the current jobs have been completed.

Yup not good is it! OK being too lazy to go and take the photo again (it would mean walking 7m!), I have done an unsharp mask on it, rescaled it and up loaded it again. Try that.

I've bought a couple of hamsters, a Mr & Mrs, and a big wheel. Do I still need a transfer switch?

No regular supply of new Hamsters.

Being serious for a moment, on the news last night Germans are demonstrating about cost of living and shortages of power in Winter. It does seem to me that as per usual, most countries have paired down their reserves and then, faced by any catastrophe, be it in the form of a war in the country of supply or some natural disaster, then the market forces push the prices up, Here in the UK we decommissioned a lot of gas storage some time back, now we need it. As for making a house run on other power sources. That could be quite hard to do. I gather for example if you are going to not be able to live due to reliance on machines at home, then they will put in a generator etc or not cut off that part of the street. Seems to me that we all have neglected more efficient ways to store electricity when demand is low and then push it out during high demand periods, whether that be by pumping water up to the top of a hill or batteries, I think something here has to be done, or how on earth will we get on top of fossil fuel use?

I mean a diesel generator in your garden is hardly quiet, green or very neighbour friendly. Brian

You keep saying this, Brian, without specifying which hill you are talking about, or which batteries either.

Ironically, when I started writing that page, I included sections on other ways of hooking up a generator - extension leads etc, and also including what I called a "widow maker cable" :-)

I decided it was losing focus on the purpose of the page, so took it out in the end.

Yup, "non conventional" connection arrangements, can be safe (ish) when the use is by skilled people who understand what they are doing.

The danger comes when you need someone else to use the setup.

Interesting, thanks. A while back I was looking for an automatic version, for a houes battery. In theory a genny transfer switch would have been suitable, but didn't manage to find anything affordable/domestic scale (also quite space constrained).

What's the Part P situation with a DIY install like this?

Theo

In message snipped-for-privacy@mid.individual.net>, Tim Streater snipped-for-privacy@greenbee.net writes

Sadly the suitable hills mostly aren't where such installations are welcomed by the neighbours or where surplus power is available.

I suppose it might be a selling point for windmills if you could link them to suitable reservoirs but you still have the intermittency issue.

Switchable nuclear seems best. Preferably owned by this country's tax payers.

Brilliant. Thanks John.

This was on my "to do" list many many years ago! I'm sure I queried it with the group at the time; possibly after we shut the house down for about 3 days while re-wiring it and lashing up a small generator from Makro to provide power to the Koi pond... that was aout 17 years ago, I still have that 2-stroke genny un-used in the shop warhouse.! Also more than likely the plan was re-ignited in the lead up to the great un-known of the end of the Mayan callendar, a bit like the Y2K computer bug paranoia.

In my way of adding wires everywhere "just in case", when I wired up the extension 5 years ago I ran a 6mm sq. wire from the C.U. to the garage "Just in case" I might add an E.V. charging point at some point in the future, I could use that as I doubt I'll be getting an E.V. before they're "extinct" and replaced by Hydrogen or whatever.

Presumably some portable generators can have an external exhaust port so it could run in the garage away from prying eyes?

Only the other week I was once more looking into whether an LPG generator and gas bottle might be more versatile in the long run than petrol or diesel with regards to fuel longevity and refueling requirements, although there seems to be a significant shortage of generators on many web sites, certainly dual-fuel lpg/petrol seem to be quite scarce...

Perhaps this is my new project?

Would be nice to know all central heating pumps and lights could run in the event of a winter blackout. Our standing house load in the summer is around 600W so 2.5 to 3KVA genny would keep us ticking over.

Cheers - Pete

And how much water would be required or the capacity of the batteries required. There is nothing stopping Brian from investing in batteries to power his house during a power cut.

EV batteries are around £85/kWh so only around £20 billion to provide backup for a nationwide 8 hour power cut (ignoring all the other costs associated with such a large battery stack :)

When we all have electric cars sitting in our driveways the problem with battery storage will disappear. As long as you don't want to drive any distance the car could power your house for days.

Not looked into that aspect particularly, although it was not a feature I have seen touted. Generator enclosures do exist - but they are more "vented" rather than ported.

Yup, I had been thinking about making provision to carry on working through extended power cuts for some months, but only recently got round to getting round to actually doing anything. Inverter generators in general are in short supply now. (I had one order cancelled on me for lack of stock even though the supplier initially thought they could get it)

Indeed. My requirement was lights, CH (assuming there is gas!), and my full IT and comms load, plus some "austere" capability for household stuff. So with 3kW to play with one should at least be able to run a microwave, and possibly a smaller kettle. Presumably for a few hours at a time. I have UPS capacity to keep stuff going long enough to switch power sources.

(I have propane and a "camping" style three ring hob that can also be pressed into service)

There are some quite nice "whole house" UPS style battery inverters coming along (Youtube channel mikeselectricalstuff just did an in depth review and teardown on a new Bluetti bit of kit that looks very well thought out and well made. The price is eye watering, but does reflect the quantity and quality of the engineering that went into it)

Yup I suspect not worth it with a genset unless you also have auto start on that.

Fronting critical stuff with a UPS ought to ease the transition to local power.

I have a suspicion that if applying the "letter of the law" it falls neatly between the cracks!

The current (newer "low fat") part P only has the following notifiable jobs:

So one could argue that connection from the input socket to the switch is not a "new circuit" in the conventional sense. The CU was not changed, and mounting an electrical accessory on the outside wall no longer counts as a special location.

Given there is pressure in the EU to reduce peak electricity consumption by 5% we might be reverting back to towing a diesel generator behind you!

Bottled LPG is expensive. I did think Natural Gas was the way to go, but it's probably currently diesel.

If you want dual fuel then perhaps a Kelvin K2?

If you limit your power needs, why not a UPS. If endurance is needed then add extra batteries?