Were you a Boy Scout?

It depends on the sort of person you are. Did you dig up the garden to install a fall out bunker during the cold war, now probably an underground pond or the centre of your mushroom business or did you consider, post apocalypse, the last people you would want to share a scorched earth with would be exactly those paying out huge sums for such hole in the back yard. But the energy crisis is a little more guaranteed and less costly to prepare for. Essentially it is like the the Boy Scout analogy. “Be Prepared”. Apologies to any Girl Guides. An auxiliary generator is not rocket science and installation is neither expensive or difficult.

There are two simple avenues: manually switched transfer(MST) or Automatically Switched Transfer (AST, sometimes referred to as AMF[automatic mains failure]). There is ONE MAJOR CAVEAT though. This is playing with the mains supply to the house between the electricity meter and the consumer unit. Legally, and practically, this is beyond the DIY enthusiast and should be done by a qualified electrician. It should take little more than an hour and the certificate provided will be useful for the insurers in the event of a future conflagration.

gen backup

First you need to ascertain your minimum power requirement. The fridge, freezer, central heating, lights and possibly water pump if you are on a private supply. A minimum requirement for a house is probably about 3kw. The cost of a manual transfer switch and 

3.5kw manual start generator is around £800 incl vat but plus installation. Hardly going to break the bank. The generator will run for about 10 hours and can be refilled, due care

being taken. Hot generators and petrol need to be treated with caution. As in the diagram the generator should be sited outside and consider that generators are heavy so wheels (about £70 extra) may be appropriate depending on your circumstances. Also consider the noise if you are close to neighbours. As they shiver in the cold they may take exception to a noisy generator next door! If you have a generator already a manual switch is around £250 plus installation.

The alternative is an automatic switched system which requires an electric start generator with remote sensing input. The switch will recognise the power outage and send a signal to the generator which will start up and in a few seconds take over the load. When the power comes back it will simply switch back to the main supply and in about thirty seconds the generator will turn off. The cost of this luxury is about £1800 plus installation. There may be an added cost of an exhaust pipe for the generator if it is sited in an outbuilding or garage. The added advantage is that this model is 5.3kw so will cook the Christmas Turkey! This system also comes with AVR(automatic voltage regulation) which removes spikes in the power supply which could damage sensitive electronic equipment such as computers. However you can get surge protection extension cables for computers reasonably cheaply if you prefer the more economical option. Another alternative is to go for a larger 4.95kv Manual switch system with AVR for £1154 incl vat. Good automatic systems include a trickle charger for the generator battery which protects against the possibility of the embarrassment of a failure of the system. The neighbours will notice quicker than even you!!

A useful web site is http://generators.co.uk or http://mainsfailure.com. I have no contact with either site and many more are available through Google.

Go on, splash out and really upset your neighbours as they freeze in front of one candle on the coldest night of the year.



About Dougal Quixote

Slightly mad. Always believes a cup is half full so continues to tilt at Wind Turbines and the politicians that seem to believe it is their god given right to ruin Scotland for a pot of fool's gold.
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4 Responses to Were you a Boy Scout?

  1. Dave Ward says:

    A few comments:

    1) Most of the lower cost generators have aluminium windings, rather than copper. From my years in telecoms, I know this is a false economy – the material may be fine for large conductors and buss-bars, but will suffer from fatigue and corrosion in a small generator. And unlike copper, it can’t be easily repaired by soldering.

    2) Unleaded petrol is well known for not keeping over long periods. Either a) use an additive, or b) drain the fuel tank and carburettor after running, and keep it in a sealed jerry can. This might go against the ideal of quick starting, but the alternative – blocked jets due to gunge in the tank, as I have experienced – is less appealing. Petrol engined generators can be ordered (or converted) to run on Propane gas, which solves this problem. In either case keep a reliable torch nearby so you can see to re-fuel in the dark.

    3) Any permanently wired transfer switch has to be capable of carrying the FULL rated current of the mains supply, which will be considerably more than a portable genny can produce. Most domestic supplies are in the range of 60-100 amps.

    4) Whilst a 3KW generator will cope with the sort of loads you mentioned, it might not be too happy starting them all at once. Motors (particularly a borehole water pump) have a very high surge requirement – even small fridge/freezers can require several times their normal running load. I suggest that a manual transfer switch is better for this scenario, as you can turn off such devices before starting and transferring the supply. Then turn them back on one by one. Only go for a fully automatic system if you can afford a largish generator. In this case it would be sensible to spend a bit more and get a diesel version. Diesel doesn’t “go off” like petrol, but beware of waxing in cold weather. Fuel companies change the composition of fuel oil during the year, and you don’t want to have a load of “summer” blend in a subzero winter.

    5) Security – I can foresee a very real risk of theft, if power cuts do become more common. And, of course, the sound of a small engine running and lights on, when everyone else is in darkness, will be a dead give away! Locating a generator in a secure outbuilding is worth consideration, BUT it must have ample ventilation, and an external exhaust pipe.

  2. I agree with all your comments. If an auto switch, it really needs designing to accommodate the top load. A manual switch has the advantage that you can go around and switch off surplus power requirements before you switch over. Your comments about petrol are more and more relevant as more ethanol is used. Additives can be used but are not a 100% solution. Annual servicing with a complete change of fuel would be a help. Alternatively it would be a good practice to run the system for an hour a month. This we always did with our main standby generator at my cold store but that was diesel. Mind you, as we are going, we will probably be using any generator on a regular basis!! Alternative to 5 is the biggest chain and padlock you can afford and a Doberman! Diesel generators does push the cost up noticeably. A specialist supplier will provide good sizing advice. I would probably suggest something like 5.7KW for a domestic house with a manual MTS. Hyundai do a competitively priced Diesel, electric start, silenced generator. It all depends if you want a pocket knife or a swiss army knife. For occasional events a simple pocket knife will be sufficient for many. If you expect days off grid then something more robust makes sense.

  3. Dave Ward says:

    “If an auto switch, it really needs designing to accommodate the top load”

    Auto or manual, the 3 position changeover switch still has to cope with whatever source is able to supply the greatest current. I’ve had some difficulty getting this point over to friends – in fact, at the moment I’m helping a friend with choosing a standby set. The one he’s chosen is actually substantially bigger than needed, and he’s had to buy a transfer panel which can cope with this, NOT the mains! I suspect you meant that with an auto panel the generator needs specifying to cope with top load?

    “Alternatively it would be a good practice to run the system for an hour a month”

    I used to run our little genny on a regular basis, but have been rather lax of late. When I attempted to start it last month it didn’t want to know. The “fuel” smelt more like paraffin than petrol, and even after adding some fresh unleaded it still wouldn’t run properly. I had to remove the tank and not only drain out the remains, but use a long brush and some solvent to remove a layer of gunge from the bottom. Fortunately an easy task with a 3hp Briggs & Stratton. After that it started first pull, and I’ve now drained the tank completely. If it doesn’t get used this winter the cans will be emptied into my car, and fresh fuel bought.

    As I’ve posted in comments at Bishop Hill, for short duration outages batteries and inverters can keep a few basics running – power for the gas central heating is the most important for us.

  4. Yes, I was referring to the generator. Switches then need to comply with both loads. The SDMO Switch I mentioned will handle 40amp generator(230v) and 100amp utility supply. Possibly an AVR (automatic voltage regulator) would be a desired option.

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