Power Cuts/Generators yet again

[Set Square]

With the likely prospect of the National Grid not coping if we get a cold spell, I am looking seriously at providing a simple means of powering the electrical bits (boiler control/pump/3-port valve) of my gas central heating system, plus a couple a freezers and a few lights.

I'm not looking at permanently installed gen sets - and certainly not automatic changeover etc. I'm considering a small portable generator (maybe Honda eu10i or eu20i) powering a 6-way extension lead into which I would plug the relevant devices, having unplugged them from the mains. [The central heating is currently hard-wird into a fused spur - but it would be trivial to change that for a 13A plug/socket (with a 3A fuse, of course)].

The generators I am looking at use inverter technology to produce a (allegedly) sinusoidal output, and control the output voltage to 2 or 3%.

I have a couple of concerns/questions on which I would value your input.

Firstly, are there any compelling reasons why it would be a *bad* thing to do what I suggest?

Secondly, what earthing arrangements would I need to make? [The central heating pipes are bonded to the electricity board's earth and to a metal gas pipe which disappears underground].

Thirdly, how sensitive are boiler PCBs to spikes etc. on the mains? Although the mains voltage would be controlled in a steady state condition, I envisage that there may be spikes when the load changes - such as when freezers go on or off on their stats. The boiler, incidentally, is a Baxi Solo 70/4 PF (MkI). If this *is* a potential problem, would it help to use an anti-surge device such as those sold for use with computers?

TIA.

[Paul W]

One of the easiest ways to distribute your generator power is to "back feed" it into a ring main.

First of all, once the power goes off, switch OFF the isolator in the CU, then switch off all the breakers.

Make up a very dangerous lead with the generator connected to one end and a

3 pin plug on the other, then plug this into a socket on your ring main. This will back feed the whole ring main, so ensure only the devices you want to run (taking into account the power of the generator) are switched on.

If you are careful, you can then switch on the breaker of that ring main, together with the breakers of any other circuits you want to "back feed". (NOTE DO NOT TURN ON THE MAIN ISOLATOR).

The main advantage of doing it this way is that all the earthing is already taken care of, and you don't have miles of cables running all over the house.

You may have to be careful if you have a split load CU with and RCD, you may not be able to "back feed" across the RCD into the non RCD protected side (e.g. lights) without upsetting the RCD.

Oh and when the power comes back on, make sure you remove the generator before turning the mains back on !

Cheers,

Paul.

[Pete Cross]

"One of the easiest ways to distribute your generator power is to "back feed" it into a ring main."

Isn't that a bit dodgy ? if someone half reads your posting and fails to absorb the bit about turning off the isolator then you run the risk of electrocuting some poor sod at the sub-station fixing your power line.

[Wanderer]

To Paul W I would say please go right ahead and do it, as a matter of some urgency. It might help remove some defective genes from the human gene pool.

To anyone else - DO NOT DO IT! That is some of the worst advice I have ever seen.

[Andrew Gabriel]

Yes, very. In my view, this would be sufficient grounds for a supplier to immediately disconnect your electricity supply. The HSE could also go on to prosecute you.

Exactly. Implementing any type of transfer switch mechanism which is not foolproof against backfeeding would be extreemly dangerous, and should see you instantly disconnected from the electricity supply if the supply authority finds out.

Also the comment about the earthing being take care of is not true. You are not allowed to assume a supplier's provided earth connection is still working when the supply isn't working.

[Paul W]

As long you are carefull, this is still the safest and easiest way of powering household appliances during a power cut as everything is well earthed.

It is only bad advice if not followed correctly.

Paul.

[Paul W]

I think your generator would go bang well before that happened as it would be trying to supply power to everyone else in the street on the same phase.

I guess I should have added a note that this should only be attempted by a competant person, who actually understands a bit about electricity.

Paul.

[Paul W]

I have done this MANY times, both at home and at work, and as long as you are carefull and understand what you are doing, it is perfectly safe.

Paul.

[Andrew Gabriel]

It's incredibly bad and dangerous advice, and if your supplier finds out, you'll have your supply disconnected. See my other posting.

[usenet]

Nothing is "perfectly safe" and this way of connecting a generator seems to me to be quite a long way from "perfectly safe", especially in a household with (probably) more than one person around the place.

[Paul W]

OK, so if you don't open the Isolator there is a risk, and if you start the generator before plugging in the live plug there is a risk, BUT if you are carefull and do both of these bits properly, what else is not safe ?

Paul.

[Harry Bloomfield]

On 08/01/2004 Paul W opined:-

All very dangerous advice as well as highly illegal and you might well find yourself in court on a manslaughter charge.

[Harry Bloomfield]

Paul W wrote on 08/01/2004 :-

Supposing a member of your family, or a workmate etc closed the isolator, then you would be backfeeding down the mains.

Supposing a member of your family, or a workmate uplugged the generator from the wall socket with it running, the plug end would be live.

Both are very good reasons why doing such is highly illegal and no doubt if caught you would be liable to have your supply cut off and H&S would without doubt have you in court.

[Paul W]

Surely the only way this can be illegal is because there is not a fool proof method of disonnecting the house from the grid ?

Paul.

[Paul W]

OK, althought I have done this a few times under controlled conditions, I agree I shouldn't have advised anyone to do this, as if you are not carefull there are some risks associated with my suggestions.

Regards,

Paul.

[Set Square]

Thankyou Andrew. I have no intention of feeding the generator into a ring main - and certainly won't follow the advice of the initial respondent!

As per my original post, I indend to unplug selected "devices" (including the CH) from the ring main and plug them into the generator instead.

I still need some advice please with respect to earthing - and spike protection, if necessary, for the boiler electronics.

[Paul W]

OK, althought I have done this a few times under controlled conditions, I agree I shouldn't have advised anyone to do this, as if you are not carefull there are some risks associated with my suggestions.

Regards,

Paul.

[PoP]

You've done this at work? Could you please advise us all where you work? I'd like to make sure that none of my family goes near the place.

PoP

If you really must use the email address provided with my newsreader please be aware that the email is processed with spamcop. As a result your email to me might be treated as spam!

[Tim Jenkins]

Does anyone have any advice on SS's Earthing/Filtering question - I'm curious what the answer is too :-)

Tim.

[Dave Plowman]

Having the possibility of any sort of plug live with lethal voltages is just not on. You may think you know how to use it safely - but it will be lying around when not in use and others in the household may not.

If you can afford a generator, you can afford to connect it correctly - one suitable for running the entire house as you suggest won't be cheap.