Generator

I've just been looking at some really cheap generators for emergency use. I was thinking about one of the sub-100 Pound jobbies. I just want a light or two plus enough power to run the gas central heating system in case there is a power cut.
I was wondering about wiring this up. I deally, what I would like to do is simply run up a lead with a standard plug at each end.
Then, in the event of a power outage: 1. Switch off the mains supply, hopefully isolating the house from the national grid (as I really can't hope to power the whole country from my little genny). 2. Switch off everything in the house apart from the central heating. 3. Plug cable into both the genny and one of the 13 amp power sockets around the house. 4. Start genny.
Sounds too simple, so what's wrong with that?
Does a standard consumer unit isolate both the live and the neutral?
There's a *really big* switch in a box in the garage - large grey box with a sort of door handle on the front. Is that likely to isolate both? Should I just open it up and have a look?
Does it matter if you don't isolate the neutral? Isn't that at earth voltage anyway?
What does a cheap 500w generator do when someone turns on a 3 kw fire upstairs by mistake?
Any help most gratefully received. BTW I did google for this, but I could not find a reply to the question I put. Perhaps it's obvious that it won't work, then?
Regards
Geoff
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On Fri, 17 Sep 2004 19:20:49 +0000 (UTC), "GB"

a) It's illegal
b) It's highly dangerous for all concerned
One moment of aberration with plugs and switches, which is easy in the dark and you run the risk of electrocutiing yourself or possibly some unfortunate engineer working on restoring the supply.
Don;t even think about doing this.

Yes, but this is not relevant.

Yes it does.

Trip a breaker, blow a fuse or burn out the generator.

The only way to do this safely is with the correct type of switchover isolator specifically meant for the job.
.andy
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Andy Hall wrote:

Not wanting to encourage the OP, but is it really illegal? If so, which aspect? I must own up to having done just this on one occasion when caught short.

No argument there...
--
Grunff

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On at least two counts.
Part VI of the Electricity Safety, Quality and Continuity Regulations 2002
http://www.legislation.hmso.gov.uk/si/si2002/20022665.htm#21
To quote:
****** Switched alternative sources of energy
21. Where a person operates a source of energy as a switched alternative to a distributor's network, he shall ensure that that source of energy cannot operate in parallel with that network and where the source of energy is part of a low voltage consumer's installation, that installation shall comply with British Standard Requirements.
Parallel operation
22. - (1) Without prejudice to regulation 21, no person shall install or operate a source of energy which may be connected in parallel with a distributor's network unless he -
(a) has the necessary and appropriate equipment to prevent danger or interference with that network or with the supply to consumers so far as is reasonably practicable;
(b) has the necessary and appropriate personnel and procedures to prevent danger so far as is reasonably practicable;
(c) where the source of energy is part of a low voltage consumer's installation, complies with British Standard Requirements; and
(d) agrees specific requirements with the distributor who owns or operates the network.
(2) Sub-paragraphs (b) and (d) of paragraph (1) shall not apply to a person who installs or operates a source of energy which may be connected in parallel with a distributor's network provided that sub-paragraphs (a) and (c) of paragraph (1) are complied with; and
(a) the source of energy does not produce an electrical output exceeding 16 amperes per phase at low voltage;
(b) the source of energy is configured to disconnect itself electrically from the parallel connection when the distributor's equipment disconnects the supply of electricity to the person's installation; and
(c) the person installing the source of energy ensures that the distributor is advised of the intention to use the source of energy in parallel with the network before, or at the time of, commissioning the source.
********
http://www.dti.gov.uk/electricity-regulations/gfesqcr.pdf
Without the proper switchgear, prevention of parallel operation cannot be guaranteed.
Secondly under the Electricty Acts, a license is required to generate electricity for supply to the grid, although there appear to be specific exemptions for local wind etc. generators with appropriate switchgear.
However, I think that the 2002 Act covers it.
Plus, if one were to do this, put power into the network and kill someone, it might be a touch tricky defending a charge of manslaughter as well.

.andy
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Andy Hall wrote:

<snip documentary proof>
Oops, guess it is illegal. No beer for me this weekend.
--
Grunff

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That does seem to cover all the possibilities that I thought of before asking the question. I thought there might be a standard that these generators are usually built to. Thanks for confirming in a slightly roundabout way that there isn't.
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GB wrote:

Or possibly stall the motor, depending.
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Not on a cheap likely chinese 500w unit no.
Tim..
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wrote:>

Giving this some more thought, I fully accept what you said. There's too many things that have to be done right. As I see it, the main safety issues are:
a) The connecting cable could potentially have live pins exposed b) Relies on nobody turning the main switch back on again c) Relies on the main switch working
Make a mistake with b or c and you could really hurt some poor contractor working in the rain to restore power. (In practice, this is only a problem if a small part of the supply has been isolated, so you would probably get away with the error, but I agree that's not the point.)
That's enough to be going on with, along with it being illegal, or have I missed something important?
Thanks for being patient with me.
Regards
Geoff
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"GB" wrote | Giving this some more thought, I fully accept what you said. There's | too many things that have to be done right. As I see it, the main | safety issues are: | a) The connecting cable could potentially have live pins exposed | b) Relies on nobody turning the main switch back on again | c) Relies on the main switch working | Make a mistake with b or c and you could really hurt some poor | contractor working in the rain to restore power. (In practice, | this is only a problem if a small part of the supply has been | isolated, so you would probably get away with the error, but | I agree that's not the point.)
Bear in mind that although your generator would be putting out 240V, it could be backfeeding a transformer where an electrician working on the isolated supply-side terminals would be rather startled to suddenly find kilovolts appearing.
Owain
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I take the point that it's unsafe, but isn't this scenario very unlikely indeed? Surely it could only happen if every other house apart from mine is isolated from the path to the transformer? If the other houses in the street are still connected up, then the load on the generator will cause it to stop, burn out, or whatever.
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wrote:

Normally three phases are run from the substation to the local area, so in practice only every third house is connected to a give phase.
.andy
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Owain wrote:

I thought they normally shunted the circury in fault fxing?

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The times I've seen them at work on overhead plant is that they short all three phases together and then connect that to an earth stake and only remove it when the work is done and the line is to be re-energised.
Rather sensible and I suppose a practice born out of past adverse experiences.
--
Tony Sayer


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On Sun, 19 Sep 2004 15:06:24 +0100, tony sayer wrote:

You've missed out the long handled volt stick they wave about before they attach the earthing bonds via long handled insulated tools.
I'm not totaly convinced that such bonding would protect from back feeding from a portable generator connected by the highly dangerous double plug method. The load presented may well make the genny struggle and possibly trip/stall but if there wasn't much load where is the circuit via earth?
There is no decent connection from either phase of the generator to earth unless you deliberatly install an earth spike and bond that to one of the generator phases. Granted one phase might be connected to the generator chassis and that might be resting on the ground and might be making a good low impedance connection but thats rather a lot of "mights". Remember there is no RCD the only disconnection device is the overload trip.
--
Cheers snipped-for-privacy@howhill.com
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<snip> Wouldn't a generallised safe solution be to plug a RCD into the generator, to have an earthing spike going from the chassis/local earth to ground, and plug the load into the RCD?
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Which way round is that and what's it going to protect?...
--
Tony Sayer


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The RCD plugged into the generators socket, and feeding the rest of the house.
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On 19 Sep 2004 23:07:05 GMT, Ian Stirling wrote:

Yes but it's not fail safe, it relies on the RCD being plugged in and not removed if/when it "nuisance" trips. And you still need to bond one of the generator phases to chassis and local earth rod so that things are correct for the house wiring, ie "neutral" can't float significantly away from earth.
--
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wrote:

No problem. I just didn't want to see you hurt yourself. You've highlighted the risks exactly
What you could do, and would be a reasonable solution if you wanted something simpler would be:
a) Put in some additional wiring and outlet sockets at critical places like CH, Freezer etc. You'd need a plug/socket for the CH for this of course.
b) Wire these to the generator and in the event of a power cut, you move the appliance plugs over to the emergency circuit. You still have to be sensible about not overloading the generator, but there would be no risk of powering the mains.
c) Put in some emergency lights in strategic places. The 8w maintained fluorescent type are quite inexpensive and reasonable for this. You can switch them on and off if you want use as a normal light but then they come on when the power fails. I put one in the cupboard where my consumer unit is for example.
.andy
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