Generator

[GB]

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

[Andy Hall]

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

To email, substitute .nospam with .gl

[Steve Firth]

Aaaarrrrrrgghhhhhhhh.

This is a troll, right?

[Grunff]

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...

[Andy Hall]

On at least two counts.

Part VI of the Electricity Safety, Quality and Continuity Regulations

2002

quote:

****** Switched alternative sources of energy

1. 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

1. - (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.

********

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

To email, substitute .nospam with .gl

[Grunff]

Oops, guess it is illegal. No beer for me this weekend.

[GB]

No, I am *not* a troll, or at least not meaning to be one. I actually have a degree in physics, and using that bit of knowledge it seems quite a straightforward connection job. I obviously have no idea about the electrical safety regs., but I can see there is a benefit to having something which is a bit more foolproof than my initial thoughts.

.andy suggested as follows:

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

I take it that this is a device that isolates your house from the mains and switches over to the generator at the same time? You permanently connect the generator to this, so all you have to do is flip the switch and start the generator?

[GB]

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.

[Grunff]

That's it - a changeover switch rated at whatever you incomin mains current max is - 100A or so.

[Ian Stirling]

Probably stalls. If someone plugs in a 800W load, it'll probably have a thermal cutout activate in a minute or two.

Quality varies. My sub-100 pound generator (ebay) works fine, starts reliably, and has about

8 leaks round the edge of the fuel tank. Dip tube into a plastic tank fixed that.

The rightest way to do this is a transfer switch rated for the full load of the CU, as others have said.

I'd be tempted to do it a bit differently. Disconnect lighting circuit at CU, and attach boiler to this circuit. Add several 1-2A round-pin sockets to this circuit too. (ensuring that it's properly able to cope with the load.)

Now, attach lighting circuit to UPS. Attach other side of UPS to double pole changeover switch, one of which goes to the CU, the other to the generator. The UPS will drastically reduce the number of times you need to start the generator, reducing wear-and-tear on it, as well as noise.

[GB]

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

[Andy Hall]

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

To email, substitute .nospam with .gl

[Steve Firth]

Oh right, that would explain the decision to make the most dangerous electrical connection possible then. the only person I knew who managed to electrocute themselves (fatally) was a physicist.

There's IMM around this group somewhere. You and he could get together and discuss your respective degrees sometime.

[Michael Mcneil]

Noise and fuel consumtion will be the big problems with a cheap machine. What sort of natural phenomenon are you expecting?

If it's going to be electical producers on strike, you may be on a winner but anything else is not likely to last more than a day or so is it?

Just "up" your insurance cover.

[GB]

I remember going to a practical physics seminar given by the head of the Rutherford Laboratory. I was somewhat mortified when he quoted from my entrance exam paper as an example of how not to do a particular experiment. I don't think he did it specially for my benefit, so I guess he had turned my exam answer into a sort of party piece, complete with dramatic gestures when it came to the bit about the building blowing up.

Geoff

[GB]

I was mostly concerned about the odd strike now and again. Very very occasional events like that, so I'm not fussed if the system involves a bit of scurrying around plugging and unplugging things. As it is for very occasional use only, I am more concerned to keep the cost down. If I have to refill the generator every couple of hours, well I guess I will put up with that.

The trouble is that *everything* works off electricity these days. I don't think the gas hob will light without an electricity supply because of the flame-out device, for example. Certainly, the central heating stops.

I think .andy's suggestion of just running an extension lead from the generator and plugging in the freezer and central heating should do it. If there is a bit of power to spare, we can plug in a table lamp or two, as well. I'm not sure how much power the freezer takes when the motor starts up?

I am more concerned about freezing to death.

[The Natural Philosopher]

Or possibly stall the motor, depending.

[mike ring]

[e-mail] (Steve Firth) wrote in news:[e-mail]:

That's a bit off.

GB had an idea, ran it past us, the knowledgeable said it wouldn't do, and why.

What's wrong with that process? It may even have saved lives (all right, that's a bit far-fetched, but a *real* possibility).

GB even knows when he's straying outside his expertise, and seeks advice.

Do you?

And as for the possibly apocryphal anecdote

"Who cyclee best most often fallee-down, Who swimee best, it's him most often dlown"

mike

[John]

That's the idea. MEM used to make a range of them back in the sixties IIRC as 15, 30, 45, 60Amp rating. No doubt the same sort of thing is still available. I installed a geny when the winter of discontent was on, to power a warehouse lighting from a single phase diesel generator during power cuts. This involved a three pole and neutral changeover metalclad switch and was connected in a sub main between the main power board and a lighting sub board. (Oh and of course there was a 13 amp socket off this sub board to boil the kettle during tea breaks ). The spare switch poles were used to automatically connect a red lamp and buzzer to the mains supplied incoming circuit so the workforce knew when the power had come back on again. Switching back disconnected this lamp and buzzer. Prior to this installation the workforce had indeed tried to drive the town from their puny little generator with instantaneous attendant ill effects to the generator, fortunately not the town or its inhabitants.

[Owain]

"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