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

On Fri, 17 Sep 2004 19:20:49 +0000 (UTC), "GB"
wrote:

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?

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.


Does a standard consumer unit isolate both the live and the neutral?

Yes, but this is not relevant.



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?

Yes it does.


What does a cheap 500w generator do when someone turns on a 3 kw fire
upstairs by mistake?

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



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

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

Andy Hall wrote:

Sounds too simple, so what's wrong with that?


a) It's illegal

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.


b) It's highly dangerous for all concerned

No argument there...


--
Grunff

On Fri, 17 Sep 2004 21:57:39 +0100, Grunff wrote:

Andy Hall wrote:

Sounds too simple, so what's wrong with that?


a) It's illegal

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.

On at least two counts.

Part VI of the Electricity Safety, Quality and Continuity Regulations
2002

http://www.legislation.hmso.gov.uk/s...0022665.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-re...ns/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.






b) It's highly dangerous for all concerned

No argument there...

..andy

To email, substitute .nospam with .gl

Andy Hall wrote:

a) It's illegal

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.


On at least two counts.

snip documentary proof

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


--
Grunff

"Andy Hall" wrote in message
...



What does a cheap 500w generator do when someone turns on a 3 kw fire
upstairs by mistake?

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


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.

GB wrote:

"Andy Hall" wrote in message
...



What does a cheap 500w generator do when someone turns on a 3 kw fire
upstairs by mistake?

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



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.



Or possibly stall the motor, depending.

"GB" wrote in message
...

"Andy Hall" wrote in message
...



What does a cheap 500w generator do when someone turns on a 3 kw fire
upstairs by mistake?

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


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.

Not on a cheap likely chinese 500w unit no.

Tim..

"Andy Hall" wrote in message
...
On Fri, 17 Sep 2004 19:20:49 +0000 (UTC), "GB"
wrote:



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.

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
a

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

"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 a
| 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

"Owain" wrote in message
...



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


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.

On Sat, 18 Sep 2004 14:07:30 +0100, "GB"
wrote:


"Owain" wrote in message
...



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


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.


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

To email, substitute .nospam with .gl

Owain wrote:

"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 a
| 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.
I thought they normally shunted the circury in fault fxing?


Owain

In article , The Natural
Philosopher writes
Owain wrote:

"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 a
| 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.
I thought they normally shunted the circury in fault fxing?

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

GB wrote:
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.
snip
What does a cheap 500w generator do when someone turns on a 3 kw fire
upstairs by mistake?

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.

"Ian Stirling" wrote in message


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.

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.


--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

"Michael Mcneil" wrote in message
news:236805a5ceb67827d147a092a95a6713.45219@mygate .mailgate.org...


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?

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?



Just "up" your insurance cover.


I am more concerned about freezing to death.

"GB" wrote in message
...

"Michael Mcneil" wrote in message
news:236805a5ceb67827d147a092a95a6713.45219@mygate .mailgate.org...


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?

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?


You'll probably find that the freezer wont start with a 500w max generator
suppling it- the compressor is almost a dead short when stationary.

Tim..

On Sun, 19 Sep 2004 15:59:00 +0000 (UTC), Tim \(Remove NOSPAM. wrote:

You'll probably find that the freezer wont start with a 500w max
generator suppling it- the compressor is almost a dead short when
stationary.

As a rule of thumb a motor needs about 2 to 3 times it's running
rating to start. 500/3 = 160W, close but higher than most normal
freezers so it'll probably be OK provided there isn't much else on at
the same time.

Just looked at the fridge/freezer (140W) ordinary fridge (110W) and
upright freezer (90W).

--
Cheers
Dave. pam is missing e-mail

In an earlier contribution to this discussion,
GB wrote:

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

From the subsequent discussion, you're now well aware of the dangers of
doing it in the way originally suggested.

One point which I don't think has been made (forgive me if I have missed it)
is that of voltage stability and waveform. It seems to me a distinct
possibility that a cheap generator will produce all sorts of voltage
variations and spikes as loads are added or removed. If this is so, any
sensitive electronic equipment being powered by the genny - and I include
things like the control PCB in a central heating boiler in this category -
could be damaged, somewhat defeating the object of the exercise.

At the start of last winter, I bought a Honda generator (somewhat more
expensive than the ones discussed here!) as a precaution against power
outages. This actually generates DC, and produces "mains" - with a
(claimed!) very high degree of voltage stability - by means on an inverter.
It also has a 4-stroke engine and fairly good silencing - so the idea is
that it shouldn't annoy the neighbours too much if it is running for a few
hours - and might *even* be useful for caravanning in remote locations.

I do not intend to connect the genny to the house mains - but rather to
unplug certain items from the mains and plug them into the genny instead. In
order to facilitate this, I have modified the power supply to the central
heating - which is now fed from a 13A plug in the utility room rather than
from an FCU in the airing cupboard. My genny can produce about 1600 watts -
which should be sufficient for the heating controls, a couple of freezers, a
TV and a few lights - and even a microwave oven if most of the other load is
temporarily removed.

I have also sunk an earth spike in the garden, to which the genny's earth
lead will be attached.

I had no need to use it last winter - but it's a peace of mind thing. I
guess that I had ought to run it every now and then, to make sure it still
works!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Set Square wrote:

In an earlier contribution to this discussion,
GB wrote:


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


From the subsequent discussion, you're now well aware of the dangers of
doing it in the way originally suggested.

One point which I don't think has been made (forgive me if I have missed it)
is that of voltage stability and waveform. It seems to me a distinct
possibility that a cheap generator will produce all sorts of voltage
variations and spikes as loads are added or removed. If this is so, any
sensitive electronic equipment being powered by the genny - and I include
things like the control PCB in a central heating boiler in this category -
could be damaged, somewhat defeating the object of the exercise.

No. Not really. They all have regulated internal supplies.


At the start of last winter, I bought a Honda generator (somewhat more
expensive than the ones discussed here!) as a precaution against power
outages. This actually generates DC, and produces "mains" - with a
(claimed!) very high degree of voltage stability - by means on an inverter.
It also has a 4-stroke engine and fairly good silencing - so the idea is
that it shouldn't annoy the neighbours too much if it is running for a few
hours - and might *even* be useful for caravanning in remote locations.

I do not intend to connect the genny to the house mains - but rather to
unplug certain items from the mains and plug them into the genny instead. In
order to facilitate this, I have modified the power supply to the central
heating - which is now fed from a 13A plug in the utility room rather than
from an FCU in the airing cupboard. My genny can produce about 1600 watts -
which should be sufficient for the heating controls, a couple of freezers, a
TV and a few lights - and even a microwave oven if most of the other load is
temporarily removed.

The esy way to do this is to simply find way of feeding the genny to
the CU busbars via its own mains switch and even RCD, and then deselect
incoming mains, and as many house circuts as are not immediately required.


I have also sunk an earth spike in the garden, to which the genny's earth
lead will be attached.

I had no need to use it last winter - but it's a peace of mind thing. I
guess that I had ought to run it every now and then, to make sure it still
works!

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
GB wrote:

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

From the subsequent discussion, you're now well aware of the dangers of
doing it in the way originally suggested.

One point which I don't think has been made (forgive me if I have missed
it)
is that of voltage stability and waveform. It seems to me a distinct
possibility that a cheap generator will produce all sorts of voltage
variations and spikes as loads are added or removed. If this is so, any
sensitive electronic equipment being powered by the genny - and I include
things like the control PCB in a central heating boiler in this category -
could be damaged, somewhat defeating the object of the exercise.

At the start of last winter, I bought a Honda generator (somewhat more
expensive than the ones discussed here!) as a precaution against power
outages. This actually generates DC, and produces "mains" - with a
(claimed!) very high degree of voltage stability - by means on an
inverter.
It also has a 4-stroke engine and fairly good silencing - so the idea is
that it shouldn't annoy the neighbours too much if it is running for a few
hours - and might *even* be useful for caravanning in remote locations.

I do not intend to connect the genny to the house mains - but rather to
unplug certain items from the mains and plug them into the genny instead.
In
order to facilitate this, I have modified the power supply to the central
heating - which is now fed from a 13A plug in the utility room rather than
from an FCU in the airing cupboard. My genny can produce about 1600
watts -
which should be sufficient for the heating controls, a couple of freezers,
a
TV and a few lights - and even a microwave oven if most of the other load
is
temporarily removed.

I have also sunk an earth spike in the garden, to which the genny's earth
lead will be attached.


I believe, depending on which supply system your house is supplied with (TT,
PME, TC-S etc etc) that when running with a conventional generator through
a change over switch etc, that you should have the neutral and earth
connections at the generator bonded together and an earth spike.

Thus the neutral is referenced to 0 potential and not floating at 115v as it
would be without this. If a fault to earth occured you could well get a 115v
shock if this isnt the case.

With a 240v inverter type generator, am not sure if the above should apply.
Probably not...

Tim..

On Sun, 19 Sep 2004 16:04:39 +0000 (UTC), Tim \(Remove NOSPAM. wrote:

I believe, depending on which supply system your house is supplied
with (TT, PME, TC-S etc etc) that when running with a conventional
generator through a change over switch etc, that you should have the
neutral and earth connections at the generator bonded together and
an earth spike.

You *must* bond one of the generator phases(*) to the chassis and to a
properly installed earth spike with suitably rated cable. This earth
also needs to be connected to the installations earth again via
suitably rated cable. I'd also feed the generator in via an RCD.

What you do with this local earth and the supply earth when running
from the generator is the problem and does depend on the type of you
have. With PME, ie the supply earth is locally derived and neutral is
bonded to it at the supply point then I think it's pretty safe just to
tie them all together and not worry about it. Where the supply earth
comes in as a seperate wire or connection I'm not so sure about. You
cannot relie on the supply earth under fault conditions (power cuts =
faults, who knows what the enginneers will do to fix the fault).

Thus the neutral is referenced to 0 potential and not floating at
115v as it would be without this. If a fault to earth occured you
could well get a 115v shock if this isnt the case.

You'd more likely get the full output of the generator, the fault
would pull that phase down to earth, if you picked up the other phase,
ouch.

With a 240v inverter type generator, am not sure if the above should
apply. Probably not...

No one phase still needs to be designated "neutral" and bonded to
local earth.

(*) The alternator generates two phases 180 degrees apart, until you
designate one "neutral" and bond it to local and installation earth
you have the potential for all manner of weirdness with the
installations live and neutrals being anywhere from 0 to 230v with
respect to earth.

--
Cheers
Dave. pam is missing e-mail