As we live in a remote country area and suffer the occasional
power-cut, we are toying with the idea of getting a portable generator
to power the essentials at such times, especially as the predictions
going around ATM don't inspire confidence for the future. The one
we're thinking about is the Wolf 230V/2000W model (I assume AC), from
Screwfix. Probably not cost-effective, but at least it'll keep the gas
c/h, TV, lighting and freezers going. But before we splash out, I have
some questions.

We have a TT system with a 100A/100mA time delayed RCD at the 'front
end', and a split-load CU with MCB's and a 30mA RCD on one half. Is it
acceptable simply to run a cable from the generator to any socket in
the house on one of the ring mains for example, to in effect power the
whole house? Presumably the front-end RCD would need to be switched
off before connecting the generator, both to avoid powering the
neighbourhood (!) and to avoid nasty things happening when the mains
power comes back on. Or do I have to power items individually and
directly, independent of the house wiring, using a network of
extension leads?

If it's acceptable to connect the generator that way, the MCB on the
ring connected to the generator would be powered 'backwards' as it
were, IYSWIM, but the remaining MCB's would still be in 'forward'
mode. Is this OK?

Do RCD's work 'backwards' ? (The power from the house lights would run
from the RCD side back through the RCD to the lighting MCB).

I assume it's a good idea to isolate the high-power items such as the
cooker and the immersion heater, to avoid accidental use and overload
of the generator, although an appropriate fuse in the linking cable
from the generator would probably do just as well.

What happens to the earthing arrangements when using a portable
generator in this way? As I said, we have a TT system with local earth
rods. Do I have to rig up some sort of earth for the generator, or do
I just ignore it, running the system as what I believe is called on
the FAQ an IT system? Do the terms 'live' and 'neutral' have any
significance when using such a generator?

Is there anything that it's best not to power from a generator, such
as a computer or other electronic equipment (but what hasn't got
electronic circuits in it these days?), or fluorescent lights?


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net

"Chris Hogg" wrote in message
...
As we live in a remote country area and suffer the occasional
power-cut, we are toying with the idea of getting a portable generator
to power the essentials at such times, especially as the predictions
going around ATM don't inspire confidence for the future. The one
we're thinking about is the Wolf 230V/2000W model (I assume AC), from
Screwfix. Probably not cost-effective, but at least it'll keep the gas
c/h, TV, lighting and freezers going. But before we splash out, I have
some questions.

We have a TT system with a 100A/100mA time delayed RCD at the 'front
end', and a split-load CU with MCB's and a 30mA RCD on one half. Is it
acceptable simply to run a cable from the generator to any socket in
the house on one of the ring mains for example, to in effect power the
whole house? Presumably the front-end RCD would need to be switched
off before connecting the generator, both to avoid powering the
neighbourhood (!) and to avoid nasty things happening when the mains
power comes back on. Or do I have to power items individually and
directly, independent of the house wiring, using a network of
extension leads?

If it's acceptable to connect the generator that way, the MCB on the
ring connected to the generator would be powered 'backwards' as it
were, IYSWIM, but the remaining MCB's would still be in 'forward'
mode. Is this OK?

Do RCD's work 'backwards' ? (The power from the house lights would run
from the RCD side back through the RCD to the lighting MCB).

I assume it's a good idea to isolate the high-power items such as the
cooker and the immersion heater, to avoid accidental use and overload
of the generator, although an appropriate fuse in the linking cable
from the generator would probably do just as well.

What happens to the earthing arrangements when using a portable
generator in this way? As I said, we have a TT system with local earth
rods. Do I have to rig up some sort of earth for the generator, or do
I just ignore it, running the system as what I believe is called on
the FAQ an IT system? Do the terms 'live' and 'neutral' have any
significance when using such a generator?

Is there anything that it's best not to power from a generator, such
as a computer or other electronic equipment (but what hasn't got
electronic circuits in it these days?), or fluorescent lights?


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]ne

C/H tv lighting and freezers from 2000w, ?
U sure?

Annette Kurten wrote:

C/H
Pump + boiler = 200W


tv
100W


lighting
Really depends. Our house, with CFs all round = 200W with all lights on.


freezers
200W/freezer


from 2000w, ?

With bags to spare.


--
Grunff

On Wed, 10 Mar 2004 18:04:16 +0000, in uk.d-i-y Chris Hogg
strung together this:

We have a TT system with a 100A/100mA time delayed RCD at the 'front
end', and a split-load CU with MCB's and a 30mA RCD on one half. Is it
acceptable simply to run a cable from the generator to any socket in
the house on one of the ring mains for example, to in effect power the
whole house? Presumably the front-end RCD would need to be switched
off before connecting the generator, both to avoid powering the
neighbourhood (!) and to avoid nasty things happening when the mains
power comes back on.

Seriously dangerous. Do not under any circdumstances ever think about
doing anything like this ever again.

Or do I have to power items individually and
directly, independent of the house wiring, using a network of
extension leads?

That's one way, depends how often and how much convenience you want
from the system.

I assume it's a good idea to isolate the high-power items such as the
cooker and the immersion heater, to avoid accidental use and overload
of the generator, although an appropriate fuse in the linking cable
from the generator would probably do just as well.

Yes to the isolation of high power equipment, the onboard cutout on
the generator should do the overload protection.

What happens to the earthing arrangements when using a portable
generator in this way? As I said, we have a TT system with local earth
rods. Do I have to rig up some sort of earth for the generator, or do
I just ignore it, running the system as what I believe is called on
the FAQ an IT system? Do the terms 'live' and 'neutral' have any
significance when using such a generator?

See the thread here;
http://tinyurl.com/2ywon
It goes a bit wayward at the end but it's basically the same question
as yours.

Is there anything that it's best not to power from a generator, such
as a computer or other electronic equipment (but what hasn't got
electronic circuits in it these days?), or fluorescent lights?

Debatable, I've done it in the past but for long term or frequent use
I would probably put some sort of filter\mains conditioning on the
line to electronics. A UPS would be a good idea.
--

SJW
A.C.S. Ltd.

On Wed, 10 Mar 2004 19:58:58 GMT, (Lurch)
wrote:
See the thread here;
http://tinyurl.com/2ywon
It goes a bit wayward at the end but it's basically the same question
as yours.


Thanks Lurch. That thread has it all.


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net

Chris Hogg laid this down on his screen :
We have a TT system with a 100A/100mA time delayed RCD at the 'front
end', and a split-load CU with MCB's and a 30mA RCD on one half. Is it
acceptable simply to run a cable from the generator to any socket in
the house on one of the ring mains for example, to in effect power the
whole house? Presumably the front-end RCD would need to be switched
off before connecting the generator, both to avoid powering the
neighbourhood (!) and to avoid nasty things happening when the mains
power comes back on. Or do I have to power items individually and
directly, independent of the house wiring, using a network of
extension leads?

I hope the idea of back feeding your system via a socket was just a
passing thought?

It would be highly dangerous to both you and anyone who happened to be
working to repair your failed supply. I caught doing this you would
certainly end up with a term in prison and perhaps even a man slaughter
charge. PLEASE DO NOT CONSIDER IT FURTHER!

Using extensions and plugging table lights, TV's and freezers into
those is acceptable.

If you want to keep a computer going, consider a UPS. A UPS would work
fine on a generator.

If you really must power your existing wiring from both mains and a
generator, then there are specially made isolator/switch systems made
for the purpose.

--


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org

On Wed, 10 Mar 2004 18:34:08 +0000 (UTC), Annette Kurten wrote:

C/H tv lighting and freezers from 2000w, ?
U sure?

Easy, we cook by 'letric, have rather to many incandesant lights
rather than CFLs (6 of which account for 4 units/day, see other post
about SES CFLs...) and 3 computers running 24/7 with another 1 for at
least 18hrs day. 1 normal fridge, 1 large fridge freezer and 1
freezer.

We still average less than 24 units/day. So the mean load is less than
1000W. Obviously there are peaks when the cooking devices are in use,
or the washing machine heating water or the kettle but that power is
included in the average.

--
Cheers
Dave. pam is missing e-mail

On Wed, 10 Mar 2004 18:04:16 +0000, Chris Hogg wrote:

But before we splash out, I have some questions.

Wander over to groups.google.com and search in this group back 3 to 6
months and you'll find quite a thread or two. I think it covers all
your questions, if not come back and ask the specifics.

--
Cheers
Dave. pam is missing e-mail

Harry Bloomfield wrote:

It would be highly dangerous to both you and anyone who happened to be
working to repair your failed supply. I caught doing this you would
certainly end up with a term in prison and perhaps even a man slaughter
charge. PLEASE DO NOT CONSIDER IT FURTHER!

How exactly would it be dangerous if you have switched off your main
breaker (i.e. both live and neutral)?

--
Grunff

For one thing, powering a ring main via one of the plugs would mean that the
protection in the CU etc is bypassed, at least on the ring main where the
connection was made. Also, one could not simply use a normal plug to go into
the socket - the male terminals would be live when it was unplugged. I also
strongly suspect that a higher integrity isolation would be required from
the mains supply - supposing the power cut was made to isolate a circuit for
maintenance ... only to find it powered up from the generator. It is not a
safe system. No doubt more learned contributors would add more reasons.

"Grunff" wrote in message
...
Harry Bloomfield wrote:

It would be highly dangerous to both you and anyone who happened to be
working to repair your failed supply. I caught doing this you would
certainly end up with a term in prison and perhaps even a man slaughter
charge. PLEASE DO NOT CONSIDER IT FURTHER!

How exactly would it be dangerous if you have switched off your main
breaker (i.e. both live and neutral)?

--
Grunff

On Wed, 10 Mar 2004 22:12:02 +0000, in uk.d-i-y Grunff
strung together this:

Harry Bloomfield wrote:

It would be highly dangerous to both you and anyone who happened to be
working to repair your failed supply. I caught doing this you would
certainly end up with a term in prison and perhaps even a man slaughter
charge. PLEASE DO NOT CONSIDER IT FURTHER!

How exactly would it be dangerous if you have switched off your main
breaker (i.e. both live and neutral)?

If you have to ask you deserve to cast into the bowels of disastrous
diy deaths.
If you do it that way the electricity is not where it's meanto be and
there is also a standard 13A plug top waving around with 240V across
the pins. Don't argue with this one again. Look on the thread I
mentioned in my reply to this question.
--

SJW
A.C.S. Ltd.

Lurch wrote:

It would be highly dangerous to both you and anyone who happened to be
working to repair your failed supply. I caught doing this you would
certainly end up with a term in prison and perhaps even a man slaughter
charge. PLEASE DO NOT CONSIDER IT FURTHER!

How exactly would it be dangerous if you have switched off your main
breaker (i.e. both live and neutral)?


If you have to ask you deserve to cast into the bowels of disastrous
diy deaths.
If you do it that way the electricity is not where it's meanto be and
there is also a standard 13A plug top waving around with 240V across
the pins. Don't argue with this one again. Look on the thread I
mentioned in my reply to this question.


Read what Harry said, then read my reply.

I'm perfectly aware that you'd have a live plug, but my point is that it
would pose *no danger whatsoever* to someone working on the electricity
lines if you have isolated your CU from the incoming line.

It is by no means an ideal setup, and if you do it you have to be very
careful, but it does work fine. I have done this when I've needed to.

--
Grunff

Harry Ziman wrote:

For one thing, powering a ring main via one of the plugs would mean that the
protection in the CU etc is bypassed, at least on the ring main where the
connection was made. Also, one could not simply use a normal plug to go into
the socket - the male terminals would be live when it was unplugged. I also
strongly suspect that a higher integrity isolation would be required from
the mains supply - supposing the power cut was made to isolate a circuit for
maintenance ... only to find it powered up from the generator. It is not a
safe system. No doubt more learned contributors would add more reasons.

See my reply to Lurch.

--
Grunff

On Wed, 10 Mar 2004 22:42:23 +0000, in uk.d-i-y Grunff
strung together this:

Lurch wrote:

It would be highly dangerous to both you and anyone who happened to be
working to repair your failed supply. I caught doing this you would
certainly end up with a term in prison and perhaps even a man slaughter
charge. PLEASE DO NOT CONSIDER IT FURTHER!

How exactly would it be dangerous if you have switched off your main
breaker (i.e. both live and neutral)?


If you have to ask you deserve to cast into the bowels of disastrous
diy deaths.
If you do it that way the electricity is not where it's meanto be and
there is also a standard 13A plug top waving around with 240V across
the pins. Don't argue with this one again. Look on the thread I
mentioned in my reply to this question.


Read what Harry said, then read my reply.

I'm perfectly aware that you'd have a live plug, but my point is that it
would pose *no danger whatsoever* to someone working on the electricity
lines if you have isolated your CU from the incoming line.

It is by no means an ideal setup, and if you do it you have to be very
careful, but it does work fine. I have done this when I've needed to.

I could place an old copper water cylinder in the middle of my hallway
then connect it to the live terminal of the service cutout. If I don't
touch it does that make it safe? What's the difference between the two
scenarios? A lot of the questions asked on this group come from people
with little or no knowledge. Giving out stupid and downright dangerous
advice like that is absolutely ridiculous. I am at a total loss as to
why you even thought about posting an answer\response on here.
--

SJW
A.C.S. Ltd.

Lurch wrote:

I could place an old copper water cylinder in the middle of my hallway
then connect it to the live terminal of the service cutout. If I don't
touch it does that make it safe? What's the difference between the two
scenarios? A lot of the questions asked on this group come from people
with little or no knowledge. Giving out stupid and downright dangerous
advice like that is absolutely ridiculous. I am at a total loss as to
why you even thought about posting an answer\response on here.

I could say the same about the above response!

--
Grunff

"Chris Hogg" wrote in message
...
As we live in a remote country area and suffer the occasional
power-cut, we are toying with the idea of getting a portable generator
to power the essentials at such times, especially as the predictions
going around ATM don't inspire confidence for the future. The one
we're thinking about is the Wolf 230V/2000W model (I assume AC), from
Screwfix. Probably not cost-effective, but at least it'll keep the gas
c/h, TV, lighting and freezers going. But before we splash out, I have
some questions.

If you want to use your household wiring, you would need some sort of change
over switch so that you either connect to your generator or the normal power
supply.

The reason for this is that you are dealing with alternating current. If you
connected your generator to a live mains power supply it likely would not be
running in phase (and maybe at the wrong speed). This could lead to large
current flows and accompaning fireworks.

A change over switch would also help you avoid powering all your neighbours. The
main cable to your house would act like a very large load during a power cut.

Makes you wonder what the proposed Micro CHP systems will do when power is
restored after a cut.

Is there anything that it's best not to power from a generator, such
as a computer or other electronic equipment (but what hasn't got
electronic circuits in it these days?), or fluorescent lights?

The problem is frequency control and avoiding spikes. You need to ask generator
suppliers what their equipment is suitable for powering.

Michael Chare

After serious thinking Grunff wrote :
How exactly would it be dangerous if you have switched off your main breaker
(i.e. both live and neutral)?

--

I have already written a reply to this, but it appears not to have
turned up.

Trying hard to remember the main points I made:-

Reason A.
1. Supposing someone turned the breaker back on?
2. Supposing that the breaker were faulty and failed to actually
disconnect?
3. Supposing the OP forgot to switch the breaker off?

In all the above he would be back feeding the output of his generator
into what an engineer working just down road would consider to be an
isolated cable. It could just as easily be an engineer working on an
11Kv line which fed a transformer, being back fed.

The electricity supply authorities go to great lengths to ensure lines
are turned off, locked out with permissions to work and along comes our
OP with his genny and makes the line live though ignorance or accident.
They work with several layers of safety proceedures, developed over
many years, for very good reasons. They do work on live cables, but
they take proper precautions whilst doing this.

Even if all that happens as a result of any of the above scenarios were
the connection of the genny to the mains, and the mains was restored
with the genny still connected, then that genny would be smoke. That is
if you were lucky. It would be out of sync, and most likely running at
a diffferent speed to the mains frequency.

Reason B.
The OP was suggesting using a cable to link the genny with a 13amp plug
fitted at BOTH ends of the cable. Possession of such an item is highly
illegal because it could be used for this purpose and even if not
around for this specific purspose, extremely dangerous and against the
regulations. It is not a minor infringement. Consider for a moment, if
someone were to plug one end into a socket. The pins of the other plug
become live and very accessible. Someone is killed and you would
certainly be facing a man slaughter charge.

They only acceptable way is a properly constructed, specially designed
for the job, change over breaker. This would be properly interlocked so
there is no possibility at all of the two supplies being
simultainiously connected.

You apparently consider the risks small, I consider the above
possibilities highly likely and almost certain to happen.... That is
why they legislate against it, that is why there are regulations.

....and finally, how safe would you feel in a damp hole in the road
handling a damaged cable which was supposed to be dead, with only the
OP's relatively poor quality main breaker between you and his
generators 240v? Or the possibilty of his wife or his kids switching
that breaker on? Would you trust someone who even needs to ask this
sort of question with your life?... No disrespect to the OP himself, he
just asked the question.

--


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org

On Thu, 11 Mar 2004 02:12:16 GMT, Harry Bloomfield wrote:

... mains was restored with the genny still connected, then that
genny would be smoke. That is if you were lucky. It would be out of
sync, and most likely running at a diffferent speed to the mains
frequency.

It wouldn't stay that way for long. The mains would motor such a small
generator into sync in very short order. Wether the alternator would
survive is debateable and the engine might not like it that much
either but if it stalled it would be started again...

Not something you see happen very often these day on the grid, a
generator being bought online out of phase/sync. I've only seen the
effects as a consumer once probably in the early 80's. Voltage going
up and down from full to not al lot at about 1Hz with amplitude of the
voltage excursions decaying over about 5 to 10 seconds.

--
Cheers
Dave. pam is missing e-mail

In uk.d-i-y, Harry Bloomfield wrote:

The OP was suggesting using a cable to link the genny with a 13amp plug
fitted at BOTH ends of the cable. Possession of such an item is highly
illegal because it could be used for this purpose and even if not
around for this specific purspose, extremely dangerous and against the
regulations. It is not a minor infringement. Consider for a moment, if
someone were to plug one end into a socket. The pins of the other plug
become live and very accessible. Someone is killed and you would
certainly be facing a man slaughter charge.

I agree with the main thrust of what you're saying - crude backfeeding
into the domestic circuits through a "double-plug" lead is an accident
waiting to happen, and is thoroughly irresponsible, both because of the
specific live-pin-double-header-lead issue, and the absence of reliable
isolation from the main supply. I think you overstate the legal position
on such a lead, though: while in the context of the more stringent
Electricity At Work regs, and in the possession of an allegedly professional
electrician, such a lead would justifiably raise eyebrows, I find it
hard to believe that even in those circumstances simple possession of
such a lead would be "highly illegal". It would be the *use* of such a
lead in inappropriate circumstances - admittedly, just about all uses
which see 'normal' full-on 240VAC passing through it would be in that
category! - which would give rise to serious criminal or civil liability.
(F'r example, if such a lead is photographed for an IEE "horror of the
month" gallery, I don't think either the photographer or the publishing
organisation would be doing anything "illegal"; I can also imagine using
such a lead to short out selected sections when investigating layout or
(lack of) continuity in a (suitably isolated) ring, passing only
resistance-measurement currents-n-voltages through it and the wiring under
test.)

But it's a thoroughly, dismally bad idea to use this kind of a gung-ho
approach to wiring in a 'semi-permanent' backup genny: and the recent
threads on genny connection and earthing arrangements have gone over the
issue in pretty comprehensive detail. So why do I bother picking up on
the "highly illegal" point? Because blustering that "practice X is
Highly Illegal" (without giving *reasons* why practice X is
thoroughly daft - which you did also!) is at best ineffective, and at worst
gives rise to a counterproductive backlash - "all these stupid rules and
regulations, trying to tell me how to do things in my own home, stuff the
lot of them, it's just like the CORGI monopoly, yada yada yada". For the
regs where there's a sound reason, explaining the reason is a great deal
more educational than just saying "it's not allowed": as a close analogy,
I expect Ed Sirrett's calm explanations of the need for gas purging,
no-pressure-drop testing, and similar minimum-practice procedures as
part of gas work have helped convince a number of our readers who might
otherwise think "I can solder CH pipes, why not do the gas ones too?" that
they may *not* be fully "competent persons" to undertake their own gas
work...

Cheers, Stefek

In uk.d-i-y, Dave Liquorice wrote:
On Thu, 11 Mar 2004 02:12:16 GMT, Harry Bloomfield wrote:

... mains was restored with the genny still connected, then that
genny would be smoke. That is if you were lucky. It would be out of
sync, and most likely running at a diffferent speed to the mains
frequency.

It wouldn't stay that way for long. The mains would motor such a small
generator into sync in very short order. Wether the alternator would
survive is debateable and the engine might not like it that much
either but if it stalled it would be started again...

Not something you see happen very often these day on the grid, a
generator being bought online out of phase/sync. I've only seen the
effects as a consumer once probably in the early 80's. Voltage going
up and down from full to not al lot at about 1Hz with amplitude of the
voltage excursions decaying over about 5 to 10 seconds.

On a "medium" scale (i.e., "massive" for us d-i-y'ers, "tiny" for CEGB
types) our site had an Interesting experience concerning a diesel backup
genset and the incoming mains feed playing repeated "up-again, oops,
gone again, up again, down, up, brownout, down, up, howja-mean genset's
out-of-phase, GOSH what a lot of molten copper, those busbars weren't
really designed as a fusible link, were they?" incident some 10+ years ago
- the full details of which were (oddly enough) never explained with complete
transparency and full engineering detail, given the blurred responsibility
issues between site facilities, multiple design and implementation subbies,
the supply company, and the multiple entities working on big-ass construction
for the large MoD procurement-executive site next door at the time ;-)

Stefek

On 11 Mar 2004 10:38:06 GMT, wrote:

... our site had an Interesting experience concerning a diesel
backup genset and the incoming mains feed playing repeated
"up-again, oops, gone again, up again, down, up, brownout, down, up,
howja-mean genset's out-of-phase, GOSH what a lot of molten copper,
those busbars weren't really designed as a fusible link, were they?"
incident some 10+ years ago

Might have been the same incident if you are refering to HP and MOD to
the north of Bristol... Though TBH the incident I'm thinking of must
be nearer 20 years ago now rather than 10.

Of course in a properly designed system once the mains goes and you've
switched over to your generators you should stay on your generators
until you've had it confirmed from the supply company that the
restored supply is secure and isn't going to go off again. Auto start
your generators but don't auto switch back to the mains.

--
Cheers
Dave. pam is missing e-mail

In uk.d-i-y, Dave Liquorice wrote:

Might have been the same incident if you are refering to HP and MOD to
the north of Bristol... Though TBH the incident I'm thinking of must
be nearer 20 years ago now rather than 10.

I think we have a winner! That would be the one... it would be under
20 years ago, since I've only been in Brissle just under that long; and
the MoD site was initially a speculative property development put up in the
?late-80s/very-early-90s? property boom-n-bust, which then stood empty
with the fountain squirting forlornly for a ?couple of years? before HMG
decided that Abbeywood might be a great place to centralise MoD procurment.

Of course in a properly designed system once the mains goes and you've
switched over to your generators you should stay on your generators
until you've had it confirmed from the supply company that the
restored supply is secure and isn't going to go off again. Auto start
your generators but don't auto switch back to the mains.

I do believe this lesson was taken firmly on board after the above
excitement ;-)

Stefek

Chris Hogg wrote in message . ..
As we live in a remote country area and suffer the occasional
power-cut, we are toying with the idea of getting a portable generator
to power the essentials at such times, especially as the predictions
going around ATM don't inspire confidence for the future. The one
we're thinking about is the Wolf 230V/2000W model (I assume AC), from
Screwfix. Probably not cost-effective, but at least it'll keep the gas
c/h, TV, lighting and freezers going. But before we splash out, I have
some questions.

We have a TT system with a 100A/100mA time delayed RCD at the 'front
end', and a split-load CU with MCB's and a 30mA RCD on one half. Is it
acceptable simply to run a cable from the generator to any socket in
the house on one of the ring mains for example, to in effect power the
whole house?

no no no. Thats reserved for people that just got out the nick and are
crossing their fingers they dont go back too soon.


Presumably the front-end RCD would need to be switched
off before connecting the generator, both to avoid powering the
neighbourhood (!) and to avoid nasty things happening when the mains
power comes back on.

too dangerous

Or do I have to power items individually and
directly, independent of the house wiring, using a network of
extension leads?

that would function, although there would be safety issues with it. A
permanently wired separate ring would also work, the ring being
connected to just the gen and not to the grid powered system. You'd
need to comply with the various requirements on that.


If it's acceptable to connect the generator that way, the MCB on the
ring connected to the generator would be powered 'backwards' as it
were, IYSWIM, but the remaining MCB's would still be in 'forward'
mode. Is this OK?

Do RCD's work 'backwards' ? (The power from the house lights would run
from the RCD side back through the RCD to the lighting MCB).

the only one being powered backwards in your dangerous scenario would
be the 30A ring main one. Since the gen has its own 8A breaker and is
most likely incapable of delivering enough current to trip the 30A
breaker, backwardsing is in itself not much of an issue. However other
factors are!

Installs as bad as this are going to produce a high accident and death
rate, and as the installer you would be held entirely responsible for
said death if one occurs as a result of such illegal and irresponsible
actions.

I assume it's a good idea to isolate the high-power items such as the
cooker and the immersion heater, to avoid accidental use and overload
of the generator,

of course the cooker should not be on a 2kW gen, it would either stall
it immediately if powered, or trip it.

although an appropriate fuse in the linking cable
from the generator would probably do just as well.

it probably wouldnt, and probably isnt really good enough is it?

Do the terms 'live' and 'neutral' have any
significance when using such a generator?

both poles are live from a portable generator. I would want to use dp
switched sockets on the genny ring.

Is there anything that it's best not to power from a generator, such
as a computer or other electronic equipment (but what hasn't got
electronic circuits in it these days?), or fluorescent lights?

I wouldnt want to power any portable tronics from such a setup. Small
gens produce enormous spikes when loads switch off, the sort of things
that can roast TVs at the flip of a switch.

If you have a genny ring you could have lights plugged into it left
switched on, so that when the gen starts the backup lights come on. Of
course a couple of battery backup light fittings on the mains would be
far easier and cheaper, and come on instantly and automatically.

I've found gas lighting to be far more practical for power cut backup.
Loss of computer, TV etc, is fairly trivial. Freezers stay frozen for
longer than any power cut youre likely to encounter in Britain. Power
backup systems are more useful in places like America where power goes
down for days at a time.


Regards, NT

"Michael Chare" wrote in message ...
"Chris Hogg" wrote in message
...
As we live in a remote country area and suffer the occasional
power-cut, we are toying with the idea of getting a portable generator
to power the essentials at such times, especially as the predictions
going around ATM don't inspire confidence for the future. The one
we're thinking about is the Wolf 230V/2000W model (I assume AC), from
Screwfix. Probably not cost-effective, but at least it'll keep the gas
c/h, TV, lighting and freezers going. But before we splash out, I have
some questions.

If you want to use your household wiring, you would need some sort of change
over switch so that you either connect to your generator or the normal power
supply.

The reason for this is that you are dealing with alternating current. If you
connected your generator to a live mains power supply it likely would not be
running in phase (and maybe at the wrong speed). This could lead to large
current flows and accompaning fireworks.


My late father used to work for the Central Electricity Generating
Board and he told me they would line up the phases very carefuly
before bringing a powerstation on line. On one occasion they got one
120 degrees out of phase; it broke the shaft that linked the turbine
to the alternator.

R

Many thanks for all the advice.

While it seems that even though what I was suggesting doing is
technically practical, the potential risks (small chance of things
going wrong in my particular circumstances, but _extremely_ serious
consequences if they did) far outweigh the benefits of connecting the
generator to the house wiring compared to simply using extension
cables.

I'm having second thoughts about the whole idea anyway. The object of
the exercise would be to provide power to the fridge/freezer, the c/h
system, some lighting and possibly the TV. But I take on board NT's
comments about the generator output being spiky especially when items
switch in or out, and this can fry electronic equipment. I imagine the
fridge/freezer would be the worst offender here, as IIRC they can be
spiky enough even on the normal mains supply. As I said in my OP,
'what hasn't got electronic circuits in it these days?'. The TV
obviously does, and I expect so does the c/h system (Vaillant Ecomax
VU226E with Honeywell timer). As one of the primary reasons for the
generator supply would be to keep the c/h system running, blowing it
up or not running it in case it did, rather defeats the object of the
exercise! I suppose I could disconnect the c/h system while the
fridge/freezer was running (which need not be very often: as NT also
said, they do keep their cool for quite a while) and vice versa, but
it's all looking much more fiddly than I first imagined.


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net

Chris Hogg wrote in message . ..
Many thanks for all the advice.

While it seems that even though what I was suggesting doing is
technically practical, the potential risks (small chance of things
going wrong in my particular circumstances, but _extremely_ serious
consequences if they did) far outweigh the benefits of connecting the
generator to the house wiring compared to simply using extension
cables.

I'm having second thoughts about the whole idea anyway. The object of
the exercise would be to provide power to the fridge/freezer, the c/h
system, some lighting and possibly the TV. But I take on board NT's
comments about the generator output being spiky especially when items
switch in or out, and this can fry electronic equipment. I imagine the
fridge/freezer would be the worst offender here, as IIRC they can be
spiky enough even on the normal mains supply. As I said in my OP,
'what hasn't got electronic circuits in it these days?'. The TV
obviously does, and I expect so does the c/h system (Vaillant Ecomax
VU226E with Honeywell timer). As one of the primary reasons for the
generator supply would be to keep the c/h system running, blowing it
up or not running it in case it did, rather defeats the object of the
exercise! I suppose I could disconnect the c/h system while the
fridge/freezer was running (which need not be very often: as NT also
said, they do keep their cool for quite a while) and vice versa, but
it's all looking much more fiddly than I first imagined.


How about putting a UPS on the CH? Easier, cheaper. Add 2 battery
backup light fittings and youre all done.


Regards, NT

"Steve Firth" wrote
| N. Thornton wrote:
| How about putting a UPS on the CH? Easier, cheaper.
| and limited to about 20 minutes run time.

You only need a UPS if the supply has to be *uninterruptible*. If the CH is
plugged into a (double pole switched, or unswitched) 13A socket it's easy
enough to unplug it and plug into an inverter+car battery.

Owain

On 12 Mar 2004 02:34:42 -0800, N. Thornton wrote:

How about putting a UPS on the CH? Easier, cheaper.

Already being stated that runtime is not very long with a cheap UPS.
However Mr Plowman has a backup system based around an invertor and
car battery. ISTR he reckons it'll last several hours and my quick 'n
dirty calculations would support that. (50A/hr battery @ 12v = 600W in
1hr. 100w load should mean 6hrs uptime, told you quick 'n dirty...)

Google will return Mr Plowmans posts regarding his setup.

Add 2 battery backup light fittings and youre all done.

Again runtime is a problem most only offer 3hrs max. Power cuts in
this rural location are nearly always 6hrs. And you want the light at
night not during the day but do want them to come on automatically...

--
Cheers
Dave. pam is missing e-mail

"Owain" wrote in message
...
"Steve Firth" wrote
| N. Thornton wrote:
| How about putting a UPS on the CH? Easier, cheaper.
| and limited to about 20 minutes run time.

You only need a UPS if the supply has to be *uninterruptible*. If the CH
is
plugged into a (double pole switched, or unswitched) 13A socket it's easy
enough to unplug it and plug into an inverter+car battery.

I'm not an expert here, but surely if you are running on a generator, which
is loaded suitably, say to 50-60% of its rated output by primarily resistive
loads, say fan heater, then any spikes caused by the freezer compressor
switching in and out would be absorbed upto a point? All electronic
components produced have to be filtered and happy on a wide variety of
voltage and frequency to get a CE certification now anyhow...?

Tim..

on 12/03/2004, Tim (Remove NOSPAM. supposed :
I'm not an expert here, but surely if you are running on a generator, which
is loaded suitably, say to 50-60% of its rated output by primarily resistive
loads, say fan heater, then any spikes caused by the freezer compressor
switching in and out would be absorbed upto a point? All electronic
components produced have to be filtered and happy on a wide variety of
voltage and frequency to get a CE certification now anyhow...?

Generally loading up the generator with a mainly resistive load will
help reduce the spikes and variations in voltage, yes.

--


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org

On Fri, 12 Mar 2004 12:51:20 -0000, "Owain"
wrote:

"Steve Firth" wrote
| N. Thornton wrote:
| How about putting a UPS on the CH? Easier, cheaper.
| and limited to about 20 minutes run time.

You only need a UPS if the supply has to be *uninterruptible*. If the CH is
plugged into a (double pole switched, or unswitched) 13A socket it's easy
enough to unplug it and plug into an inverter+car battery.

Or howabout an inverter plus car battery in the car and it running
(ticking over)? Isn't that what a 'generator' is?

All the best ..

T i m

"Dave Liquorice" wrote in message ill.com...


How about putting a UPS on the CH? Easier, cheaper.

Already being stated that runtime is not very long with a cheap UPS.

Obviously, you would select a UPS that delivers enough run time at
your given load. The load in question is not much.

However Mr Plowman has a backup system based around an invertor and
car battery. ISTR he reckons it'll last several hours and my quick 'n
dirty calculations would support that. (50A/hr battery @ 12v = 600W in
1hr. 100w load should mean 6hrs uptime, told you quick 'n dirty...)

Google will return Mr Plowmans posts regarding his setup.

Sure its an option, but its hassle to use - especially in the dark -
and car batteries dont last well when used like this. I used to have
car battery based backup, but after a while switched to gas.


Add 2 battery backup light fittings and youre all done.

Again runtime is a problem most only offer 3hrs max. Power cuts in
this rural location are nearly always 6hrs.

True. One can add a bigger battery if 3 hours isnt enough. I cant
imagine needing more than 3 hours here, but as you point out,
locations vary.


And you want the light at
night not during the day but do want them to come on automatically...

I dont think it makes any difference in practice. If there were a
daytime power cut and your 2 low power lights came on, it wouldnt be a
problem as far as I can see.


Regards, NT

"Owain" wrote in message ...
"Steve Firth" wrote
| N. Thornton wrote:

| How about putting a UPS on the CH? Easier, cheaper.


If the CH is
plugged into a (double pole switched, or unswitched) 13A socket it's easy
enough to unplug it and plug into an inverter+car battery.

That is a disadvantage of that method compared to a UPS, which is
automatic and instant. If I put power backup in here it will be all
automatic.


You only need a UPS if the supply has to be *uninterruptible*.

The OP doesnt need anything. The question here is which is the better
option, and UPS scores better afaics.

Theres no reason why UPS must be limited to 20 minutes. Any UPS
sufficiently rated can work with any size battery you put on it. A
word about sufficiently rated: the continuous rating will be lower
than the 20 minute rating, that must be considered when buying.


Regards, NT

" Tim \(Remove NOSPAM." wrote in message ...
"Owain" wrote in message
...
"Steve Firth" wrote
| N. Thornton wrote:
| How about putting a UPS on the CH? Easier, cheaper.
| and limited to about 20 minutes run time.

You only need a UPS if the supply has to be *uninterruptible*. If the CH
is
plugged into a (double pole switched, or unswitched) 13A socket it's easy
enough to unplug it and plug into an inverter+car battery.

I'm not an expert here, but surely if you are running on a generator, which
is loaded suitably, say to 50-60% of its rated output by primarily resistive
loads, say fan heater, then any spikes caused by the freezer compressor
switching in and out would be absorbed upto a point? All electronic
components produced have to be filtered and happy on a wide variety of
voltage and frequency to get a CE certification now anyhow...?

Tim..

Hi Tim.

It certainly will improve things, but not solve them. A generator is
an inductive device, and if a load is switched off it will produce an
inductive kick. This is out of all proportion to the spikes on the
mains, and can damage some items. Resistive loading will help with
this but wont eliminate it. Hefty surge suppression can deal with the
worst of it, one of the few apps where I could actually recommend
them.

Regards, NT

On 13 Mar 2004 03:24:25 -0800, N. Thornton wrote:

Obviously, you would select a UPS that delivers enough run time at
your given load. The load in question is not much.

Which isn't going to cheap for the battery, yes you can stick a 50A/hr
battery on the back of 700W UPS and have extended runtime but don't
forget the charging aspect. SLAs are a bit finickity.

Google will return Mr Plowmans posts regarding his setup.

Sure its an option, but its hassle to use - especially in the dark -
and car batteries dont last well when used like this. I used to have
car battery based backup, but after a while switched to gas.

Fuel cells? Now that is expensive. B-)

Hassle I don't think so, ISTR that Mr Plowmans system is automatic
switch over anyway. The CH and/or freezers etc don't need a maintained
supply they won't worry about 30 mins or an hour without power, I
don't get beyond torches for the first 30mins of a cut anyway and
decide what else to do after a phone call to the lecky company.

I dont think it makes any difference in practice. If there were a
daytime power cut and your 2 low power lights came on, it wouldnt be
a problem as far as I can see.

Until it goes dark... Example: Power goes at 1400 (for our normal
6hrs), daylight goes at 1700, when are the emergency lights going to
go off with flat batteries? When do you really need the light? B-)

--
Cheers
Dave. pam is missing e-mail

"Dave Liquorice" wrote in message ill.com...
On 13 Mar 2004 03:24:25 -0800, N. Thornton wrote:

Obviously, you would select a UPS that delivers enough run time at
your given load. The load in question is not much.

Which isn't going to cheap for the battery, yes you can stick a 50A/hr
battery on the back of 700W UPS and have extended runtime but don't
forget the charging aspect. SLAs are a bit finickity.

Whats this persons CH leccy power consumption? I'm guessing allow
100w, until better figures appear. Invertor efficiency 90% so we need
apx 110w from the battery. At 12-13v thats 8A.

Now, for how many hours? If we want 4 hours to 80% discharge (use is
only occasional) then we need 5x8 = 40Ah. 8 hours 80Ah, 12 hours
120Ah.

IIUC SLAs are only finicky about overvoltage charging, and putting a
bigger battery on wont cause that.


Google will return Mr Plowmans posts regarding his setup.

Sure its an option, but its hassle to use - especially in the dark -
and car batteries dont last well when used like this. I used to have
car battery based backup, but after a while switched to gas.

Fuel cells? Now that is expensive. B-)

heh.


Hassle I don't think so, ISTR that Mr Plowmans system is automatic
switch over anyway. The CH and/or freezers etc don't need a maintained
supply they won't worry about 30 mins or an hour without power, I
don't get beyond torches for the first 30mins of a cut anyway and
decide what else to do after a phone call to the lecky company.

yup, its the lights that are more the instant issue. But if hes made
it permanently wired and automatic then that sounds good too.


I dont think it makes any difference in practice. If there were a
daytime power cut and your 2 low power lights came on, it wouldnt be
a problem as far as I can see.

Until it goes dark... Example: Power goes at 1400 (for our normal
6hrs), daylight goes at 1700, when are the emergency lights going to
go off with flat batteries? When do you really need the light? B-)

You can add that feature if you want. If not, youll get so many hours
of power cut covered and no more.


Regards, NT

On 14 Mar 2004 07:48:12 -0800, N. Thornton wrote:

IIUC SLAs are only finicky about overvoltage charging, and putting a
bigger battery on wont cause that.

They really like three stage charging, but I get the feeling that you
already know this but for the benefit of the group. Stage 1 constant
current "boost" at some fraction of the capacityA. Then as the cell
voltage rises switch to constant voltage (approx 2.4v/cell) the charge
current the slowly falls as the charge is "topped up". Finally at as
the cell voltage increases further switch to constant voltage of
approx 2.25v/cell and low current to keep the battery float charged
and counter self discharge.

The actual switching voltages and float voltage vary a bit depending
on the useage of the battery, standby, regular deep discharge etc.

Would the charger in a UPS expecting a certain capacity of battery,
the one it was designed for and thus could do the switching based on
time rather than cell voltage. Thus a bigger capacity battery would
never be fully charged...

I used to have car battery based backup, but after a while
switched to gas.

Fuel cells? Now that is expensive. B-)

heh.

Electricity from gas... oh never mind.

Until it goes dark... Example: Power goes at 1400 (for our normal
6hrs), daylight goes at 1700, when are the emergency lights going
to go off with flat batteries? When do you really need the light?

You can add that feature if you want. If not, youll get so many
hours of power cut covered and no more.

I'd like the light when I need it, automatically, when it's dark. I
don't know of any non-maintained emergency lights that have a photo
sensor to keep 'em off it it's "light".

--
Cheers
Dave. pam is missing e-mail

"Dave Liquorice" wrote in message news:
On 14 Mar 2004 07:48:12 -0800, N. Thornton wrote:


Would the charger in a UPS expecting a certain capacity of battery,
the one it was designed for and thus could do the switching based on
time rather than cell voltage. Thus a bigger capacity battery would
never be fully charged...

Ahhh, problem understood now. But thinking about it, V or i sensing is
much easier than a long timer, so I would expect it would not be timer
governed - but thats no guarantee.


I used to have car battery based backup, but after a while
switched to gas.
snip

Electricity from gas... oh never mind.

Actually that is doable, at least for the more dedicated enthusiast.
In the 90s I saw a Russian paraffin powered thermocouple device, light
the lamp and the thing gave out 12v at something like 3A. Might be a
bit hard to find one though.


Until it goes dark... Example: Power goes at 1400 (for our normal
6hrs), daylight goes at 1700, when are the emergency lights going
to go off with flat batteries? When do you really need the light?

You can add that feature if you want. If not, youll get so many
hours of power cut covered and no more.

I'd like the light when I need it, automatically, when it's dark. I
don't know of any non-maintained emergency lights that have a photo
sensor to keep 'em off it it's "light".

No. Mind you it would probably be quite easy to adapt one: a low R
photocell could just ground the base current in one of the existing
trs, specifically the one that stops the thing lighting when theres
mains. Or using 2Rs, one a photocell, you could feed the battery to
the mains sourced voltage detect point. Then in the day it would think
mains was present and stay off. Maybe anyway.


Regards, NT