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

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

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

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

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

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

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

TIA.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

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

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

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

Make up a very dangerous lead with the generator connected to one end and a
3 pin plug on the other, then plug this into a socket on your ring main.
This will back feed the whole ring main, so ensure only the devices you want
to run (taking into account the power of the generator) are switched on.

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

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

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

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

Cheers,

Paul.

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


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

--
Pete Cross

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

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

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

Make up a very dangerous lead with the generator connected to one end and
a
3 pin plug on the other, then plug this into a socket on your ring main.
This will back feed the whole ring main, so ensure only the devices you
want
to run (taking into account the power of the generator) are switched on.

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

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

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

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

Cheers,

Paul.

In article ,
"Pete Cross" 1@2 writes:
"One of the easiest ways to distribute your generator power is to "back
feed" it into a ring main."

Isn't that a bit dodgy ?

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

if someone half reads your posting and fails to
absorb the bit about turning off the isolator then you run the risk of
electrocuting some poor sod at the sub-station fixing your power line.

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

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

--
Andrew Gabriel

In an earlier contribution to this discussion,
Andrew Gabriel wrote:


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

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


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

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

I still need some advice please with respect to earthing - and spike
protection, if necessary, for the boiler electronics.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

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

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

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

Tim.

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


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

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

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

Paul.

On Thu, 8 Jan 2004 13:25:55 -0000, Paul W wrote:

snip

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

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

Make up a very dangerous lead with the generator connected to one end and a
3 pin plug on the other, then plug this into a socket on your ring main.

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

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

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

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

Make up a very dangerous lead with the generator connected to one end
and a
3 pin plug on the other, then plug this into a socket on your ring main.

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

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

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

It is only bad advice if not followed correctly.

Paul.

In article ,
"Paul W" writes:

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

It is only bad advice if not followed correctly.

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

--
Andrew Gabriel

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

It is only bad advice if not followed correctly.

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

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

--
*In "Casablanca", Humphrey Bogart never said "Play it again, Sam" *

Dave Plowman London SW 12
RIP Acorn

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

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

Paul.

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

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

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

--
Chris Green

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

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


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

Paul.

On Thu, 8 Jan 2004 15:04:00 -0000, "Paul W"
wrote:

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

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

PoP

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

On 08/01/2004 Paul W opined:-
One of the easiest ways to distribute your generator power is to "back feed"
it into a ring main.

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

Make up a very dangerous lead with the generator connected to one end and a
3 pin plug on the other, then plug this into a socket on your ring main.
This will back feed the whole ring main, so ensure only the devices you want
to run (taking into account the power of the generator) are switched on.

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

--
Regards,
Harry (M1BYT)...

Remove the 'NOSPAM' in my email address to reply.

Free Amateur Radio Courses:-
http://www.ukradioamateur.org

Make up a very dangerous lead with the generator connected to one end
and a
3 pin plug on the other, then plug this into a socket on your ring main.
This will back feed the whole ring main, so ensure only the devices you
want
to run (taking into account the power of the generator) are switched on.

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

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

Paul.

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

Regards,

Paul.

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

Regards,

Paul.

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

I've just finished testing mine. I've installed a double pole changeover
relay in the output from the FCU that feeds the central heating - the coil
of that relay being energised by the mains. If the mains goes off, it
connects to a 150 watt invertor I've just made - using a Vellerman kit as
the basis. It runs off a car battery. It's been on since about 12 o'clock
and the battery is still fine.

At the moment, it's not *totally* automatic, as the invertor has to be
switched on even if left connected to the battery. I might add a second
relay to switch it on when the mains dies, but that would only be strictly
necessary if I wanted the heating to work if I was out when the power
failed.

I'm happy to rely on torches and battery radios etc for the duration of
the cut, as I have a gas hob for any essential cooking.

--
*Husband and cat lost -- reward for cat

Dave Plowman London SW 12
RIP Acorn

I'm late picking this thread up so if someone's already mentioned this
forgive me...
Tradex in Huddersfield had small gennies for sale last weekend for under
£100 - thought about getting one for the garden shed 'cos the thought of
digging out for the mains supply didn't appeal at all and I'd not be using
it for anything big.
Richard

In article ,
Frisket wrote:
Tradex in Huddersfield had small gennies for sale last weekend for under
£100 - thought about getting one for the garden shed 'cos the thought of
digging out for the mains supply didn't appeal at all and I'd not be
using it for anything big.

Hope you haven't any neighbours.

--
*Why are a wise man and a wise guy opposites?

Dave Plowman London SW 12
RIP Acorn

On Fri, 9 Jan 2004 21:08:04 -0000, "Frisket"
wrote:

Tradex in Huddersfield had small gennies for sale last weekend for under
£100 - thought about getting one for the garden shed 'cos the thought of
digging out for the mains supply didn't appeal at all and I'd not be using
it for anything big.

I noticed on the Screwfix home page that they were doing a small genny
too.

You'll have to bear in mind that these small generators provide
typically about 600 watts of useful power. So with a couple of light
bulbs and an average electric drill you are hitting the limits.

And an electric kettle to give a cuppa is out of the question.

I view my small genny as being able to power my CH system and not much
else if the supply company hit difficulties - I'd have to jury-rig the
genny into the CH system so this is very much on the "ideas" charter
rather than a genny sitting waiting to power up. I'm old enough to
remember the electricity strikes of the 70's, and I don't want to go
thru that again if I can help it.

PoP

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

In article ,
PoP wrote:
I view my small genny as being able to power my CH system and not much
else if the supply company hit difficulties - I'd have to jury-rig the
genny into the CH system so this is very much on the "ideas" charter
rather than a genny sitting waiting to power up. I'm old enough to
remember the electricity strikes of the 70's, and I don't want to go
thru that again if I can help it.

I've just finished doing something similar to mine, although I've used a
car battery and invertor as the standby source. But the method is similar
from the safety point of view, and I'd be happy with comments from others
on any improvements.

Like most systems, my CH is all fed via an FCU. After the FCU I've fitted
a DPDT rocker switch marked normal and emergency. In the normal position,
it simply routes the output of the FCU direct to the CH in the normal way.
In emergency position, it routes the output of a mains coil relay - I've
used a triple pole CO type with 10 amp contacts which is readily available
from the likes of TLC or RS etc for about 20 quid including base. With
mains still working the coil is energised and simply routes the mains
through in the normal way. If the mains fails, the relay drops out and
routes the output of my invertor -(or generator) to the CH spur. The
reason for the relay is that the output lead from the generator or
invertor has to be a plug, and this eliminates any chance of mains flowing
back up the lead and making the plug live - or indeed damaging the standby
source. The third pole on the relay is used to switch the invertor on.
Note it actually just switches the electronics, not the battery feed,
which would require a much larger relay due to the current involved. This
extra pole could also be used to control the starter on a self start genny
set.

I've mounted the rocker switch in a matching blank panel to the FCU, and
incorporated the LEDs from the invertor which show working and low battery
volts. The relay is fitted in a steel adaptable box behind it - I'm
fortunate that the CH controls are mounted in the oven housing unit in the
kitched so there's plenty of space behind. The invertor and battery simply
sit in an adjacent kitchen unit - I don't intend it as a permanent
installation.

On tests, I've had the system running for about 6 hours on a fully
charged 50 Ah battery, and it showed no signs of failing. But of course it
will depend on the weather and how hard the pump etc is running. A test
with a 100 watt bulb showed a life of again about 6 hours before the
battery died.

The next thing is whether to fit a battery charger to the system.

--
*If I worked as much as others, I would do as little as they *

Dave Plowman London SW 12
RIP Acorn

On Sat, 10 Jan 2004 10:20:39 +0000 (GMT), Dave Plowman
wrote:

The next thing is whether to fit a battery charger to the system.

Might be a lot cheaper and easier to use a UPS rather than a genny.
That way you've got battery backed up CH 24x7 and never need to worry
about switching over.

Power the UPS from a 13A socket - and if the UPS battery gets a bit
short then unplug and connect the UPS to the genny so that it has an
incoming 240v supply from which to recharge - you can run the genny
for a few hours to recharge the UPS, then off for another few hours,
etc.

And if the leccy companies are still offline then there will be people
on the streets.....and I predict it won't be David Bowie and Mick
Jagger on behalf of charity collections.....

PoP

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

In an earlier contribution to this discussion,
Dave Plowman wrote:


I've just finished doing something similar to mine, although I've
used a car battery and invertor as the standby source. But the method
is similar from the safety point of view, and I'd be happy with
comments from others on any improvements.


Dave - I was very interested in your solution. Does your inverter produce a
sine wave or a square wave output? If the latter, do your boiler electronics
seem happy with it? Have you done anything to eliminate spikes? How is the
CH supply earthed when powered by the inverter?

If you have read my earlier posts (I started this thread!) you will know
that I am planning something similar with a generator - but not with any
sort of automatic changeover.

Until a couple of days ago, my CH was fed by a FCU in the airing cupboard.
There was a very short T&E cable going from the FCU into a 10-way junction
box, into which the boiler, 3-port valve, room stat and cylinder stat are
all connected. The pump (although also in the airing cupboard) is connected
directly to the boiler - and controlled by its over-run stat. This means
that the boiler needs a live connection in addition to neutral, earth and
switched live.

It was thus relatively trivial to change the wiring in such a way that the
whole thing is now powered from the boiler end rather than the the airing
cupboard end of the cable which joins the two. I have now done this, and the
whole thing is now powered from a 13A plug adjacent to the boiler. The
utility room also houses a couple of freezers - which I wish to power in the
event of a prolonged power cut.

The idea is that, when the power fails, I can put the generator in a
suitable location (maybe in the conservatory - not sure yet) with a 4 or 6
way extension lead into which I can plug the heating, freezers plus some
lighting. As stated earlier, I am looking at the Honda eu10i and eu20i
generators as possible contenders. The smaller one (900 watts) appears
adequate *unless* SWMBO decides she needs to use the microwave - in which
case we shall need the 1600 watt model. Even so, forget electric kettles!

FWIW, I've just invested £20 in a plug-in volt/amp/watt meter from Machine
Mart - which is proving useful in determining the consumption of various
appliances. However, I suspect it doesn't show peak loads on switch-on. The
2 freezers take about 250watts each (only when their compressors are
running, of course) and the heating takes a max of less than 150 watts - so
with 900 watts I would still have some leaway for lighting. [Interestingly,
the 3-port valve consumes about 7 watts even when nothing is running].

The things which I still need to bottom out are earthing and spike
protection.

Clearly, when I unplug appliances from the mains, they are no longer earthed
through the mains - even if the electricity board's earth remains intact
during a power cut. The central heating pipes are sort-of earthed, by being
bonded to a steel gas pipe which disappears underground. What else do I need
to do? For example, do I need to connect the generator's earth to a spike in
the ground? What about the generator's neutral (it's single phase, of
course!) - does that need tying down, and if so, to what?

The generators in question both essentially generate DC and use inverter
technology to produce AC. [I presume this is easier than generating AC since
it doesn't require accurate speed control]. I have a concern - don't know
whether it's real or not - that when, for example, a freezer turns on or off
there could be spikes on the AC output and that these might be detrimental
to the components on the boiler PCB [MkI Baxi Solo 70/4PF]. Does anyone have
any comments about this, and any suggestions on what to do. For example, you
can buy extension leads for computer use with built-in spike suppression.
Would one of these help?

TIA.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

On Sat, 10 Jan 2004 10:20:39 +0000 (GMT), Dave Plowman wrote:

I've just finished doing something similar to mine, although I've
used a car battery and invertor as the standby source.
snip
I'd be happy with comments from others on any improvements.

Change the car battery for a "leisure" type battery. Generally car
batteries do not take kindly to deep discharges, a few cycles and they
are dead or have a dead cell.

--
Cheers
Dave. pam is missing e-mail