My south facing greenhouse is a lean-to up against the house wall. We
put electricity in for lighting and an electric thermostatically
controlled heater. The wires are run through that yellow plastic
ducting and have been in place now for about 5 years.

Unfortunately there was a problem with the wires when had that really
cold weather recently..........
Of course I did not notice that the heater had not been on until
several plants were well and truly frosted :~((

I have a few questions in connection with this:

1) There had obviously been a short circuit and when we investigated
saw that the wires were sort of dried out (if that makes sense) and
frizzled at the ends. Could this be due to the really hot
temperatures in the GH during the summer months ?? If so what should
we do to stop a repeat of the problem ?? (I do use shading but it
still gets HOT)

2) Is there special wire one should use?

3) or special insulation ?

4) Will the fuchsia's be OK ?? The few leaves that were still on the
plants are limp and frosted, but the stems show green when scraped.

Jenny

Sounds like loose connections (high resistance)heating up under load
(particularly at the ends).
Most cables will be fine at any temp a greenhouse will reach

"JennyC" wrote in message
...
My south facing greenhouse is a lean-to up against the house wall. We
put electricity in for lighting and an electric thermostatically
controlled heater. The wires are run through that yellow plastic
ducting and have been in place now for about 5 years.

Unfortunately there was a problem with the wires when had that really
cold weather recently..........
Of course I did not notice that the heater had not been on until
several plants were well and truly frosted :~((

I have a few questions in connection with this:

1) There had obviously been a short circuit and when we investigated
saw that the wires were sort of dried out (if that makes sense) and
frizzled at the ends. Could this be due to the really hot
temperatures in the GH during the summer months ?? If so what should
we do to stop a repeat of the problem ?? (I do use shading but it
still gets HOT)

2) Is there special wire one should use?

3) or special insulation ?

4) Will the fuchsia's be OK ?? The few leaves that were still on the
plants are limp and frosted, but the stems show green when scraped.

Jenny

On Fri, 27 Dec 2002 18:16:19 +0000, JennyC wrote:



1) There had obviously been a short circuit and when we investigated saw
that the wires were sort of dried out (if that makes sense) and frizzled
at the ends. Could this be due to the really hot temperatures in the GH
during the summer months ?? If so what should we do to stop a repeat of
the problem ?? (I do use shading but it still gets HOT)


A short circuit? If there had been a short circuit then a fuse or circuit
breaker should have open circuited and turned off your electricity supply
to your greenhouse before anything dangerous can happen.

Wires can heat up but if you have a correct fuse rating then this safely
protects the wires from short/overloads and therefore cannot heat up from
short or overload.

Dried out and frizzled at the ends? However, where wire connects to
another piece of equipment then a bad connection certainly can result in
very hot temperatures - so you need to make sure that all the conenctions
are good.

Also, you want to keep water away from the electricity supply.

2) Is there special wire one should use?

Mains cable capable of carrying current to your lighting/heater. Look at
the power rating of your lighting/heater - add up the current both take
and ensure your cable can carry this easily.

Generally appliances only state a power rating rather than current. For
example your lighting may be 60W (w stands for watts). With a 240V mains
electricity supply (UK) the current taken by your lighting is 0.25 amps.

(Current in amps is calculated by dividing the rated watts by
the voltage (240 in the UK), 60 divided by 240 = 0.25A. Note that some
applicances are rated in KW (kilowatts) where 1KW = 1000W.)

Get a current for your heating system. Add this to your lighting current
to give you your total current - then make sure your wire can handle
this. Some common wire ratings are 3A, 6A and 10A.


3) or special insulation ?

Must be suitable for mains use. Greenhouse temperatures won't be a
problem.

If you don't know too much about electricity then you could always get an
electrician to look at it from a safety point of view - he /(she) would
be able to tell you if you need to do anything to ensure it is safe in a
couple of minutes.


PT

SNIP
4) Will the fuchsia's be OK ?? The few leaves that were still on the
plants are limp and frosted, but the stems show green when scraped.

Jenny

Our fuschias stayed outside in the containers for years 'til someone said we
should protect them from frost. We never actually lost one, but they didn't
increase from year to year either. They seem tougher than is normally
supposed, but I presume this depends on varieties, and we do live near
Bournemouth.

Steve

'Twas Fri, 27 Dec 2002 19:16:19 +0100, when "JennyC"
enriched all our lives with these worthy thoughts:


4) Will the fuchsia's be OK ?? The few leaves that were still on the
plants are limp and frosted, but the stems show green when scraped.


I can't help with the lecktrickery questions, but it's worth
hanging on to the fuchsias, as they may well sprout new shoots over
the next 6 weeks or so as we head for spring.

If you lose any plants completely, let me know - I have
cuttings of the cuttings you kindly sent me when I lost my entire
stock 2 winters ago.

--
cormaic URG faqs/webring - www.tmac.clara.co.uk/urgring/
Culcheth Garden - www.tmac.clara.co.uk/garden/
Warrington Paving - www.pavingexpert.com/
Peoples' Republic of South Lancashire

cormaic CAN BE FOUND AT borlochshall.co.uk

"cormaic" wrote in message
...
'Twas Fri, 27 Dec 2002 19:16:19 +0100, when "JennyC"
enriched all our lives with these worthy
thoughts:


4) Will the fuchsia's be OK ?? The few leaves that were still on
the
plants are limp and frosted, but the stems show green when scraped.

If you lose any plants completely, let me know - I have
cuttings of the cuttings you kindly sent me when I lost my entire
stock 2 winters ago.

My goodness, is it already two years ago.........
Doesn't time fly :~))

Jenny

"Paul Taylor" wrote in message
news
On Fri, 27 Dec 2002 18:16:19 +0000, JennyC wrote:

1) There had obviously been a short circuit and when we
investigated saw
that the wires were sort of dried out (if that makes sense) and
frizzled
at the ends. Could this be due to the really hot temperatures in
the GH
during the summer months ?? If so what should we do to stop a
repeat of
the problem ?? (I do use shading but it still gets HOT)

A short circuit? If there had been a short circuit then a fuse or
circuit
breaker should have open circuited and turned off your electricity
supply
to your greenhouse before anything dangerous can happen.

Yes - the circuit breaker cut in, which meant the electricity was cut
of and therefore the temperature dropped to below freezing out there
:~((

Wires can heat up but if you have a correct fuse rating then this
safely
protects the wires from short/overloads and therefore cannot heat up
from
short or overload.

OH


Dried out and frizzled at the ends? However, where wire connects to
another piece of equipment then a bad connection certainly can
result in
very hot temperatures - so you need to make sure that all the
connections
are good.

Also, you want to keep water away from the electricity supply.

The wiring runs through the house wall and along a dry brick wall.


2) Is there special wire one should use?

Mains cable capable of carrying current to your lighting/heater.
Look at
the power rating of your lighting/heater - add up the current both
take
and ensure your cable can carry this easily.
Generally appliances only state a power rating rather than current.
For
example your lighting may be 60W (w stands for watts). With a 240V
mains
electricity supply (UK) the current taken by your lighting is 0.25
amps.
(Current in amps is calculated by dividing the rated watts by
the voltage (240 in the UK), 60 divided by 240 = 0.25A. Note that
some
appliances are rated in KW (kilowatts) where 1KW = 1000W.)
Get a current for your heating system. Add this to your lighting
current
to give you your total current - then make sure your wire can handle
this. Some common wire ratings are 3A, 6A and 10A.

I'll get the technical half to have a look at that tomorrow :~)

3) or special insulation ?

Must be suitable for mains use. Greenhouse temperatures won't be a
problem.

We used proper EU standard stuff !

If you don't know too much about electricity then you could always
get an
electrician to look at it from a safety point of view - he /(she)
would
be able to tell you if you need to do anything to ensure it is safe
in a
couple of minutes.
PT

Thanks PT
Jenny

"snafu steve" wrote in message
...
SNIP
4) Will the fuchsia's be OK ?? The few leaves that were still on
the
plants are limp and frosted, but the stems show green when
scraped.

Jenny

Our fuschias stayed outside in the containers for years 'til someone
said we
should protect them from frost. We never actually lost one, but they
didn't
increase from year to year either. They seem tougher than is
normally
supposed, but I presume this depends on varieties, and we do live
near
Bournemouth.
Steve

I'm in inner city Rotterdam, but the temperature did drop to about -8
.................

Jenny

"JennyC" wrote:

Hello JennyC

J 1) There had obviously been a short circuit and when we
J investigated saw that the wires were sort of dried out (if
J that makes sense) and frizzled at the ends. Could this be

If they looked burnt then yes, probably a bad connection.

Other possibilities include contact with polystyrene (sort of "melts"
the PVC) and mice (teethmarks).

J due to the really hot temperatures in the GH during the
J summer months ?? If so what should we do to stop a repeat of
J the problem ?? (I do use shading but it still gets HOT)

Temp increases the resistence of the wire, but I doubt it's getting
hot enough to damage the PVC coating itself.

J 2) Is there special wire one should use?

Normal PVC twin and earth is usually ok, but you really should have
that section protected by a RCD if its not already.

J 3) or special insulation ?

I'd be more worried about the load of that heater. If it's a biggy
then it might be too much for the wire, time to do some calculations
and bear in mind that the length of the run reduces the load the wire
can carry. uk.d-i-y is a good group for more detailed info on this
(about where my brain runs out, I'm afraid).

--
Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/

"Simon Avery" wrote in message
...
"JennyC" wrote:

Hello JennyC

J 1) There had obviously been a short circuit and when we
J investigated saw that the wires were sort of dried out (if
J that makes sense) and frizzled at the ends. Could this be

If they looked burnt then yes, probably a bad connection.

Other possibilities include contact with polystyrene (sort of "melts"
the PVC) and mice (teethmarks).

J due to the really hot temperatures in the GH during the
J summer months ?? If so what should we do to stop a repeat of
J the problem ?? (I do use shading but it still gets HOT)

Temp increases the resistence of the wire, but I doubt it's getting
hot enough to damage the PVC coating itself.

J 2) Is there special wire one should use?

Normal PVC twin and earth is usually ok, but you really should have
that section protected by a RCD if its not already.

J 3) or special insulation ?

I'd be more worried about the load of that heater. If it's a biggy
then it might be too much for the wire, time to do some calculations
and bear in mind that the length of the run reduces the load the wire
can carry. uk.d-i-y is a good group for more detailed info on this
(about where my brain runs out, I'm afraid).

--
Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/

Back to the electricity matter, I didn't realise you weren't in UK.I don't
know whether local regulations consider a lean-to greenhouse "outdoors". If
so, they may require an outdoor grade of armour sheathed wire.
Come to think of it, I don't know whether UK regs would consider it outdoors
either. Best to check with sparky.

Steve