Is this to supply current from your house to use inside your garage? Is the
garage door of the metal tilt up and over type (probably without a frame as
such), or is it a wooden door set in a wooden frame? Does the cable have to
go through the door itself?
What effect are you after? Dead flies? Surprised dog?
The basic principles are that voltage determines range and penetration
and energy in joules determines effect.
So, 100kV will get the dog as it lifts its leg still inches from the
door- but 1 joule will leave it only with something to remember. 500V
will need an actual touch - but 500 joules on a damp day will leave you
with a dead horse leaning against the door..
How to do it is dead (hopefully not literally, if the target is larger
than a fly) easy. High voltage generator, with voltage equal to the
range/penetration required, with very limited current capability linked
to energy storage device of appropriate joule capacity for the required
effect. Link storage device to door. The other side to an earth rod.
After that, everything else is bells and whistles. Do you want the
target to remain, or run away? Do you want to tingle, scream or produce
Having read Sue's post can you confirm that you intend to run an electric
current through a metal garage door as a security measure? If so, the door
will need to be of a type of metal that is a good electrical conductor, such
as steel, not aluminium for example. You need to ask on one of the legal
forums regarding how you stand should someone other than yourself be
During the copper crisis in the 60s I installed a number of EHT
cables with aluminium conductors. Had to get permission from the
ministry but no problems at the time.
Same with the aluminium enclosures I used in the 80s and 90s.
Conducted heat and electricity with no problems.
I recall many years ago a neighbour wiring up a spare car engine in
his garage to the electricity supply. He chatted abot it in the pub
and later got a visit from PC Plod and a threat of arrest if anyone
Aluminium forms a surface layer of aluminium oxide when exposed
to air, which is both very hard and a very good insulator.
Some years ago, I was breadboarding a project on the bench which
used a couple of power MOSFETs to switch 240V mains. Not wishing
to permanently mount the MOSFETS at this stage, I just used a
bulldog clip to temporarily clamp a MOSFET to a lump of aluminium,
making a mental note not to touch it as I hadn't bothered with the
insulating washer and heat conductive grease between the live tab
and the aluminium. After testing that for correct operation, I
clamped the second MOSFET to the same lump of aluminium. The
circuit all worked fine. It was only when disassembling it to
build the final version that it dawned on me that the mounting tabs
had 240V AC difference between them, and it was just the surface
aluminium oxide layer which was preventing a short circuit.
[email address is not usable -- followup in the newsgroup]
If you are looking for a theft deterrent, try a small electric fence unit.
HT side to door (handle), earth to earth spike in ground.
But if the door can be accessed by the public, you could be in deep doo-dah
if anyone was hurt.
It's the reason that it's a legal requirement that any electric fence
within a certain distance of any sort of public thoroughfare must be
marked with large signs indicating that it is an electric fence. The
signs must be repeated every 50 metres or so.
Huh!? Our electric fence measures at least 5kv and I can assure you
it gives you quite a kick if you touch it. It did in fact knock me
briefly unconscious once when I drove into it on our ride on mower and
the wire happened to touch my head.
Pigs are notorious for touching electric fences frequently. It's said
that if you turn an electric fence off:-
Pigs will be through within the day.
Cows, goats etc. will be through within a week.
Horses will never notice (certainly true in our experience!)
But 50v won't do any good as a deterrent, even 30 years ago. It's possible
that the initiator of the voltage (e.g. a battery) was 50 v but this voltage
would have to be stepped up to something useful.
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