On 12/13/2013 11:56 AM, Pete C. wrote:
bud-- wrote:
On 12/12/2013 7:13 PM, The Daring Dufas wrote:
On 12/12/2013 5:10 PM, Pete C. wrote:
Nate Nagel wrote:
On 12/12/2013 05:49 PM, Pete C. wrote:
The Daring Dufas wrote:
On 12/12/2013 3:12 PM, Pavel314 wrote:
I recently hooked my generator into the main box, with
a lock-out device of course. If the power goes out,
I'll turn off the main switch to the street manually
and flip to generator power.
The problem is how to know when the street power is
back on, other than looking down the street to see if
the neighbors have lights on again. When I just ran
extension cords from the generator to the well,
refrigerators, etc., during an outage, when the power
started up again various lights would light up around
the house as they had been on and were still
street-connected. Now, everything is disconnected from
the street.
It would be nice if there were some sort of induction
device I could clamp on the main line coming in from
the street which would light up an LED if there were
power in the line, but if there's no current actually
flowing I don't see how it would pick up the potential
voltage in the line. Is there such a thing available or
will I have to invent one?
Paul
Some utility meters have LEDs that indicate there is power. A
'non-contact' voltage tester might indicate if held next to the
meter in the right spot. I don't know of a simple method other than
that I would use to show the power is back on.
Years ago, I installed some taps for roadies to hook up
lights for the stage in a night club. To let them know
that the power was on the box at the end of the conduit,
I installed a neon pilot light for each phase. In your
case, you can get voltage sensors that can be wired to an
alarm or flashing indicator light to let you know when
your main power comes back on or just wire up a standard
wall light or an exit sign with your own panel reading
"POWER". ^_^
TDD
Along those lines I installed a pair of neon indicators
mounted to a metal box cover, installed in a metal
electrical box and connected to my panel with a metal
offset nipple. They are connected to the input side of the
main breaker directly, being ~18ga wire and enclosed in
metal enclosures if something fails they are self fusing
and can't start anything on fire. I use an interlock kit
for the generator connection (Square D kit in a Square D
panel).
So what happens if the #18 wire acts as a fuse? There are a few
thousand amps fault current available at the service. A fault of a
few thousand amps through #18 wire will continue an arc over a
rather long distance. And what will happen with the 'spring' in the
wire - where will the wires go when they are broken at the arc?
If an arc is maintained on the 18ga wire it won't be for long.
Ultimately it will burn back to extinguish the arc in a matter of
milliseconds. Either way there is no chance of it starting a
sustained fire in my house. Safety wise it's not much different than
a wire nut coming loose, something that happens from time to time.
That sounds like a good idea, and probably what I would do
were I trying to do something like this myself, I just wonder
if it's code compliant?
Nope.
No code requirements here so I don't care.
I'm not sure on that, code mostly is concerned with fire risk,
and when enclosed in all metal conduit and box the heat
produced in the mS it takes to vaporize an 18ga wire at fault
currents couldn't possibly set anything outside the enclosure
on fire.
It is a rather different case. But downtown there was a maybe 8
story building that had a fire. They tore it down to the first
floor and basement, installed a ramp, and used what was left as a
parking lot. The original service remained (208/120V), far larger
than needed, with 6 parallel sets of service wires. They cleverly
stored salt for the ramp on top of the service switchgear. The
service wound up with an arc-fault and burned down. Some of the
service wires burned back into the supply conduits. Some of them
were live in the conduit. Some wires welded to the conduit and the
utility couldn't pull them out with a comealong. (The wires were
protected by "cable limiters" at the utility transformer vault.
Do a test with 18ga wire connected across even a 100A breaker, much
less a service drop limited only by the transformer and see if any of
the wire is left. My assessment is that installing any kind of
replaceable fuse presents more of a hazard than the non-replaceable
fuse-link the wire presents.
Many vehicles have a fuse link inside a thick heat resistant silicone
rubber jacket. When the wire melts, it doesn't penetrate the insulation
so it's very safe. You can make your own safe fuse link with #18 wire by
putting it inside some braided fiberglass insulated sleeve like what is
used inside electric motors or appliances with electric heating
elements. ^_^
http://www.electroinsulation.com/ext...-sleeving.html
http://preview.tinyurl.com/ojf2x7h
TDD