Our lifestyles in North America have become increasingly dependant on the
power that is delivered from the electrical utility.
It has become important to us to provide power during an outage for
necessities like the freezer, furnace, or well pump, and for maintaining
our hobbies by keeping power available for the computer, TV, sewing machine
and our ham radio gear.
How we do this can effect or even destroy the life of the lineman who is
trying to restore the power.
In his question, Pete Smith hits a core safety element which is covered by
a part of both the National Electrical Code and the Canadian Electrical
Code for very good reason. Look at his Query:
> My QTH loses power fairly often in the winter. This is critical only
> because my well pump is electric, but in some circumstances (including
> CONTESTS) I'd also like to be able to keep the radio running, tho
probably
> not QRO ;^}.
>
> Anyway, in the interest of simplicity and low cost, I had thought to use
a
> currently open 220 volt outlet in my garage as the input for my generator
> power. So if I lose the mains, I would open the main breaker on my power
> panel (isolating my house from the mains), plug the generator into the
220
> outlet (it's a 220 genny, natch) and start it up. When I see the
> neighbors' lights come back on, I turn off and unplug the generator, and
> then close the main breaker to restore power.
>
> Anything wrong with this scenario?
>
Yes, there is indeed something wrong with this scenario...
The code recognizes deaths that have occurred when power users have
energized the home electrical systems and backfed through the main breaker,
into the line, through the transformer, and out on the distribution line at
a range from 4.8 to 34.5 kilovolts.
The code provisions require that a double-pole, double-throw switch (DPDT)
be inserted so that the load is on the "blades" (common) of the switch and
the two sources are each of the sets of poles.
The sections also go on to require grounding methods for assuring that the
Neutral (the white wire) remains safe, but that is another issue.
The purpose of the DPDT switch is to make it impossible for the
homeowner's generated power to injure or kill the lineman.
A system in which someone else's life depends on YOU remembering to do
things in a certain order when you are in the dark and under stress is
extremely dangerous. If you forget, get the order wrong, or accidentally
leave the generator running when you close the main breaker to your house
you have created a hazard.
If you are considering using a generator for running cord connected
appliances, just run a cord to each from the generator. If, however, you
are considering using the generator to energize fixed appliances, lighting,
and convenience outlets, have a licensed electrician install a DPDT switch
at your house mains for the generator. These switches can be used to
provide power to the whole house or can be sectionalized to just cover key
appliances and circuits which you deem as vital.
Take time to do it right.
J., VY1JA
jallen@polarcom.com
J., VY1JA
jallen@polarcom.com
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