Backfeeding with a portable generator - REAL safety concerns???

[[email protected]]

Hmm.

I knew it needed a dedicated circuit. After I completed the install, I
realized the generator side of the install is not to code since the
other half of the 220v feed from the generator supplies power to other
outlets.

However, it didn't occur to me that a single twist lock outlet on the
grid circuit that the furnace could plug into was a code violation. I'm
guessing it has to do with the possibility of accidently plugging the
furnace cord into another twist lock outlet on a different circuit. I'm not
too concerned with that in my house since the only twist lock outlets are
specifically for the furnace.


As of a few months ago, my town will no longer do any inspections or
issue permits for any plumbing or electrical work done by homeowners.
I interpret that to mean I better not ask my town electrical inspector,
because we are now in a "don't ask/don't tell" environment. Judging by
the work some of the structural and electrical "improvements" the
previous owners of my house did on their own, this seems like a
great way to improve building safety. *sigh* I guess I'll be visiting
the library to see if they have a copy of the NEC with a loophole.

At least in the mean time if I subtract the numerous (several hazardous
and easily avoided) electrical code violations I've taken out of my wiring,
from this one violation I'm still a net improvement in my code compliance
since I've moved in.

It would also be mighty stupid. In my case the furnace is normally
supplied by a 120v circuit.

It should meet code IF you put wheels on the furnace; then it cannot be
considered stationary.

While it wouldn't suprise me if wheels on a gas furnace on a slightly
sloped concrete floor is an acceptable loophole to the NEC, I'd rather
live with a "seemingly safe" electrical code violation than a "seemingly
unsafe" natural gas problem.

 

[Jim Michaels]

breakers can and do go bad. usually they go intermittent or open.
its hard to predict just what will happen each time power is restored,
sometimes nothing bad happens. i think the greater worry would be that you
might have taken a lightning hit through the panel.
i spend a lot of time repairing industrial equipment after a storm as moved
through. a lot of times the root cause is matter speculation. what i have
is a melted gob of goop that used to be a component.

Many UL listed transfer switches use off the shelf household circuit
breakers as their isolation elements (they do add a mechanical
interlock)

This would seem to negate the failed main breaker argument.

A lockout padlock on the main breaker would go a long way toward
removing danger.

In almost every case a back feed situation would result in an
immediate generator failure (engine stalling or circuit breaker
opening) due to loads in neighbor's homes. The exceptions would be
very large generators or a very small isolated line section (no
neighbors).

This all leaves the mistakes happen even to careful people issue.
And in this case a mistake could lead to manslaughter charges.

Bottom line: Use extension cords or intall an approved transfer
switch of some sort.
Remove SPAMX from email address

 

[John Gilmer]

I don't claim to be a NEC code expert, but last time I checked, a
furnace was considered a "stationary appliance" (like a dishwasher)
and thus must accordingly be connected with a hard-wired connection.

Well, "built in" microwave ovens usually plug into a 15 amp outlet. (It's
supposed to be a single circuit and all that but ....)

Likewise, in some places, dishwashers are plugged in. In many places,
garbage disposals are pluged in. Likewise, window Air Conditioners are
plugged in.

And in all these cases, there ain't a "twist lock" in sight.

So maybe things are "achanging."

 

[[email protected]]

Many UL listed transfer switches use off the shelf household circuit
breakers as their isolation elements (they do add a mechanical
interlock)

This would seem to negate the failed main breaker argument.

A breaker is a single throw device. It cannot transfer a circuit. It
would be interesting to see the switches you have in mind to get
an idea of how they accomplish a positive transfer. Do you have
a particular make/model in mind?

A lockout padlock on the main breaker would go a long way toward
removing danger.

Only if it is used. And also, only if it is used in the correct sequence.

 

[Paul]

A breaker is a single throw device. It cannot transfer a circuit. It
would be interesting to see the switches you have in mind to get
an idea of how they accomplish a positive transfer. Do you have
a particular make/model in mind?

I do. I just installed a Kubota 30KW diesel generator for a customer and it
came
with a 200amp Cutler-Hammer ATS that uses two 225amp MCBs with a stupid
see-saw mechanism that is operated by a small shaded-pole motor with a crank
and limit
switches. I must say I was not impressed when one of my mechanics had to
manually trip the
see-saw (to gain access to the terminal insulator guard) and the pivot bolt
broke off.
I told the customer that he better hope that doesn't happen during automatic
operation.
See for yourself:
http://www.eatonelectrical.com/NASA...&c=Apubarticles&cid=998666762045&Sec=products

 

[John Phillips]

I tried unsuccessfully to find the post of the individual who stated
that a lineman was killed because he had an inadequate ground in a
situation where there was a back feed from a home generator. I would
be interested in reading any written report but the root cause was not
the home generator but the inadequate personal ground.

I am writing this with a gas driven generator supplying my house in
order to burn up some old gasoline. I have tried to keep the lineman
fatalities to less than 10.

I never qualified as a journeyman lineman but I did spend a lot of
time as a ground man and then managed transmission line crews after I
received my EE degree. I did though join the "Bird On The Line" Club
when I touched 345 kV from an insulated bucket. I also played a key
role in the development of 765 kV hot stick tools and practices.




Regards,

John Phillips

 

[[email protected]]

I do. I just installed a Kubota 30KW diesel generator for a customer and it
came
with a 200amp Cutler-Hammer ATS that uses two 225amp MCBs with a stupid
see-saw mechanism that is operated by a small shaded-pole motor with a crank
and limit
switches. I must say I was not impressed when one of my mechanics had to
manually trip the
see-saw (to gain access to the terminal insulator guard) and the pivot bolt
broke off.
I told the customer that he better hope that doesn't happen during automatic
operation.
See for yourself:
http://www.eatonelectrical.com/NASA...&c=Apubarticles&cid=998666762045&Sec=products

Wow! That sure looks ugly. Thanks for the link!

 

[[email protected]]

Square D part # QCGK3

http://www.squared.com/us/products/...25684f005493cf/$FILE/40272-256-03 English.pdf

"The interlock of the generator kit is designed to allow only one
circuit breaker supply handle (utility or generator) to be in the ON
position at any time."

A metal bracket on a pivot that only allows one of two breakers to be
on.. turn off the main breaker, pivot the bracket and turn on the
generator breaker. If either breaker fails in the ON position there's
gonna be a problem; evidently Square D isn't concerned about that.

Regards,

Jim

Thanks! That looks good. I hope it is made better than the one
Paul described where the pivot bolt broke.

 

[Gunner]

I was called to a home with an electrical emergency were a male plug was
being energized. It was caused by a tenants attempt to backfeed the
dryer outlet. The home had a split buss panel and the dryer breaker was
on the main breaker buss.

Did all the magic smoke leak out of the wires?

Gunner

"At the core of liberalism is the spoiled child -
miserable, as all spoiled children are, unsatisfied,
demanding, ill-disciplined, despotic and useless.
Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke

 

[Tim May]

Did all the magic smoke leak out of the wires?

Darwin plugs often lead to this result, almost as if Sir Charles had
laid out the design in 1859.

Negroes seem to have a close affinity with Darwin, strangely enough.


--Tim May

 

[Roger]

In Backfeeding with a portable generator - REAL safety
concerns??? on Mon, 06 Sep 2004 17:33:07 GMT, by Friday, we read:




Yeah, right. You might, or someone else might.




The remedy is simple. A transfer switch box (which would be part
of the job of a professional installation) is about $90. This has
a fail safe device connected to two switches. The first closes
the main circuit to the power line; the second closes the circuit
to your house wiring. This way there is no danger of backfeeding.




Just install a transfer switch.





Pilot error.

Your best and safest way is to have two receptacles side by side.
then you have your Grid power powering up one receptacle and your
generator powering up the other receptacle. when the grid goes down,
unplug from the grid receptable and plug into your generator plugin.
then it don't matter if you forget anything. the only thing that can
happen at this point is that you'll run out of gas/oil for your generator.

That is the cheapes safest way. AT no time should you have a double
ended male cord. That is too dangerouse, specially if you have kids in
the neighbourhood

 

[[email protected]]

Your best and safest way is to have two receptacles side by side.

The BEST way is to use a transfer switch. The problem
with the two receptacles side by side approach is that
hard wired equipment - such as the control for your
heating system, circulator, igniter, blower (if so equiped) -
won't get power. In addition, the two receptacles side by side
approach is limited. By the time pay for the wiring
for enough receptacles to make practical use of even a small
5 kw generator, you'll spend more than you would if you had
a transfer switch installed.

The OTHER problem with the side by side receptacles is it
almost screams for a double male, which, as you said, should
never be used. But when one has been without power for enough
time and is cold because the thermostat won't work, guess
what happens.