JoeSixPack wrote:

wrote in message
...
Jim & Lil wrote:

wrote:

I read a post suggesting that in a power outage, you could flip your
main breaker off to prevent anything going to the lines and killing a
line worker, and use a suicide cord from your generator to you clothes
dryer outlet (240 vac) and then your main panel would serve as your
switch for what circuits are using the generator--and that this would
power both 240 and 120 outlets.

As dangerous as this is, is this even possible?

Sounds possible, and safe, unless you guzzle too much beer. You might
hang a big tag on the generator that says "Turn off the main breaker!"

For the added piece of mind, a generator/main selector switch is a modest
investment.
Power failures can result in stress and confusion that make things like
leaving the main breaker on a virtual certtainty at some point. Why take the
chance to save a few bucks.


...One thing that was constructive in my replies is that even with your
main braker shut off, you may be still feeding power down the line via
the neutral wire...

That seems a very unlikely hazard, since it requires 1) a grid power
failure, and 2) a hot to neutral connection that doesn't blow your own
breaker, and 3) a neutral wire that doesn't end up attached to ground
somewhere outside your house.

Nick

Unless I'm mistaken, some 240V outlets do not have the neutral wire
connected to the mains. Only a ground wire, which is insufficient to power
the 120V circuits. This would result in 240 service only in the house
wiring, when feeding in from a generator.

You are partially mistaken. Some older 240v outlets indeed do not have a
neutral connection, however newer ones do (code change). Since the
ground and neutral are required by code to be bonded at the service
entrance panel you will get the same functionality even if you're
feeding an older dryer outlet with no dedicated neutral i.e. using the
ground as a neutral.

The ground on the circuit may be a gauge lighter wire than the main
conductors which would limit your circuit capacity if you had a large
generator (~7kw or larger), but most people doing a dryer outlet
backfeed will have 5kw or smaller generators in which case even a
reduced gauge ground on a dryer outlet has adequate capacity.

Additionally since not only are the ground and neutral requited by code
to be bonded at the service entrance panel, there is also a required
ground rod (or two) connection at the service entrance panel which makes
it all but impossible to backfeed any power down the line if the main
breaker is off. The additional grounding of the utility system neutral
every few poles provides yet another level of protection.

The true risks are 1. Forgetting to shut off the main breaker, and 2.
Forgetting the danger of the double-male "suicide" cord and proper
connection / disconnection sequences.

Pete C.