Me wrote:

In article ,
"Pete C." wrote:

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.

There is one very hugh assumption being made here in this thread.
It seems that everyone ASSUMES that all the houses that are going
to be backfeed, have wiring that is in TOTAL Compliance with the NEC,
and that if it was once in compliance, it is still in compliance, many
years later. Just what happens when the Ground Rod connection corrodes?
When was the last time you checked yours? What about the Neutral/Ground
bonding strap? what is the resistance across that today, in your house?
Do you even know? Seems like very big assumptions to "Me"....

Me

I didn't assume anything, I noted the code requirements which mean that
there would have to be a significant number of violations/failures for
there to be a safety issue past the obvious forgetting to shutoff the
main or the suicide cord which I noted as well.

Remember that even if your ground rod is rust, you've still got a ground
within a couple utility poles unless it is your actual service drop that
is down. It is all but impossible to build any dangerous voltage
relative to ground on the neutral. Even forgetting to pull the main has
a 99.999% probability of killing any small generator or tripping it's
circuit breakers before any dangerous voltage could build on the utility
mains.

Additionally the utility crews are supposed to 1. wear their insulating
gloves, 2. check lines for voltage before handling, and 3. ground lines
before working on them. All of which puts the odds of killing a utility
worker with your temporary generator connection worse than the odds of
winning Powerball. The chances of killing yourself with the suicide cord
on the other hand are much better.

Pete C.