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