On Mon, 5 Jun 2017 11:47:12 -0700 (PDT), wrote:

On Monday, June 5, 2017 at 1:06:12 PM UTC-4, wrote:
On Mon, 5 Jun 2017 07:26:10 -0700 (PDT), wrote:



And the probability of something coming loose on a typical Daisy chained circuit is a lot higher than with a homerun dryer circuit.

if you want to use a 3 wire 220V system, I suggest you attach an additional safety ground wire to the case of the appliance and connect it to a metal water pipe of other good ground.

m

Since the 60s, most of those 6-30 three prong receptacles are
actually connected to 10/3-wg Romex anyway since that was the standard
way it was manufactured. If you look in the box, you may see the bare
ground bonded to the box and the neutral connected to the receptacle.
Because of the higher temperature/ampacity ratings, stoves may still
be wired with SE cable (2 wire plus ground)

ok, sounds like you are talking about a 3 prong 120 v outlet and what you said is all true.

6-30 IS 240v (an old style dryer receptacle)

but the thread is about 3 prong 220V outlets. One prong is 120v. 2nd is the other 120V and the third prong is neutral and ___there is no ground prong__
which is what can make them dangerous if there is an open fault in the neutral. Code for new installs requires 220V outlets to be 4 prongs to add a safety ground. If you are going to use a older 3 prong 220V output that has no safety ground, i was suggesting that you add a ground wire for safety.



If the neutral opens on a dryer, it probably will not run since the
controls are 120v and so is the motor. With the 6-30 you will have a
hot case tho if you do not add the supplemental ground mentioned up
thread.
Far better than a water pipe is the box for the washer receptacle.
There is too much plastic in plumbing to trust a pipe. Even on "all
metal" systems you still have water softeners, whole house filters etc
and you can't count on people putting a 250.66 bond wire around all of
them.