On Tuesday, September 8, 2015 at 8:15:08 PM UTC-4, Ralph Mowery wrote:
Yes, that remote possibility has always existed, for half
a century. The point is the comment was made that it is "very dangerous".
If it's very dangerous, why do dryers still ship configured for 3 wire cords?
Why do the manufacturers give instructions for using it with 3 wire installs?
Why is it still perfectly code compliant to install a new dryer with a
3 wire cord? There are lots of small safety improvements that have been
made over the years, that doesn't make what was there previously very dangerous.
It is not code compliant to install the house wiring for a 3 wire dryer. A
new socket must be wired for 4 wires.
As there are many old houses that have a 3 wire socket installed, it is ok
to sell a 3 wire cord to match them. I don't know of anyting in the code
book that says you have to change the old wiring in the house, just any new
wiring must be installed in a certain way.
As someone else pointed out , it is not all that much of a need or safey
improvement, but just slightly safer.
Often I think the people in some government safety agency must come up with
some kind of idea no matter how crazy just to keep their job.
On Wednesday, September 9, 2015 at 9:58:25 AM UTC-4, Ralph Mowery wrote:
Agree, there isn't anything in NEC that says you have to update the
4 wire is a better way of doing it. My issue, DPB's issue was
taking exception to the comment that 3 wire is "very dangerous".
If something was very dangerous I'd want it corrected immediately.
The 3 wire vs 4 wire is probably lower down the safety list than say AFCI
and I don't see people calling existing non-AFCI circuits very dangerous.
I said it ___CAN___ create a dangerous shock hazard.
Most dryers are installed next to washing machines whose cases are grounded
With a 3 wire system, all it takes is for the the neutral/ground connection
to come loose anywhere along the line, in the plug, in the panel or in the
appliance which is subject to vibration, and the case of the dryer WILL be
energized with 120V. Now someone doing laundry with wet hands leans one
hand on the washer and one on the dryer and presto....
The dryer in my house is wired with a 3 wire plug and I felt it was too da
ngerous so I added a dedicated ground wire to the dryer case.
I belive the NEC made a mistake when they allowed the 3 wire exception and
now they have corrected that mistake. This is one case where there actuall
y IS added saftey and not just added complication.
On Wednesday, September 9, 2015 at 10:39:44 AM UTC-4, email@example.com wro
he appliance which is subject to vibration, and the case of the dryer WILL
be energized with 120V. Now someone doing laundry with wet hands leans on
e hand on the washer and one on the dryer and presto....
lly IS added saftey and not just added complication.
You're entitle to your opinion and feelings. I've never heard of a single
case where someone was electrocuted, seriously shocked, etc. despite
this "mistake" being used on ovens, ranges, and dryers for half a century.
It's possible for the wire to come undone, but the vast majority are home
runs from the receptacle to the panel, diminishing the possibility of
Apparently the appliance manufacturers agree, because they all
provide install instructions for dryer, ovens, etc that show how to
hook it up for 3 wire. The dryers I've seen, in fact came from the
factory configured for 3 wire and you had to change it to use 4 wire.
If it was creating real world serious events, you would think they
would be getting their pants sued off.
On 09/08/2015 03:21 PM, firstname.lastname@example.org wrote:
Voltage drop in that situation (N/G combined, and dryer running) would
make the dryer case voltage greater than 0. I doubt it would be enough
to qualify as "very dangerous". Probably not even enough to feel if you
licked the dryer.
BTW, unless you were doing open-heart surgery in your laundry room :-)
107 days until the winter celebration (Friday December 25, 2015 12:00:00
AM for 1 day).
Not exactly true (see ex-1)
(B) With Circuit Conductors. By connecting to an equipment
grounding conductor contained within the same raceway,
cable, or otherwise run with the circuit conductors.
Exception No. i: As provided in 250. 130(C), the equipment
grounding conductor shall be permitted to be run
separately from the circuit conductors.
250.130(C) Nongrounding Receptacle Replacement or Branch
Circuit Extensions. The equipment grounding conductor
of a grounding-type receptacle or a branch-circuit extension
shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system
as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure
where the branch circuit for the receptacle or
branch circuit originates
(4) An· equipment grounding conductor that is part of another
branch circuit that originates from the enclosure
where the branch circuit for the receptacle or branch
(5) For grounded systems, the grounded service conductor
within the service equipment enclosure
You are replacing a nongrounding receptacle when you replace a 10-40r
with a 14-30r
There's these three connections:
1. 3-wire cable, shared N/G
2. 4-wire cable, separate n and G
3. as #1, but internal jumper removed and dryer grounded separate from
#1 is somewhat less safe. How is #3 less safe than #2? Is it any better
106 days until the winter celebration (Friday December 25, 2015 12:00:00
AM for 1 day).
On Thursday, September 10, 2015 at 4:35:30 PM UTC-4, Sam E wrote:
I don't believe you can do #3 and be code compliant. It appears what
you're suggesting is to keep the existing 3 wire dryer cord and receptacle
and run a separate ground wire from a connection point at the dryer to
an appropriate point on the grounding system for the house. Code requires
that ground wires be run in the same cable as the conductors. GFRE explained
that there is an exception for the case where you are replacing a non-grounding
receptacle with a grounding type receptacle. So, if you replace the 3 wire
receptacle with a 4 wire receptacle, you would use that exception, ground
the receptacle to an allowed point on the grounding system, and then change
to a 4 wire cord. Unless you use that exception, a separate ground wire
is not code compliant. I think I have that right, GFRE can weigh in.
Purely from a safety standpoint, if you did what you suggested in #3,
I don't see it as a safety issue, if otherwise done right, the dryer
would be grounded. But safe and code compliant are not always the same
thing. And if #3 were done right, while I believe it's a code violation,
from a functional standpoint the grounding effect would be the same
as #2 and having a ground would be better than #1. The issue here is
do you want to now create a code violation while marginally
improving a perfectly code compliant, widely used setup? If you go
to sell the house, no home inspector would fail a 3 wire arrangement.
But if he sees a ground wire coming out of the dryer separately,
going who knows where, there is a good chance he would flag it.
Also, I think I still was right, that what Mako suggested, which
I believe is actually your #3 method, is a
code violation, though I focused on the wrong part of it. He
"Its simple enough to make it better. Use a 4 wire plug or add a
supplemental ground wire."
I said that would not be code compliant because the ground would
not be in the same cable, assuming it is cable, which is reasonable.
As GFRE pointed out, there is an exception that allows that. But
to use that exception, you'd still have to change to a 4 wire receptacle
and use a 4 wire plug. You can't keep the 3 wire cord/plug/receptacle
and just add the ground wire directly to the dryer. That's my
interpretation, again, GFRE can weigh in.
On Fri, 11 Sep 2015 05:11:09 -0700 (PDT), trader_4
On a 3 wire connection you still need the bonding jumper in the dryer,
no matter what.
They used to tell you to run a ground wire to the cold water pipe and
some even included a short green wire but that went away years ago.
There is still a tapped hole for the grounding screw with the ground
symbol in old designs but I assume it is just because they never
changed the design for the back cover.
If you want to run a supplemental wire from the dryer case to the 120v
box for the washer, I am not sure what article you are breaking. It
just will not be the only ground you need.
Some might argue that you are putting objectionable current on the EGC
for the washer (250.6) but having the 2 cases bonded together is
safer than not.
On Friday, September 11, 2015 at 10:59:53 AM UTC-4, email@example.com wrote:
It's safer from the standpoint of the two cases then being grounded
and at the same potential. But from a system standpoint, I'd say it
is problem, for the reason you just gave. With the dryer now using
the washer circuit as part of it's combined neutral and ground
path, the ground wire of the washer back to the panel becomes a
current carrying conductor for part of the 120V dryer load, something
that a person working on the washer circuit isn't going to be expecting.
On Friday, September 11, 2015 at 1:51:53 PM UTC-4, Sam E wrote:
Well, I believe GFRE posted that's a code violation, or at least something
is wrong with it:
"On a 3 wire connection you still need the bonding jumper in the dryer,
no matter what. "
Though I agree that from what I see, if you're going to add a separate
ground, you're method would be safer, because there would be no current
in the ground. But the 100% code compliant
way would be to replace the receptacle and cord with 4 wires, and
simply connect the new separate ground wire to the receptacle and
attach the other end to one of the approved grounding points permitted
by the code exception. It's also not likely to get squawked by a
home inspector, where a ground wire attached directly to an appliance
that is also plugged in is almost surely going to attract attention.
This is a private residence, which I'm not about to sell. I'm more
concerned with safety here than code.
I do like the idea of changing the receptacle (and dryer cord) better
than just adding a ground wire. I wish I had thought of that. For one
thing, it makes it a normal installation as far as the dryer is concerned.
Another problem here is where to connect the ground. The cold water pipe
is probably OK for now but there is always the possibility of problems
later. The washer receptacle is grounded but only #12.
105 days until the winter celebration (Friday December 25, 2015 12:00:00
AM for 1 day).
On Friday, September 11, 2015 at 2:01:32 PM UTC-4, Sam E wrote:
Well, you've identified more problems, which is where it's
code compliant to attach the ground wire and what size must it
be. The water pipe is almost always out, unless it happens
to meet the narrow reqts outlined in the exception. Washer
receptacle would be OK, but to be code compliant, it would have
to be a #10 for a 40 amp dryer circuit. I could live with it
being connected to #12, but then I can live with the dryer being
3 wire and 100% code compliant as is, just like millions of homes
built prior to about 2000.
of the tough
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