No GFCI's and I suspect there may be some need for them in a "shop"
(without knowing what else is in the building).
Two 20A breakers are unused -- both on the same leg (a likely place
to suspect a sizeable imbalance)
The bottom right two-pole breaker feeds a 220V circuit wired black/white
(i.e., the safety "ground" acting as neutral for any appliance
fed from that branch)
On Tuesday, December 29, 2015 at 2:01:18 PM UTC-5, Don Y wrote:
It's actually the reverse. The neutral also serves as a ground for
old circuits installed in the days when it was permitted, prior to a
separate ground being required. A neutral was always required to
support a circuit with both 240V and 120V loads, it can't physically
work without it. The concept of requiring grounds came later.
On Tue, 29 Dec 2015 14:57:18 -0800 (PST), trader_4
Actually only for ranges and clothes dryers for the 40 years or so
that this exception existed but it was still never legal from a sub
panel ... for exactly the reason we are discussing.
The neutral is 5 or 6 volts above ground.
Do you really want to be laying on a concrete slab with a drill that
is putting 5 volts AC in your sweaty hands?
That is why I would really want to see a ground rod or two.
It is going to be a tingle voltage that may or may not trip the GFCI
... if he had any.
Then we could open the "other metallic path" thing if we are still
using the old 3 wire feeder exception.
On Tuesday, December 29, 2015 at 6:52:23 PM UTC-5, email@example.com wrote:
I agree. My point was that on even those old circuits, it was the
neutral that was the essential component of supplying 240/120V.
And when the neutral is shared, it's the ground that's sharing the
neutral, not the other way around. The circuit could work with no
ground. It can't work with no neutral.
On 12/29/2015 4:41 PM, firstname.lastname@example.org wrote:
You don't know that looking *in* the panel. Put a cover on the terminal
Jbox (because you are no longer using that piece of gear) and the
next guy coming along opens it to find white (untaped), black and
copper. Do you think he's going to assume the white is really
a hot and this is a 220V feed? Or, that it's yet another 110V, 20A
240 volt specific outlet you ALWAYS disconnect it at the breaker. That
way there is no chance of ambiguity.
A good idea on any "dedicated" circuit too. If there is nothing else
on the circuit don't just wire-nut it off in the jbox. Either
disconnect, or better yet label and lock out the breaker involved.
Do the *easy* things, first.
- measure at the *main* panel
- measure at the subpanel (already done)
- open the disconnect at the subpanel and remeasure at the main panel
Assuming this isolates the problem to the subpanel:
- remove individual loads from the subpanel (open breakers) and measure
Take good notes.
You should be able to diagnose the problem just from these observations.
I am basically lazy. :> As I think most folks are. I would rather do
the easy things -- take data and THINK about the problem -- than run
around "try this", etc.
Occam's Razor: chances are, it's something in the subpanel/workshop
and NOT something with the utility -- *or* the main panel (not
counting the subpanel tie-in).
Eliminate the workshop and see if the problem persists. If not, tells
you the problem is *related* to the workshop (though may still manifest
in something else).
Far better to be able to tell an electrician or the utility: "I did
this and this is what I saw" than to just throw a bunch of unrelated
observations at them ("Well, did you try *this*?" "No, but I tried
something (totally unrelated)!")
We had a neighbor around the corner have his metercenter catch fire!
Faulty connection on one of the mains and it just arced it's way into
flames. Likewise, had a vault "explode" (coincidentally, near that
I.e., when things start deviating from normal by too much, Bad Things
happen. "You have been warned" ;-)
of the AC. Then with almost everything cut off, plug in a large load such
as a bathroom heat or hair dryer to one side. If the unloaded side changes
voltage it is almost sure to be a neutral problem somewhere.
YOu can do this in the workshop, then move to the house.
If workshop and not house, it is probably your problem, if also at the house
and on the main wires, if the neutral is not loose at the box, probably the
power company problem
On Mon, 28 Dec 2015 18:51:14 -0500, "Ralph Mowery"
Generally speaking, checking at the service disconnect is about as far
as you can go because everything on the line side of that is sealed by
the PoCo. They will generally fix anything on that side for free, just
to keep you out of the metering equipment. Obviously if they determine
it is on the line side of the service point (typically the crimps on
the drop or the transformer connection on a service lateral), it is
their baby anyway.
On 12/28/2015 5:56 PM, email@example.com wrote:
the outlets in the house and they all read in the 122v range. I then
opened the house breaker box and both sides coming in read 122.7v. I
also checked the voltage coming out of the breaker that goes to the shop
and they also read 122.7. I also tightened all three wires down that go
to the shop (actually none were loose). I THINK that this tells me that
the problem is in the shop but we are currently in the middle of a
rain/sleet/snow storm here in the Midwest so I am no going back out to
the shop to look in that box again tonight. In fact, we were totally
without power part of this afternoon...the ice probably took a limb down
over a line.
Thanks for all of the help and let me know if you agree that the problem
is in the shop.
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