You have determined that it is in the neutral in the feeder. It might
even be worth disconnecting it AFTER YOU TRIP THE BREAKER for that
feeder and examine both ends of the wire for corrosion etc.
Then examine the lug and reinstall it.
I also did not notice a ground rod connection at the shop end. If you
are setting the "way back" machine to a time when 3 wire feeders to
additional buildings, you were still required to drive a rod. With
that much of a voltage drop in your neutral, you are putting voltage
on the case of all of your equipment.
A ground electrode will mitigate that a bit.
If you really want to address the violations you can also separate the
wires on the ground bus (one for each screw) you have plenty of
spares. You can double or triple up the grounds in most panels but not
the neutrals. They need their own screw.
What size wire is that feeder?
On 12/28/2015 7:14 PM, firstname.lastname@example.org wrote:
Okay, the feeder wire is #2 if I am reading the writing on the wire
I shut all of the power down and loosened the neutral in the main box in
the house and then reset it and tightened it up very tight. It did not
appear to be loose or corroded before or after I did this. I also
checked once again that the the hots coming out of the 100 amp breaker
in the main box in the house were tight and they were.
Now to the box in the shop. I attempted to tighten the hots but they
were already as tight as they would go. I then loosened the neutral,
checked for corrosion (there was none) and re-tightened it.
After doing the above I checked the voltages again and had the same 125
and 117 as I originally did so no joy.
Then I shut all of the breakers off in the shop panel including the main
100 amp breaker and checked the voltages again. Now things had changed
and I had 122v and 120v!
To this layman it appears that it is just difference in the load on the
two legs that is making the difference but now that the difference is
down to two (2) volts I think that is close enough. I suppose that I
could move some of the load from one leg to the other and even things
out somewhat. Of course it would depend upon what was turned on at any
Thanks to all who helped,
If you have 2 volts difference with no load, and 18 volts with a
load, you DO have a neutral problem - The fact that the high side
comes down and the low side goes up with no load proves it HAS to be a
neutral problem. There is no other possibility. How long is the feed
from the main to the sub? What kind of cable did you use? How deep is
it burried? Is it direct burial cable or in a conduit? Is it running
under a driveway?
Something is still not adding up. Also, do you have a driven
ground??? If not, get one in there and test again.
On 12/29/2015 8:40 PM, email@example.com wrote:
8 volts difference, NOT 18 volts difference. I am guessing (not going
out and measure) that the distance from box to box is approximately
140'. All I can tell you about the cable is that it says "AWG 2 AL TYPE
VSE-2 60 MILS XLP INSULATED 500 VOLTS" and that it is black. It is
buried approximately 4' deep and is not under a driveway. I do not
believe there is a driven ground rod at the shop. I did just happen to
put an 8' one in about three weeks ago for a "long wire antenna" for
antique radios that I have and it was not fun.
I appreciate the advice but it has been working well for approximately
eight years so nothing new is going to happen in the near future. We
will be leaving state tomorrow for New Year's Eve parties, returning for
a short period and then going to Florida until the beginning of March.
During that period noting runs in the shop except the central propane
fired hot air heating system.
*Measure* the potential between the neutral in your (workshop) box
(or, at any free outlet) and this ground rod taking care NOT to short
them in the process.
How do you KNOW that? Do you have a record of these observations/measurements
that dates back to that time?? I.e., for all you know, this may be a
recent development... or, related to the current loading, etc.
<frown> Horses for courses. I tend to not like *leaving* a problem
for fear something I've failed to consider will bite me in the *ss
while I'm "away" from it!
Enjoy your trip!
You must have some fairly heavy load in there.
Yes, move some of the heavier loads to the opposite leg. Try to balance
them. If you have a clamp around amp meter, put it on each main wire.
Do you have a green wire coming from the house? If not, you should have
a ground rod, and I believe I read that anything over 100' should have
one anyhow. When weather allows, I'd put in two ground rods and connect
them with #6 bare copper wire.
On Tuesday, December 29, 2015 at 8:53:00 PM UTC-5, IGot2P wrote:
What you're seeing is the symptom of a bad, partially functional neutral.
With no load, the voltages measured between either leg and hot will be
equal. As soon as you apply an unequal load on the legs, then current
flows in the neutral and you see the voltages differ. The larger the load,
the greater the difference. Tell us the amps flowing, the voltages you
are measuring and we can tell you how large the resistance is that shouldn't
be there. If the resistance is large enough and the current high enough,
it's going to get hot, very hot. If you have a 5 volt drop and 100A,
that's 500W at the point of the bad connection. How lucky do you feel today?
And rebalancing loads is just covering up the problem. It's only
effective if the loads on each leg are equal and on at the same time.
How are you going to achieve that?
Like others have suggested, probably time to call an electrician.
You've isolated to you do not have an imbalance at one end of a wire and
do at the other end...that's pretty clear evidence it's in the feeder or
the connections there.
How did you run the feed line; possible you got a knick in insulation
and are seeing moisture shunting effect in a buried line?
Of course, as gfretwell says, make the simple connection check first.
And, of course, there's still the issues regarding shared commons and
grounds, building ground for the shop, etc., etc., ...
And, if you cut off everything inside that box and the imbalance doesn't
go away, you've proven it's in either the feeder itself or the
connections, not a large imbalance in load in the box (altho that's
pretty well proven already; you can just conclusively demonstrate it to
yourself if there's no load and still and imbalance it's gotta' be
either the feeder is damaged or the connections).
John, this is typical of this group. The posters want everyone else to do
their work for them, then they argue and don't follow the information given
and most times the result is never known. Follow along in the posts and you
will see the offenders...
Which only confirms what you were told a week ago by clare, gfretwell, trader, and I'm not sure
how many other people: you have a bad neutral connection.
Since you don't seem to understand how this works, or the level of danger involved, I
recommend you hire a qualified electrician to find and fix the problem ASAP before your
house burns down.
On Wed, 30 Dec 2015 12:15:58 -0800 (PST), Uncle Monster
The problem with your solution is the voltage at the "main" panel in
the house has no problem. He has a problem between the main and the
sub. Underszed feed (for the length) and inballanced load could
explain it. Otherwize he has a neutral problem.
On Wed, 30 Dec 2015 18:29:58 -0800 (PST), bob_villain
Yea, it should have been spelled Imbalance. I used to be a very good
speller in my younger days - last one standing in spelling bees, but
there are more words now, and I've let my spelling slip - and
generally don't use spell-check.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.