hi, i was at a friends for xmas dinner, he said he was having problems
with the stove. it wouldnt heat up.
and when you turned the oven dial up from 100 to 500 the kitchen
lighting would get brighter ??
the kitchen is on the left side of the house.all power on the sid eof
the house is acting wierd.
power on the right side seems to be fine.
i think that there is only 110 v coming into the panel, and the other
110v leg is dead. does this sound right?
we did not have a meter to check. the main breaker seems to be fine the
panel is fairly new not more than 10 years old.
it is in an industrial building, so we cannot acess the mechanical room
yet,but i think there will be a fused discconect switch in there.
am i on the right track??
A bad neutral connection is usually the suspect with symptoms like that.
Could be a bad hot, but less likely. Certainly something is amiss and
most everything should be turned off until the problem is isolated and
Not impossible, but not likely given the symptoms. Usually when 240V
appliances are having that kind of effect on unrelated circuits and the
other circuits are not out entirely it's a problem with an open neutral.
With all 240V appliances off, if it was an open hot leg all the circuits
on that leg would be dead.
With an open neutral and 240V appliances off, the 120V appliances on
each leg attempt to balance out the voltage between then (a complex and
changing series - parallel arrangement) and you will get localized over
and under voltage conditions depending on the balance of what is on at
the time. Turning on 240V appliances tends to have fairly dramatic
effects since they bridge both hot legs and tend to be significant
This can be a dangerous situation both to appliances and to people. The
low voltage conditions can damage appliances with motors like
refrigerators and the high voltage conditions can of course damage many
appliances and can present shock hazards in some cases. Items expecting
to see 120V can end up seeing close to 240V depending on how loads
balance. Fortunately more and more electronic items are 120/240V auto
ranging so they are less likely to be damaged, that still won't save
your fridge compressor stalled out trying to run on 80V though.
Since you mention it's an industrial building, I'm suspecting something
like an old mill condo conversion? If so, this condition does warrant an
emergency call to building management / maintenance.
Could someone explain how an increase of current on a 240 volt circuit can
change the neutral? This would be the result of one of the 120 volt
circuits having a heavy load with a leaking neutral. One side would have low
voltage and the other side would have high voltage because the neutral is
"pulled" to one side.
How about: by affecting control circuitry, which may well be 120v?
Besides, with the totally random set of loads possible, all sorts of
can happen. BTDT. Meanwhile, disconnect all loads possible until
situation is rectified.
Regardless, overarching problems first, and an open neutral is a very
Considered in isolation can understand the question. But; because there
are likely to be other 120 volt loads connected between the neutral and
either leg of the incoming supply. Also possibly other customers also
fed from that same centre tapped distribution transformer.
If the neutral is open (or high resistance etc.) the voltage on one or
both of the 120 volt legs could be floating around at weird voltages?
Also some cooking appliance do use the neutral to power 120 volt timing
clocks and other control circuits. The one thing in this house that
doesn't use the neutral at all is the electric hot water heater tank.
Every other 230 volt appliance has the neutral extended to it.
Sounds like a bad neutral to me, too. You can burn up stuff with this
The power company will check their end for free. Call them now.
You should check the connections in the panel when the power company
has the meter pulled.
This sounds like a problem for the guy with the mechanical room key.
This is a big warning sign! Draw more power/current and lights brighten
rather than dim? Big warning sign of a big "open neutral" problem!
The problem is big - it can result in 120V appliances getting a lot more
than 120V. Some 120V appliances have some significant chance of catching
fire before blowing a fuse at "just the wrong voltage" higher than 120 but
lower than 240.
The solution is to know where your main panel and any subpanels are,
open the doors and identify the neutral bus in each of these items, and
grab a plastic-handle screwdriver and take it to the screws on the
"neutral bus" and see if any of them are easy to screw in a tightening
direction (clockwise), and make any loose ones
"thumb-and-index-finger-tight" (or tighter than that if your fingers/hands
are on the weak side).
If that does not solve the problem or if you are not up to this, then
call in an electrician.
If the problem should end up being upstream of your electric meter,
then in most jurisdictions you should be able to get the electrician bill
sent to your electric utility company.
- Don Klipstein ( firstname.lastname@example.org)
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.