# sub electric panel, 100 amp

On my sub electric panel, 100 amp I have 154 volts on one leg, 85 volts on another and 35 volts on the neutral, what wrong. All the neutrals and grounds are connected to the same strip.
August 19 2009 - US
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Toan, maybe you could consider posting a panel "primer" as a new discussion to share information about that subject. It is obvious that you want to help and have good information, but a new thread about this subject might allow even more people in your area (and others) to read your post.
September 19 2011
• Contributions:139
You may have resolved your issue, however, if not then the following information may be helpful.  With any electrical diagnostic or repair, I will first recommend you seek out the services of a professional.  Considering the power company only supplies 120v per leg, leads me to believe you have an "open neutral" in one or possibly two of the circuits originating out of the sub-panel. Without testing, it will be tough to diagnose but i will give you a few things to try to help eliminate some variables. First of all you want to go to the main panel and test the voltage supplying the main panel. Then locate the breaker for the sub-panel. Check the voltage on the screw terminals of that breaker. If you still have uneven voltage then start turning off circuits in your sub-panel  until your voltage returns to 120v per leg. Once you know what circuit is causing this you need to check every device on this circuit for a loose neutral connection.
When you have an open neutral the devices still need the same power to run. Since the neutral wire might be compromised somewhere, the voltage usually travels from the other leg of the panel on the neutral wire. If you do the math all the voltage is there. 85+35=120 and 154-35=119
September 19 2011
By the way, this thread is well over 1 year old, so even though we are answering, the question was resolved a LONG LONG time ago, and none of the answers starting in February were of any value to the original poster.

And as I stated before, the person obviously knows how to use a meter and other tools, and has obvious experience working with electricity, and a home owner is allowed to do construction work on their own home, wood frame, up to 2 stories.  But it appears this person started work without a permit and wanted to skip the permit.

Telling a qualified owner builder that they have to have a licensed electrician to tighten down a few wire connections and to install a missing ground bus (if it really was missing), and remove a bonding jumper (if it really was installed) is disingenuous at best.

Especially when you post it needs to be done "soon" 6 months after the fact!

No, it will usually not burn the house down, but it will usually end up burning up power supplies, motors, lamps, ballasts, and tripping a circuit breaker.  And anyone that noticed that their 120 volts was 154 volts already knows they have a problem and they already shut it off!  No, it will not "kill them".  It is not like the guy decided to go and work on a 12 KV line while energized with no protection and no experience.

And no, it doesn't sound like a new sub-panel is needed; it sounds like it was already installed, but a couple minor details were missed that the building inspector would have caught.
September 30 2010
@oblb1

Are you new to Zillow? We don't have a Zillow Electrician Marketplace?
September 30 2010
I agree. It is also important for people to make sure that any contractor or subcontractor that they hire is licensed. Many states like CA have license information available online for consumers here
September 30 2010
• Contributions:29
Yes, it's always a good to use a certified electrician.
September 30 2010
• Contributions:5
Sounds like a new sub panel, with a certified electrician?

This is a great to have in zxillow, ask specific repairs questions? and have specific repair people pay for leads.....There is a bone, lets see who will bite it and make \$\$\$
September 30 2010
And, Priority Elect is right, the ONLY place the neutral is to be connect to ground is at the meter service, or a transformer.  If you don't have a separate neutral bus in your sub-panel, you need to add that, and make sure it is not electrically connected to the can.  Make sure your panel states that it is rated for 120/240 volts, not just 240 volts.

I'm assuming that your sub panel was installed per code and that someone inspected it at the time of installation, and that you were referring to a common bus at the meter panel; but it wouldn't be the first time something was installed without permit or inspection if your sub panel is missing the neutral bus.  (Actually, if you buy from a building supply store, they sell it with the neutral bus bar and ground jumper and are missing the ground bus, so you just add the ground bus and remove the jumper off the neutral).  I've even seen many licensed electricians make this mistake, so licensing by itself is no guarantee that it will be right.

Another common place for loose neutral connections is wire-nuts; often in a junction box or pull box under a house.  You think you have all the wires in the nut when tightening, but one is just not in there at all.
September 29 2010
It is simply a loose neutral connection.  Tighten it down at each location and the problem will be resolved.  It is "floating"; and because you have more load on one leg than the other, it is "pulling" the floating neutral one direction.

By the way, if you have aluminum conductors, you will need to use an oxidation inhibitor, or a high press fitting.  Aluminum Oxide is an "insulator", meaning it doesn't conduct electricity.  Ask at your building supply store or your electric supply store.

You can easily fix it yourself; just make sure you turn the power off before playing with the wires, and that you check it with a meter before turning it back on.
September 29 2010
• Contributions:3
It sounds like you have a serious issue with your nuetral leads with the sub panel. Let me be one more voice, you need to have a lic. electrician look at it ASAP. I erge this because of how dangerous the problem could be.
September 27 2010
• Contributions:7
The neutrals and grounds should not be tied togather at a sub panel they should be isolated from each other. Thats besides the point that you need a licensed electrician soon!!!
February 12 2010
• Contributions:16
I am a bit taken that you haven't called an electrician to come to your home and fix it right away.
With 154 volts going to some items in your home you are risking burning down your home.
There are several reasons that it may be happening.
Especially a loose neutral wire.
I do not suggest you go play electrician and get yourself killed.
I highly recommend you hire a qualified electrician ASAP
Normally I suggest checking out the electrician with the state board prior to calling but in your case I do no suggest you even use your computer in your house as you may cause damage or risk of fire to it and many other items in your home.
February 11 2010
You have a lose neutral wire.
December 05 2009
• Contributions:14
how you check voltage on neutral ? neutral to ground ? try with another tester or change battery at your tester.
September 01 2009
you may have a nail or screw in the wire feeding the sub.
check voltage at main panel and the brkr that feeds the sub.
do you have a 3 or 4 wire system in main panel?
August 19 2009

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