Go Back  DoItYourself.com Community Forums > Electrical, AC & DC. Electronic Equipment and Computers > Electrical - AC & DC
Reload this Page >

Circuit measures 120V each side but not 240V across - what's the problem?

Circuit measures 120V each side but not 240V across - what's the problem?

Reply

  #1  
Old 04-16-06, 10:10 AM
chiefobrien
Visiting Guest
Posts: n/a
Circuit measures 120V each side but not 240V across - what's the problem?

Hello--

I recently had floor sanders come in and redo my floors. They hooked their sander directly into my Federal Pacific breaker box. Whether this casused my problem, I don't know, but I do know that neither of my air conditioning units work anymore. The 240VAC to 24VAC transformer is only putting out 9VAC. Each leg of the 240VAC transformer measures 120VAC to ground, but the legs do not measure 240VAC across each other. Back to the box, I looked at the 2 pole breaker. I see 120VAC on each side to ground, but 0V across each other.

Any idea what is wrong? What might the floor sanders have done? I intend to get them back in to fix it, but it's so hot I want to figure it out now.

Thanks!
 
Sponsored Links
  #2  
Old 04-16-06, 10:42 AM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
You should not have let the floor guys get near your breakerr box. Get them back out and have them fix the problem. Better yet, have them send out an electrician (at theor expense) to fix the problem.

They either did not connect the wires back up properly or they knocked a wire loose.
 
  #3  
Old 04-16-06, 10:56 AM
bolide's Avatar
Member
Join Date: Jan 2006
Location: PA
Posts: 1,909
Originally Posted by chiefobrien
I looked at the 2 pole breaker. I see 120VAC on each side to ground, but 0V across each other.
Someone rearranged wires by removing them from breakers (or even rearranged breakers in the FP box) such that your two poles are now on the same leg. If you have any multiwire circuits like this, you have a worse fire hazard.


Get a real electrician. Get rid of the FP box entirely.
 

Last edited by bolide; 04-16-06 at 12:06 PM.
  #4  
Old 04-16-06, 11:10 AM
Member
Join Date: Oct 2004
Location: USA
Posts: 719
You may want to look at the link about Federal Pacific panels.
http://www.inspect-ny.com/fpe/fpepanel.htm
 
  #5  
Old 04-16-06, 04:00 PM
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 5,599
The breaker is installed in the wrong slot. It is installed so that both poles are on the same leg. It is very easy to do in a federal panel.
 
  #6  
Old 04-16-06, 05:19 PM
chiefobrien
Visiting Guest
Posts: n/a
Bingo! I got the nerve to open the panel and pull out the breaker and look at the schematic on the door panel. Both legs of the double breaker are stabbed into the same line! I put it back the way it was because, now that I found the problem, I sure am not going to be the one to fix it. I think he screwed up other breakers, and I want them to make it right.

Now, this presents 4 questions:
1) Why would the sanding company move breakers? He said he was going to "clip into" my 240V at the box to run the drum sander. Would the only way to do this be to remove breakers and grab the bus bar itself?

2) Am I right in "nicely" accusing them, as these blowers worked only a month ago when I tested them, and I can't fathom how else this happened?

3) Did having same phase 120V on my A/C units damage them?

4) Should I ask the sanding company to fix it, or should I demand that they let an electrician inspect the box since it obviously was tampered with incorrectly?

Thanks for all your help!
 
  #7  
Old 04-16-06, 05:32 PM
chiefobrien
Visiting Guest
Posts: n/a
Also ,thanks for the links on the Federal Panel. I've been warned before about it.

How much would it cost to get the panel replaced? It's a 200Amp panel. The wiring in it is a friggin mess anyways, with every technology of wire that has existed since 1925 going into it. I think it was installed in 1971. Don't have the money to replace it now, but I don't even know a ballpark for these things.
 
  #8  
Old 04-16-06, 06:37 PM
bolide's Avatar
Member
Join Date: Jan 2006
Location: PA
Posts: 1,909
> Both legs of the double breaker are stabbed into the same line!

Yep.


> 1) Why would the sanding company move breakers?

In an FP box? They probably fell out.


> He said he was going to "clip into" my 240V at the box to run the drum sander.

That's normal. Some guys actually carry their own breakers of the correct amperage.


> Would the only way to do this be to remove breakers and grab the bus bar itself?

No. That's a bad way, especially in an FP panel.


> 2) Am I right in "nicely" accusing them, as these blowers worked only
> a month ago when I tested them,
> and I can't fathom how else this happened?

I think yes.


> 3) Did having same phase 120V on my A/C units damage them?

Not in the least. It was completely invisible.


> 4) Should I ask the sanding company to fix it, or should I demand that
> they let an electrician inspect the box since it obviously was tampered with incorrectly?

An electrician. If they were competent for the task, it wouldn't be wrong now. So their personnel are disqualified.

Frankly, though, I'd decline such a job myself. There are too many other risks with an FP panel.

I used to add breakers to them, but no more.

If they don't get you an electrician, you get one and pay him enough that he'll go to court with you.
 
  #9  
Old 04-16-06, 06:56 PM
chiefobrien
Visiting Guest
Posts: n/a
Thanks Bolide. Can I ask where you are in PA? If you're an electrician and near Philly, I may give you a call.
 
  #10  
Old 04-16-06, 07:05 PM
bolide's Avatar
Member
Join Date: Jan 2006
Location: PA
Posts: 1,909
Sorry, Chief. Too far away. Never worked in the city of the first class and wouldn't know their special regulations. Even so, I cannot accept any such work where you heard of me solely from DIY forums.
I am not here for direct pecuniary interests - only to learn and share - not even to make a reputation.

I do appreciate the compliment. I'm sorry I can't help you out in person.
 
  #11  
Old 04-16-06, 07:17 PM
chiefobrien
Visiting Guest
Posts: n/a
Fortunately, I'm not in Philly itself. I'm actually in the burbs. Guess I'll find someone local to look at it. Still haven't paid for half the floor sanding, so I've got something to hold over them to pay the electrician.
 
  #12  
Old 04-16-06, 07:35 PM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
If you go back to the floor company, be prepared to either negotiate with them or stand youyr ground.

If you ask them to come back and fix it, they will likely do so, especially if you still owe them money. However, if you ask them to send an electrician, they might balk.

None of us here can make the decision for you, it's one you have to make.

If you are satisfied with the work they did on the floors, and if you plan on replacing the panel fairly soon (which I recommend) then letting them back to fic the problem may be the best answer. You know how it should be installed, and will know right away if they did it correctly.
 
  #13  
Old 04-16-06, 07:48 PM
chiefobrien
Visiting Guest
Posts: n/a
Problem is that I'm already negotiating with them over a floor installation they did that messed up. They did a glue-down teak parquet installation on my front porch (enclosed sun-room with concrete slab) that has now failed twice (popped boards). I'm already annoyed and trying to get them to try another approach. Now I have to add the electrician to the mix.

BTW--I have no clue which breaker the upstairs A/C system is on. Can't seem to find another double-stab breaker than doesn't have 240 across it. I think this call for an electrician.
 
  #14  
Old 04-16-06, 08:11 PM
chiefobrien
Visiting Guest
Posts: n/a
Here is my e-mail to the sanding guy.

I have a matter of some urgency that I am hoping we can address. I tested my air conditioning about 2 months ago (both upstairs and downstairs central system), and the blowers came on strong. This weekend, I went to turn on the system and neither would turn on. I started my debug with the basement unit and found that the 240V transformer inside the blower had 120V on each side, but not 240V across. I checked the switch outside the unit and found the same thing. I traced the line back to the box and found the breaker was installed in the wrong spot. It's a double breaker, and both sides were stabbed into the same leg of the incoming power. They need to be on opposite legs to get 240V.

I couldn't figure out how this breaker could have moved during the month, but I remember that XXXX mentioned to me that he went to our basement and used 240V out of our breaker box for running the sander. I would like to know if it is possible that XXXX needed to remove some breakers to get power, or might have inadvertantly knocked them out and put them back wrong. I can't think of another way that this breaker could have hopped positions in the box.

As for the upstairs unit--I have the same readings on the transformer (as if it's getting both legs from the same phase), but I can't figure out which breaker is the problem. I haven't even looked at the power to the condensers (since it would be wired to the same area but to different breakers).

The whole box really needs to be looked at by an electrician at this point. As it is getting warmer, I want to get this fixed quickly and am trying to get an electrician out to fix it. I have had XXXXXX Electric do work in the past, and left a message with their answering service today. If you have an alternative licensed electrician that you work with who can come out quickly to evaluate the box and fix the wiring, please let me know. Otherwise, I will have XXXXX evaluate and repair the problem.
 
  #15  
Old 04-16-06, 08:23 PM
bolide's Avatar
Member
Join Date: Jan 2006
Location: PA
Posts: 1,909
> I have no clue which breaker the upstairs A/C system is on.

Meaning that the breakers no longer match up to the chart?

Do the A/C units share one transformer for their thermostats?


> Can't seem to find another double-pole breaker than doesn't have 240 across it.

There is one other possibility.

It would be that the A/C is turned on, but one stab is bent.

Turn the breaker OFF.
Take one wire off the breaker and cap it.
Turn the breaker ON.
Test for voltage on both poles (between each other and to ground as you did before).
Turn the breaker OFF.
Uncap and reconnect the wire.


You need a new floor company.
 
  #16  
Old 04-16-06, 08:40 PM
chiefobrien
Visiting Guest
Posts: n/a
> > I have no clue which breaker the upstairs A/C system is on.

> Meaning that the breakers no longer match up to the chart?

Meaning my house is 85 years old and the wiring is a mess. I'm in the process of mapping it, but it seems so darn random. One breaker turns off the lights in half the house, and some seem to do nothing. 3-wire outlets were added using external power wire runs for window unit A/Cs at one point, complicating the panel. There are 7 breakers for the basement, and 1 for most of the 2nd floor. As I said, it's confusing. But it all worked before they hooked in their sander.

> Do the A/C units share one transformer for their thermostats?

The 2 units are completely separate. One is in my attic and the other in the basement. They are Goodman units - 14SEER units with their own blowers and condensors (one 3 ton, the other 2 ton). In other words, one being knocked out has no bearing on the other.

> > Can't seem to find another double-pole breaker than doesn't have 240 across it.

> There is one other possibility.

> It would be that the A/C is turned on, but one stab is bent.

> Turn the breaker OFF.
> Take one wire off the breaker and cap it.
> Turn the breaker ON.
> Test for voltage on both poles (between each other and to > ground as you did before).
> Turn the breaker OFF.
>Uncap and reconnect the wire.

That might be so for the attic unit, but the basement one is most definitely installed wrong. I'm a DIYer, for both the personal interest and to save money. But this thing is such a mess I think I should let an electric company worry about it. My wife is so eager to get the air going. I said, "Honey, I can have this working in 5 minutes. But then it won't be exactly as the floor company left it and I won't have a case for having an electrician look over the whole thing".

BTW--are there any tools that might make eventually mapping my panel easier? Are these "plug in" things they sell at Home Depot for sniffing out a circuit worth it at all?
 
  #17  
Old 04-16-06, 08:45 PM
Member
Join Date: Aug 2005
Location: USA
Posts: 995
Originally Posted by chiefobrien
Are these "plug in" things they sell at Home Depot for sniffing out a circuit worth it at all?
Maybe. I bought the Ideal Circuit Breaker Identifier. Cost $50 and from a reputable manufacturer of many of my quality electrical tools. Well, it doesn't work at all. Adjusting the sensitivity takes it from beeping at every breaker to beeping at none of them. BUT, I have been led to believe that I might just have a lemon. Others claim to have good results with them.
 
  #18  
Old 04-17-06, 06:14 AM
chiefobrien
Visiting Guest
Posts: n/a
Here's an update. I spoke to the head of the company this morning. He said that they never remove breakers and that they always clip onto the line, so this can't possibly be his fault.

I had the cell phone number of the workman, so I gave him a call. He said they sometimes pop off a few breakers if they can't get onto the main, but he can't remember. Also, he was working with his son who might have done it and on and on. Basically, he wasn't sure what he had done.

The head of the company told me to get an electrician, but that he wasn't paying for it. Denies total responsibility. He says his guy is coming by this afternoon to look at it, but I have no clue what that even means. Arg--this is really frustrating. Thinking of getting the electrician, having him write up what he finds, and just withholding the funds from my final check with the bill from the electrician enclosed.
 
  #19  
Old 04-17-06, 06:20 AM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Be prepared to spend your own money on an electrician. While you might eventually get it back, be prepared for a fight. You may end up in small claims court.
 
  #20  
Old 04-17-06, 06:33 AM
chiefobrien
Visiting Guest
Posts: n/a
The electrician thinks it will cost about $95 to fix, since it will likely be less than an hour of work. My time in arguing this will cost more. My guess is that the flooring company thinks so too.

Of course, he'd have to take me to small claims court if I just withheld the money for the job from him, right?
 
  #21  
Old 04-17-06, 08:03 AM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
I don't know the answer to your question. If you signed a contract, he may be able to send a collection agency after you. But you can file negative reports with the better business bureau, etc.

Good luck.
 
  #22  
Old 04-17-06, 08:05 AM
chiefobrien
Visiting Guest
Posts: n/a
Oddly enough--he wrote a contract and e-mailed it to me, but started work without getting me to sign it. Does that mean he has no legal leg to stand on?
 
  #23  
Old 04-17-06, 09:46 AM
Member
Join Date: Oct 2004
Location: USA
Posts: 719
The electrician thinks it will cost about $95 to fix.
He thinks ?
What is he saying that the sanding people did to create your problem.
Without that being on paper you have nothing.
Do you need a new breaker, or just to move it over ?
 
  #24  
Old 04-17-06, 10:50 AM
chiefobrien
Visiting Guest
Posts: n/a
I told him that it looked like they had just pulled breakers and put them back in the wrong spots. He probably estimates <1 hour to fix at $95 an hour and he gets $95.
 
  #25  
Old 04-17-06, 11:26 AM
Member
Join Date: Oct 2005
Location: Milwaukee WI
Posts: 1,338
I had a similar issue when we bought our house. I specifically called the company and asked what kind of outlet they needed for the sander, like a NEMA configuration but of course they didn't know that and just said to talk to the guy when he got to the house. Well, I was swamped at work and had to do everything on the phone.

They ended up connecting directly to the bus with a receptacle that had alligator clips on the end of a pigtail. One day I came by after work and saw a big arc mark on the bus. There was nothing in the house at the time and I was going to replace the panel anyway so I didn't bring it up with them.

But next time I will do everything in writing: Request the configuration, tell them they may NOT connect directly to the bus. I wonder what OSHA says when somebody gets hurt doing this? It must happen frequently.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'