Off Topic - RV Workshop Electrical Power

tx_jayhawk · #1 08-16-2007, 08:51 PM

Sorry for the off-topic post, but I have an issue that has been bothering me for some time that doesn't make much sense.

I have developed an electrical power problem with the RV workshop. Mysteriously, I will just lose power at times to all of the outlets on a particular circuit (lately is has been off continuously). The breaker doea NOT pop, and I have inspected all outlets to make sure the wiring looks OK. It does not seem to be related to any particular event (doesn't go out when a device turns on, etc.), and I can't see any reason why this is happening. I have cycled all breakers in the panel, and nothing changed.

I thought there may be some electricians in the group that might be able to assist...any thoughts? Do breakers every "fail" in this manner (don't provide power and don't pop)?

Next step is either ripping into the wall or calling an electrician (less money to build ariplane).

Thanks,
Scott
7A Finishing

airguy · #2 08-16-2007, 09:18 PM

Change the breaker first. I have had breakers that fail "closed" - they don't trip or give any indication that they have failed.

If that doesn't work, and the problem still occurs even with a new breaker in it's place, you need to determine whether you've lost your power, or your ground. If the ground is disconnected, you will still have no voltage differential across the outlet, and no power available - but voltage will still be present. Find another outlet on a different branch, and measure the voltage between the ground of that known good outlet, and the hot leg of the suspect branch circuit. If the suspect outlets go "dead" on you, and you still have voltage present on that branch (relative to a known good ground) then you have lost your ground for that branch. Much less likely than a breaker problem, but not unheard of.

3rd possibility - but not likely, I've only seen this happen twice. You may have one leg of your transformer feed into the house being intermittent. The main feed from your service transformer comes into the breaker box with three wires - one "neutral", and two hot, with the two hot wires being 180 degrees out of phase with each other. The voltage between either hot and the neutral will be 120 volts, the voltage between the two hots will be 240 volts. I have seen cases where a bad connection either in the transformer or in the panel causes an intermittent open on one hot leg - which means that any circuit using that hot leg for power will get nothing. In your breaker panel, roughly half the 120-volt circuits pull power from each leg - so if you are losing one entire leg, you should lose roughly half the outlets in your entire home. You may not notice this if your lights/TV/fridge etc happen to be on the "good" leg and stay running. If your shop is pulling a main feed separate from the house, it's possible this could be happening without you noticing any other power issues. The only way to be certain if this is the case is to measure the voltage between the two main hot leads coming into your panel when your "suspect" outlets go dead - if it's 120 and not 240, that's the culprit. Time to call the electric utility for that one, the problem is either in the meter or the transformer.

PaigeHoffart · #3 08-16-2007, 09:22 PM

Hmmm, If you're not comfortable working with live electrical circuits, you're probably better off calling an electrician. However, there is one thing to check first to avoid the 5 minute, $50 service call. Look around for GFCI outlets. If your shop is relatively new, it should be protected by GFCI. Any little bit of stray current flowing to ground will trip it. It doesn't reset by itself, so someone else in the house would have to be resetting it. Occasionally they have been known to be placed in strange places like utility rooms or outdoor outlets.

If it's not a GFCI, it's probably a bad connection, faulty circuit breaker, faulty outlet or damaged wire. The circuit breaker is probably the only thing that would be easy to find. If it's completely failed, you would have no voltage on the circuit breaker output terminal. If you want to check it yourself, be advised that there are large buss bars in the panel that carry hundreds of amps, one particularly bad move could cause the end of a probe or screwdriver tip to vaporize, or worse. I'm not trying to scare you to keep my union buddies employed, I've seen experienced guys get bit; complacency kills when working on live stuff. I also would recommend using a low tech device like a $2 neon tester; most modern voltmeters can give erroneous readings when working in a panel due to their high input impedance.

Finally, its more than an inconvenience, a bad connection will generate heat, and can provide an ignition source.

Whew, I'm beginning to feel like George, I think it's time to shut up

edit: It looks like I posted the same time as airguy. If you want to check for an open neutral, the easiest way is to measure between the hot leg and ground. You can pickup a handy little outlet tester at any home improvement store that will tell you if an outlet is wired properly, if you have an open ground, or open neutral.

Paige

Mark Burns · #4 08-16-2007, 09:27 PM

Quote:

Originally Posted by tx_jayhawk

Sorry for the off-topic post, but I have an issue that has been bothering me for some time that doesn't make much sense.
<clipped text>
Next step is either ripping into the wall or calling an electrician (less money to build ariplane).

Thanks,
Scott
7A Finishing

Don't start ripping into the wall just yet! I could be a lot of things.
I would start at the breaker panel. Do you know which breaker supplies power to the receptacles with the "issue". If not we need to find out.
You can check the breaker with voltmeter. Carefully remove the breaker box cover and you'll see black or red wires coming out of each breaker. By touching one lead of the meter to the ground or neutral buss (doesn't matter which buss, the ground buss will have green wires on it and the neutral buss should be mostly white wires) Then touch the other lead to the terminal of each breaker where the wire leaves it. This shoud show 110-125 volts with the breakers on.

It's very common for the terminal screws on the breakers to become loose.
Usually the lights will flicker when you have a loose connection. Do you have any lights on the circuit in question?

Let me wrap this up it's getting long. You either have a bad breaker or a loose wire, and you probably knew that already. It also could be the buss bar that the breaker plugs onto. Breakers get loose there and cause problems, especially the Square D brand.

It's very unlikey the problem is in a place where you will have to rip into a wall!

If you don't feel comfortable making these checks you may need to call an electrician or better yet a friend that is one.

>The two replys you got above were not there when I started this reply, so I have some duplication, but they both make very good points.

Hope I helped a little.

Mark

L.Adamson · #5 08-16-2007, 09:32 PM

In addition to the other ideas....

Check the "neutral" leg. It's the white wire from the particular circuit, that screws to the neutral bar along with a bunch of other white wires. A loose one will give intermittant problems as described.

L.Adamson

rleffler · #6 08-17-2007, 05:21 AM

Quote:

Originally Posted by PaigeHoffart

You can pickup a handy little outlet tester at any home improvement store that will tell you if an outlet is wired properly, if you have an open ground, or open neutral.

Paige

Paige hit the nail on the head.......

Determine the problem first. The outlet tester will safe you significant time and is easy to use if you're not comfortable with using a VOM.

Once you know what the issue is, then you can start troubleshooting.

Captain_John · #7 08-17-2007, 06:11 AM

No one has hit it yet.

You have an "open" somewhere in the circuit.

If you have described it correctly and I understand you correctly, you will need to remove all the plugs and check the terminations on the devices and ascertain that they are tight and not made poorly.

If it is not a device termination, the wire is compromised somewhere in the middle of a run.

It would NOT be a problem in the panel if there are plugs UPSTREAM of this one that remain live and are on the same circuit.

It is likely in the branch.

Good luck!

CJ

Mike S · #8 08-17-2007, 08:52 AM

Quote:

Originally Posted by Captain_John

No one has hit it yet.

You have an "open" somewhere in the circuit.

If you have described it correctly and I understand you correctly, you will need to remove all the plugs and check the terminations on the devices and ascertain that they are tight and not made poorly.

If it is not a device termination, the wire is compromised somewhere in the middle of a run.

It would NOT be a problem in the panel if there are plugs UPSTREAM of this one that remain live and are on the same circuit.

It is likely in the branch.

Good luck!

CJ

Other than a bad breaker or buss, this is the only thing that will cause it.

As others have said, start at the start,---buss, and follow the path until there is no more voltage----------then fix whatever it is you find.

Good luck

LettersFromFlyoverCountry · #9 08-17-2007, 09:15 AM

I have this same problem in my garage. You didn't say whether your workshop is in your house or what. In my case, it turns out the outlet is apparently on the same circuit as an outlet in the bathroom upstairs. The GFI in the outlet in the bathroom pops, and it kills the outlet in the garage too.

#10 08-17-2007, 09:19 AM

"I will just lose power at times to all of the outlets on a particular circuit (lately is has been off continuously).

Hello,

I just moved into a 9 year old house and had this problem in the livingroom with the outlets. I noticed that when I ran the vaccume that it would sometimes quit working and then start again...hmmmm.

Here was my fix:
I suspected right away that it was the screws loose holding the wires coming from 1 outletstringing to the next.. I WAS RIGHT..

I left the vaccume running (hi amps) and gently kicked each outlet with my foot.. as soon as I thumped the second outlet, I found the culprit...the vaccume cut off and back on..

I turned off the breaker to this circuit and then took the wallplate off of the outlet...

it is a wonder the house had not burned down from this

The outlet box and the wall were burnt badly.. I would believe that this has been this way since the house was built 9 years ago..

I cut the wire back and replaced the outlet...All is OK..

Thats MY story!!! I hope you find the problem...good luck

Tom