240 was working now not... at a loss here

[timdhawk]

Hey guys. I'm in the final stages of my detached garage project (build thread forthcoming). I've had a 240v outlet powered in there for a couple weeks now for a heater which has been working just fine until last night.
I have a 100A sub panel off of my 200A house main. The only thing running in the garage is the heater.The breaker is not flipped and the heater works on another outlet in the house... just not in the garage.
I have a run of about 100 total ft or less of 2,2,2,4 direct bury cable. On the house side, each feed reads 119v to 120v. On the garage end one reads 120v but the other is only about 86v-88v...what's up with that? but yet, each wire on the heater outlet reads 120 but the heater doesn't run...

ideas?

 

[rockwithjason]

Open neutral or seriously bad connection somewhere.

 

[txvwnut]

That 86 to 88 volt reading makes me think you've lost the neutral. You can also loose one side of your main breaker, had that happen before, and it won't look tripped.

 

[timdhawk]

just checked the wires themselves. On the main side I have 118 and 121 as it comes out of the 100A breaker. On the sub panel side, 121 and now 24V ON THE WIRE as it connects to the main breaker... I don't understand what's happening.

If I've lost the neutral somewhere, will I see voltage on it? I should specify that I only have just the one 240 outlet even hooked up. Its only a 3 wire plug. The neutral wire isn't connected to anything.

 

[pattenp]

If you had a bad neutral you would have wacky voltage on both legs. Check the voltage across both legs at the main panel then at the sub-panel. You should see 240V. Sounds to me you may have a bad hot conductor underground. How long has the cable been buried? Also check the voltage from each leg to the ground at the sub-panel to see if you get the same low voltage on the one leg.

On a side note, 2-2-2-4 aluminum is only rated to 90A as a branch feeder. Assuming it's aluminum.



*

 

[timdhawk]

I've got 240v across the main and 145v across the sub, WTH?

 

[joe_padavano]

I've got 240v across the main and 145v across the sub, WTH?

You have a bad connection somewhere. I had a similar problem once that ended up being a bad crimp on one of the hot wires coming down from the transformer to the meter. The PoCo obviously had to fix that one, but the issue was the same - lower voltage.

 

[pattenp]

Have you verified that the wire connections are tight at the feeding breaker?

 

[larry_g]

I'm thinking that your feed is leaking like it was nicked during the burial process and now that the rains have come there is enough moisture in the ground to start carrying off voltage? I would also make sure that you are checking the voltage under load. If checking under load and you are at or near 0 volts then your finding a bad connection or broken wire.

Since you have 2,2,2,4 and are only using 240 volts you could try unhooking the hot wire, on each end, that is giving the problems and use the neutral as a replacement, FOR TESTING ONLY, and see if you have a good circuit again. If so then you have a wire problem in the buried wire. If your using 120 volts in the subpanel then do not do this.

lg
no neat sig line

 

[QuickRick]

Larry is absolutely right.

I would flick off all of the subpanel breakers in addition to substitution of the bad hot wire with the neutral wire for testing.

This will prove whether or not the low voltage side is due to that wire. It is a very simple and bulletproof test. Just test to the mains of the subpanel for 240 volts.

Is the wire spliced anywhere? Just curious and if so where?

QR

 

[wyliesdiesels]

Thats not a sign of a bad neutral.

Thats a sign of a dead hot leg.

Check for bad connections.

Since the cable is direct buried i bet it got damaged.

This is a good reason why conduit is used...

 

[OccupantRJ]

When you are checking power at the house end, are you checking it on the breaker's output lugs, or on the exposed part of the conductor itself? Also check for a nail that may be penetrating the power conductor on either end. I have seen this situation cause a voltage drop before. Had 78 volts on it.

 

[Slowgsr]

I agree that you have a burned/damaged conductor in the ground.

 

[timdhawk]

Weird. If i do have a bad conducter in the ground... why would i only now see this issue and not before? The heater had power was working just fine for almost 2 weeks then for no reason... this issue.

I think I'll try the neutral test mentioned above and then maybe call in an electrician to troubleshoot for peace of mind tomorrow...

 

[zmaxmotorsports]

If he lost the neutral the other leg shouldnt be showing 120v,Id start checking for loose connections.
Maybe try resetting the breaker in the house and start checking for power at that point out.

 

[Slowgsr]

It takes time for the conductor to burn once damaged, but sometimes not long.

I've pulled out burnt wires after 20years,

Your electrician will megger the cable to test insulation, I always to this to motors before calling it bad

It could be something different, sometimes it's hard to diagnose when given symptoms by a homeowner (no offence)

 

[timdhawk]

Well...****. looks like I have a bad conductor. I did the neutral conductor swap and I get 120 on both legs into the garage...

damn it! I was just finishing paint and getting ready to hang lights, take pics and start my own build thread... o well... time to rent a big power tool and start digging!!!

 

[larry_g]

I would suggest that you talk with a local electrical contractor and see if they have the tools to find an underground fault. If your talking a long run then it may be worth the trouble to fix it.

lg
no neat sig line

 

[QuickRick]

Well...****. looks like I have a bad conductor. I did
the neutral conductor swap and I get 120 on both legs into the garage...

damn it! I was just finishing paint and getting ready to hang lights, take pics and start my own build thread... o well... time to rent a big power tool and start digging!!!

I feel your pain, kind of a drag to have this happen. I did the direct burial route in 1987 and it held up fine all of these years.

QR

 

[zmaxmotorsports]

Thats why I like to bury everything in pipe.

 

[nsula_country]

I was going to suggest Megging the cable, but someone beat me to it! Also, you troubleshot and found a bad conductor.

This is a lesson in life as to why conduit is a wise idea. More upfront cost, but protects the wire and would make replacement easy, pull and play.

Since it was direct bury, did you have any earthworms dancing on top of the ground!

CT

 

[MikeF2316]

Make sure that both legs of the breaker are on. I've seen where ganged breakers were such that the one clicked on was holding the other in a position that wasn't quite on, but looked like it was.

 

[wyliesdiesels]

Thats why I like to bury everything in pipe.

Us sparkys on this board are constantly recommending to people to run their MHF through conduit underground but some feel that direct burying it will be fine.

This is an example of a good reason why underground feeders should be in conduit.

Make sure that both legs of the breaker are on. I've seen where ganged breakers were such that the one clicked on was holding the other in a position that wasn't quite on, but looked like it was.

In #4 he already tested the voltage on the load side of the feeding breaker and got acceptable readings.

 

[MikeF2316]

...


In #4 he already tested the voltage on the load side of the feeding breaker and got acceptable readings.

Ah, yes, when I read the thread the first time, I only remembered the crazy voltages he got which can be caused by back feeding from the good leg through the 240 volt load to the disconnected leg, then from there through the 120 volt loads to neutral. And no matter what, my "solution" doesn't cost anything.

 

[walrus]

While I agree conduit is the way to go, it doesn't mean you will be able to get old wire out or new wire in if original wire fails

 

[ezzzzzzz]

Well...****. looks like I have a bad conductor. I did the neutral conductor swap and I get 120 on both legs into the garage...

damn it! I was just finishing paint and getting ready to hang lights, take pics and start my own build thread... o well... time to rent a big power tool and start digging!!!

Did you swap it back and get the original results?

 

[nsula_country]

While I agree conduit is the way to go, it doesn't mean you will be able to get old wire out or new wire in if original wire fails

Not always, but the odds improve greatly in your favor!

CT

 

[ishiboo]

I would double-check all breakers and the connections/terminations themselves before you get too far. I think it's very unlikely there has been an issue this soon with direct buried cable, especially if it was installed correctly. (In a bed of sand or whatever if there were rocks present)

 

[Zeke]

Why would there be a buried connector? I think it's at one end or near the end.

 

[timdhawk]

Found the issue!!! Not sure how the hell it got compromised but this is the reult!! Old wire replaced with new!!! Digging up the old stuff REALLY sucked... but now I'm back in business. Thanx for all the help and suggestions...

PS - for the record that trench was redug for a straight shot out of the garage instead of whats in the picture.

 

[ishiboo]

Wow. Make sure that wasn't shorted to another conductor.

This is only a few weeks old?

 

[Zeke]

Tough earthworms in his part of the country.

 

[nsula_country]

Tough earthworms in his part of the country.

I suspected a damaged conductor. And I visioned earthworms Twerking on top of the ground with all that voltage in the soil.

Good find. One more reason conduit is a good idea.

CT

 

[CNGsaves]

DOCTOR'S WORM WARNING: If you've taken ****** and had electrical shock in nearby ground, you may experience an erection that lasts longer than 4 hours which will please all the momma worms, but MAY cause death !!

You should contact your worm doctor and discontinue use of ****** !! . . .

 

[pattenp]

Just the slightest nick in the insulation exposing the aluminum to water and minerals in the soil will destroy the aluminum in short order once the juice starts flowing into the ground. Unless I missed it, you never said how long ago the cable was buried.

 

[Slowgsr]

This is the reason why I love teck90 so much. Sometimes im too lazy or don't have time to bury conduit, and I won't buy garbage. Leaves teck as the answer

 

[timdhawk]

Just the slightest nick in the insulation exposing the aluminum to water and minerals in the soil will destroy the aluminum in short order once the juice starts flowing into the ground. Unless I missed it, you never said how long ago the cable was buried.

the cable was less than 2 months old...