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Forum topic by TraylorPark posted 12-29-2014 06:53 PM 1715 views 0 times favorited 38 replies Add to Favorites Watch
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TraylorPark

151 posts in 1058 days


12-29-2014 06:53 PM

Topic tags/keywords: electrical question

I’ve got an electrical question for those smarter than I. I have what I assume is a break in one of the hot wires that leads to my shop. The wire is 3-3-3 aluminum and directly buried. The run from the main panel in the house to the shop is about 200 feet. Anyway one of the post in the sub panel in the shop doesn’t really work at all and when I use things for too long in the shop the breaker in the house main panel trips but not the breaker in the sub panel. My plan for the summer when the ground is drier and I have tucked away some funds is to run new wire to the shop. However, in the mean time I would like to be able to use power tools for longer than 15 min without having to walk back into the house and reset the breaker or risk fire by the breaker getting too hot. My solution, assuming there is a break in one of the hot wires, is to disconnect the broken wire from the main panel and the sub panel. Attach the good hot wire to a single pole 50 amp breaker in the main panel and into the sub panel as it is now. All of my tools are 120v and under 20 amps. The sub panel I have now would allow me to run 2 20 amp lines for plugs plus a 15 amp line for lighting. So my question is: is there any reason why I couldn’t run the sub panel with only one hot wire?

Thanks in advance for any insight or knowledge you can pass along.

Zach

-- --Zach


38 replies so far

View TheFridge's profile

TheFridge

5764 posts in 946 days


#1 posted 12-29-2014 07:24 PM

Not that I know of. If your other hot and your neutral have no continuity between themselves and ground you should be good. And if there is no ground then make sure you land your ground and neutrals together in the panel and pull one when you pull the new wires.

This will work but it’s at your own risk. The main problem is not having a ground but I think you can drive 2 ground rods 10’ apart, run it to a ground bus, and it would be a start. You have to do it anyway when you pull the new wire.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View bigblockyeti's profile

bigblockyeti

3665 posts in 1180 days


#2 posted 12-29-2014 07:46 PM

You would have the potential for pulling a lot of current off one leg which isn’t necessarily a bad thing from a safety standpoint, but it’s good practice to try to have your loads balanced from both legs.

View Bluepine38's profile

Bluepine38

3341 posts in 2545 days


#3 posted 12-29-2014 08:01 PM

Check the screws that clamp the wires in the electrical panel on both the main and sub panel. Some times
people forget to coat aluminum wires with an anti-oxidant coating, or forget to tighten the screws properly.
If this is the case, remember to shut the power off before fixing the problem. If this is not the problem, I
guess you will have to wait for summer.

-- As ever, Gus-the 77 yr young apprentice carpenter

View bold1's profile

bold1

261 posts in 1307 days


#4 posted 12-29-2014 08:04 PM

Before you dig up your yard. Put a load on right at the breaker that’s tripping. You might have a breaker that is bad on one leg. Also check that the wires are tight in the breaker. A lot easier to replace that than the wire if that’s where the problem is.

View Fresch's profile

Fresch

34 posts in 1381 days


#5 posted 12-29-2014 08:06 PM

Is there any spliced cables?
Did you turn off the power and re tighten the connections at the breakers?
Did you take a voltage reading at the house breaker feeding your shop?
Did you take a voltage reading at the shop breaker and buss?

Splice, could be bad.
Connections on breakers could be loose. Type of wire copper, aluminum ?
House breaker could be bad, ( what brand ).
At shop if feeder is on a breaker could be loose or bad. Check potential on buss and breaker.
Get back with more info.

View TheFridge's profile

TheFridge

5764 posts in 946 days


#6 posted 12-29-2014 09:12 PM



Before you dig up your yard. Put a load on right at the breaker that s tripping. You might have a breaker that is bad on one leg. Also check that the wires are tight in the breaker. A lot easier to replace that than the wire if that s where the problem is.

- bold1

Forgot about that.

If the wire is loose at the breaker it’ll heat up and trip. Or kill the breaker. Never hurts to pull an amp reading either to double check. Sounds like the breaker is bad.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Tennessee's profile

Tennessee

2410 posts in 1974 days


#7 posted 12-29-2014 09:35 PM

I am where Gus and The Fridge are. The chances of actually losing a leg is low. A connection on the other hand, the chances are high.
1. Bad connection. Aluminum has one of the largest expansion/contraction percentages in electricity, and can walk a screw right away from a breaker.
2. Bad breaker. If you had an unbalanced load over time, you could have lost a breaker.

Somehow, I doubt it is the wire. As a maintenance engineer for over 28 years, you learn that it almost ALWAYS is at the connection, not the run…
One exception – if you have a connection in the run.

-- Paul, Tennessee, http://www.tsunamiguitars.com

View BoardSMITH's profile

BoardSMITH

121 posts in 1723 days


#8 posted 12-29-2014 09:48 PM

Call an electrician and get things done right by a real professional. Trouble shooting from a forum entry is not the best way to solve a problem.

-- David www.TheBoardSMITH.com

View TheFridge's profile

TheFridge

5764 posts in 946 days


#9 posted 12-30-2014 12:04 AM

Ehh. If you don’t have the money this is a great place to start.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View WhyMe's profile

WhyMe

610 posts in 1021 days


#10 posted 12-30-2014 12:22 AM

If the feeder is old and is aluminum and direct bury for 200 ft. I’ll bet there was a nick in the insulation and the aluminum has has turned to crud. How old is this feeder? It’s fine to use the good leg to just get 120V until replaced. You can still use the DP breaker you have just disconnect the bad leg. If the current feeder is only 3 conductors it needs to be replaced with 4 conductors. There needs to be an equipment ground that goes back to the main service panel. The neutral(s) at the sub-panel in the shop need to be isolated from the ground(s).

Also here’s a better forum to get electrical info.
http://www.garagejournal.com/forum/forumdisplay.php?f=30

View TopamaxSurvivor's profile

TopamaxSurvivor

17654 posts in 3136 days


#11 posted 12-30-2014 03:01 AM

What brand is your main panel?

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View woodworkingdrew's profile

woodworkingdrew

189 posts in 1069 days


#12 posted 12-30-2014 03:17 AM

If the breaker is tripping that often you know there is a short or something is not wired correctly. There is a reason why electricians make good money to troubleshoot problems. I worked for an electrical contractor for 2 years. Your problem is way to advanced for you to be taking advice from amateurs in this forum. Call a licensed electrician before you either A. Start a fire, or B. Get electrocuted.

-- Andrew, California

View daddywoofdawg's profile

daddywoofdawg

1010 posts in 1035 days


#13 posted 12-30-2014 06:33 AM

have you checked your outlets and switches? I paid a pro because I was having a similar problem,he could find the problem,then one day I found out the outlet at the beginning of the run was bad I fixed it and been going every since.Moral of the story is it could be a cheap simple fix.Like when I repair a computer,I start at the on button to see if it turns on if no check to see if it’s plugged in if yes see if the outlet works,etc.

View TraylorPark's profile

TraylorPark

151 posts in 1058 days


#14 posted 12-30-2014 02:03 PM

Lots of good advice.

So here is what I did. I checked the breakers for any resistance, the main panel is Siemens by the way, and I found none. So I reconnected the feeder lines to the breaker in the main panel and tightened them good. I don’t have a torque screwdriver so I just made them tight. I did the same thing in the sub panel, checked all the breakers and tightened all the connections. I turned the power back on and started taking voltage readings. On the feeder wires coming out of the breaker or right at the breaker I was reading about 140V. Then I went out to the sub panel and took readings on the feeder lines and they were reading about 125V. So then I gave it a good test. I plugged in a bunch of lights to the circuit that normally blows the breaker in about 5 minutes and then I ran the table saw for a bit, then the RAS with the shop vac at the same time for a bit too. Nothing tripped and the breaker in the main panel was not warmed up at all. It was a short test, but very encouraging results.

Thanks for reminding me to keep it simple. I had checked all the breakers when I fist started having the issues, but for some reason never even thought to check the connection.

-- --Zach

View WhyMe's profile

WhyMe

610 posts in 1021 days


#15 posted 12-30-2014 05:00 PM



If the breaker is tripping that often you know there is a short or something is not wired correctly. There is a reason why electricians make good money to troubleshoot problems. I worked for an electrical contractor for 2 years. Your problem is way to advanced for you to be taking advice from amateurs in this forum. Call a licensed electrician before you either A. Start a fire, or B. Get electrocuted.

- woodworkingdrew

So what makes you think the advice is just coming from a bunch of amateurs?

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