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Perry401 06-01-2011 10:48 AM

Detatched Garage Wiring Methods
 
The recent post on detatched garage wiring has me wondering about a neighbor's situation. The house (and garage) were originally wired knob and tube. This included four #10 wires from the house to garage. The garage light is on a 3-way switch with the second switch in the house. An outlet in the garage is hot all the time. Nothing is grounded of course. About half way between the garage and house is a tree which has grown up with branches which now are deflecting the overhead #10 wires. A previous owner had knob and tube knobs put in the tree to keep the wires from touching the large branches, but these are now becoming buried in the tree as it grows.

The home owner is perfectly happy with a 3-way switch and one outlet in the garage. They are concerned about the "tree wires" but don't really want to upgrade anything or spend any more than necessary. The wiring at the house was upgraded to a pair of UF cables, inside a plastic conduit and going to a weatherhead. Moving the wires on the garage end would not help the tree situation, but moving them about 10 feet on the house would eliminate the problem.

Any suggestions? The cheapest and easiest approach would be to install "new" knobs or similar insulators on the tree and leave everything else as is. The most costly arrangement would be to run new cable (perhaps buried), install a sub-panel in the garage, ground rod, etc. There are many scenarios between these two options.

J. V. 06-01-2011 11:24 AM

Pick any compliant option EXCEPT allowing it to remain the way it is.
My mother in Law had the same situation. When I found it, I disconnected the over head and pulled it all down. She has no power out there anymore.

jamiedolan 06-01-2011 11:24 AM

Quote:

Originally Posted by Perry401 (Post 659167)
The recent post on detatched garage wiring has me wondering about a neighbor's situation. The house (and garage) were originally wired knob and tube. This included four #10 wires from the house to garage. The garage light is on a 3-way switch with the second switch in the house. An outlet in the garage is hot all the time. Nothing is grounded of course. About half way between the garage and house is a tree which has grown up with branches which now are deflecting the overhead #10 wires. A previous owner had knob and tube knobs put in the tree to keep the wires from touching the large branches, but these are now becoming buried in the tree as it grows.

The home owner is perfectly happy with a 3-way switch and one outlet in the garage. They are concerned about the "tree wires" but don't really want to upgrade anything or spend any more than necessary. The wiring at the house was upgraded to a pair of UF cables, inside a plastic conduit and going to a weatherhead. Moving the wires on the garage end would not help the tree situation, but moving them about 10 feet on the house would eliminate the problem.

Any suggestions? The cheapest and easiest approach would be to install "new" knobs or similar insulators on the tree and leave everything else as is. The most costly arrangement would be to run new cable (perhaps buried), install a sub-panel in the garage, ground rod, etc. There are many scenarios between these two options.

There is only one good answer.

Install PVC conduit and pull wires (or use UF if you don't care about the switch loop). A basic sub-panel is cheap, I'm not even sure you need to have one, I think you can bring out a single or MWBC to the garage without a sub in the garage.

For the sake of their safety and for the sake of the tree, go underground.

WillK 06-01-2011 01:22 PM

A suggestion I'm unsure of comes to mind, hopefully others will weigh in - Perhaps the safety of the setup could be improved by GFCI... Then again, while I know I've seen GFCI on an ungrounded system discussed, I don't recall the outcome. The point is that it might be an improvement with minimal cost and effort.

I wouldn't suggest anyone run with the idea unless somebody smarter than me weighs in. For all I know this might not be a good idea after all.

WillK 06-01-2011 01:26 PM

Quote:

Originally Posted by jamiedolan (Post 659184)
There is only one good answer.

Install PVC conduit and pull wires (or use UF if you don't care about the switch loop). A basic sub-panel is cheap, I'm not even sure you need to have one, I think you can bring out a single or MWBC to the garage without a sub in the garage.

For the sake of their safety and for the sake of the tree, go underground.


This all being on one circuit, a subpanel shouldn't be needed, but conduit from box to box and THWN spliced to NM inside the junction boxes might be a solution.. It is a means of providing the travellers for the 3-way, and it works out less costly than UF. A TR GFCI in the garage wiould be prudent.

Odds are that if you're hitting tree branches in the air, you'll hit tree roots in the ground. There-in lies the biggest portion of the work for such a project.

dmxtothemax 06-01-2011 05:19 PM

Do you want the safest option ?
Or the cheapest option ?
New underground would be safest,
But cheapest would be new knobs on tree.
Personally I would lean towards underground.


Quote:

Originally Posted by Perry401 (Post 659167)
The recent post on detatched garage wiring has me wondering about a neighbor's situation. The house (and garage) were originally wired knob and tube. This included four #10 wires from the house to garage. The garage light is on a 3-way switch with the second switch in the house. An outlet in the garage is hot all the time. Nothing is grounded of course. About half way between the garage and house is a tree which has grown up with branches which now are deflecting the overhead #10 wires. A previous owner had knob and tube knobs put in the tree to keep the wires from touching the large branches, but these are now becoming buried in the tree as it grows.

The home owner is perfectly happy with a 3-way switch and one outlet in the garage. They are concerned about the "tree wires" but don't really want to upgrade anything or spend any more than necessary. The wiring at the house was upgraded to a pair of UF cables, inside a plastic conduit and going to a weatherhead. Moving the wires on the garage end would not help the tree situation, but moving them about 10 feet on the house would eliminate the problem.

Any suggestions? The cheapest and easiest approach would be to install "new" knobs or similar insulators on the tree and leave everything else as is. The most costly arrangement would be to run new cable (perhaps buried), install a sub-panel in the garage, ground rod, etc. There are many scenarios between these two options.


Perry401 06-01-2011 05:49 PM

Quote:

Originally Posted by jamiedolan (Post 659184)
There is only one good answer.

Install PVC conduit and pull wires (or use UF if you don't care about the switch loop). A basic sub-panel is cheap, I'm not even sure you need to have one, I think you can bring out a single or MWBC to the garage without a sub in the garage.

For the sake of their safety and for the sake of the tree, go underground.

Wouldn't it be possible to run 2 UF cables? One 12-2 w/ground for the outlet, one 12-3 w/ground for the light circuit. Protecting the larger tree roots should not be as hard using UF cable and an all hand-dug trench, as long as the trench can weave around a little as needed to miss roots or tunnel under them. I expect a more or less direct run from the house to the garage would be appropriate.

The home owner want's to do as much "himself" as possible. He has access to "volunteer" labor being the coach of the local highschool football team, so a hand-dug trench will only cost him a case of Gatoraide and some hot dogs and chips. I think laying a pair of UF cables would be easier for this home owner than trying to dig straight runs for PVC conduit.

When he is ready to start -- perhaps as early as next weekend -- he has agreed to get a permit for the job. I will help as much as I can (but not as "volunteer" labor, thank you.) I will need to draw up a plan view of the lot, house and garage location with proposed trench location, wiring diagram, materials list, and estimate of cost to take to the country to get the permit. Most home owners would not even know how to start on something like this, and that is one reason permits are often not pulled.

One jurisdiction I used to live in actually had a consumer advocate who would walk people thorugh the permit process, help them prepare documents, etc. But times are hard and there is no such service in the county where I now live.

WillK 06-01-2011 07:24 PM

See if you are able to locate 12-3 UF before you count on it. I never went as far as trying the electric supply stores, but HD did not carry 12-3 or 14-3 UF cable. Or wait... maybe it was that they had 12-3, but I would've had to get a 250' roll for $160 when all I needed was a 50' run (probably more like 45, but I wanted extra) Since I already had conduit in place, I was able to use a 50' spool of red THWN and a 100' spool of black THWN to get my 3 conductors (conduit used as ground since it is metal). My cost for the 2 spools: $33.

With PVC conduit, you'd add another $11 for a green spool and $20-ish for conduit... $60-$70 vs. $160 is quite a difference.

I suggest you price it both ways before you decide. PVC conduit will be a little forgiving of not being perfectly straight.

And for reference I used 2 teenage nephews to dig my trench.

dkeith 06-01-2011 07:37 PM

Remember to consider how you are going to get into the garage once you have the trench dug. I went through the concrete footing and slab floor, and then filled it in with concrete. I could have gone up the side and through the wall, but I am glad we spent the extra effort to make it cleaner.

Since we were going to the trouble, I ran 4 conduits - 2 large and 2 small - for possible future use, and capped the unused ends to keep critters out of the house.

It cost me ~$600 in labor (from a contractor who was already working on another project) and a trivial amount in materials just for the trench and conduits. Actual electrical work was extra.

vsheetz 06-01-2011 09:00 PM

Do it right and get it underground - IMO. The material cost is not that much. I would suggest wires in conduit. The hardest and most expensive part of teh job is digging the trench, which is covered by the 'volunteer' labor.


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