Wiring subpanel with a passthrough?

[aczlan]

Looking at running a 10/3 out to the barn to replace the current 12/2. At the same time, I would like to add outlets in the detached garage (which is currently also serviced by a 12/2 wire).
Can I go to the garage, run the wire into a breaker panel (thinking of a little 2 space 70 amp panel like: http://www.tractorbynet.com/forums/...533505-wiring-sub-panel-hom24l70s_detail1.jpg but wired for 220V) and run (without using a breaker) another line off of the main lugs to continue to the barn?

Would prefer to use a little panel as I will only have 1-2 circuits in the box and wont need a larger panel.

Aaron Z

 

[studor]

Check the electrical code where you are. In many cases the panel has a ground lug that has to be removed. Also make sure the wire dimension of the first leg is adequate for both load centres the 10/3 is too light for even the 70 amp panel and depending on distances you may also want to go thicker -- JMHO -- your code and electrician may vary.

 

[aczlan]

Check the electrical code where you are. In many cases the panel has a ground lug that has to be removed. Also make sure the wire dimension of the first leg is adequate for both load centres the 10/3 is too light for even the 70 amp panel and depending on distances you may also want to go thicker -- JMHO -- your code and electrician may vary.

Will make sure that the neutral and ground are separated in both boxes. That's why I am going to a 10/3 vs a 10/2.
The garage will have 1 or 2 20 amp circuits and a 15 amp lighting circuit. Oonly planning on doing battery charging, running a door opener, etc in there.
The barn will have 3-4 water heaters running in the winter (2-3 buckets and a tank heater) and I hope to have 2 20 amp outlet circuits and a 15 amp light circuit.

The garage is probbaly 75' as the wire runs from the panel and the barn is another 50 feet from the garage.

Aaron Z

 

[magicheater]

I have thought about the same thing. I have a sub panel in the basement with an 8-3 feed. I plan to feed a garage off the sub panel with 8-3 and use the same breaker in the main panel for protection. Neither of the panels will have a high current draw and the breaker in the main panel will be rated for the 8-3. Ground and neutral will be kept separate and only tied at the main panel. I have been corrected before, any one see any problems?

 

[Raspy]

The problem is you won't have a disconnect on the barn circuit that is within a reasonable distance. Your grounding might be a problem, and your total breaker amperage is limited to the breaker that feeds the your new wire.

It would be better to treat the garage as a sub panel, use your wires as feeders with a 30 amp breaker (10 gauge wire) and have a couple of breakers to feed the barn and garage circuits. You could carry the ground back to the main panel, or better yet, ground the sub panel in the garage.

 

[aczlan]

The problem is you won't have a disconnect on the barn circuit that is within a reasonable distance. Your grounding might be a problem, and your total breaker amperage is limited to the breaker that feeds the your new wire. It would be better to treat the garage as a sub panel, use your wires as feeders with a 30 amp breaker (10 gauge wire) and have a couple of breakers to feed the barn and garage circuits.

As I understand it, as long as I have less than 6 circuits in a subpanel, the breakers themselves serve as the disconnect. Here is that stated by MN: http://www.ci.bloomington.mn.us/handouts/53/53fffdetach.pdf . NY has similar rules.
I could go with a bigger panel, but I dont know that I will ever use more than 20 amps in the garage, so that would be way overkill.

You could carry the ground back to the main panel, or better yet, ground the sub panel in the garage.

There will be separate ground and neutral bars in the box and I will have 2 ground rods at each location that will also be tied into the ground that runs back to the main panel.

Aaron Z

 

[Tractor Seabee]

Looking at running a 10/3 out to the barn to replace the current 12/2. At the same time, I would like to add outlets in the detached garage (which is currently also serviced by a 12/2 wire).
Can I go to the garage, run the wire into a breaker panel (thinking of a little 2 space 70 amp panel like: http://www.tractorbynet.com/forums/...533505-wiring-sub-panel-hom24l70s_detail1.jpg but wired for 220V) and run (without using a breaker) another line off of the main lugs to continue to the barn?

Would prefer to use a little panel as I will only have 1-2 circuits in the box and wont need a larger panel.

Aaron Z

To properly design this there is more info needed. What is the total distance from your feeding panel to the futhest outlet/lights? Voltage drop may require larger wire than short runs do. #10 may become #8. What is the total connected load of all the heaters, plugs, and lights? You are probably a little short on your ampacity. First thing happens you want to run a saw or grinder out there , the lights and water heaters are on and whoops, breaker pops back at the house panel. Even small water heaters (10 GL) draw almost 20 amps, others on up are 30 A 220, that is your total capacity bthe way you have it.

Get one of those DYI electrical manuals at the big box store, (the DEWALT one is good) and do it right. Follow the instructions for proper grounding procedures. Are any of the buildings steel frame or skin? That has to be grounded at the panel also or the GFCIs won't work. Oh! you did not think of that safety matter.

I am planning on some of the same scenario for my greenhouse. It wll have lights and at least 3 20A circuits and a 30A heater, plus feed a couple other sheds for lights. I am running a #6 to that panel with a 50A two pole main breaker. My main fed out of the garage is a 2" PVC conduit, cheap insurance when I want to add or upgrade as more things develop over time.

Ron

 

[aczlan]

To properly design this there is more info needed. What is the total distance from your feeding panel to the futhest outlet/lights? Voltage drop may require larger wire than short runs do. #10 may become #8.

From the panel to the far end of the barn is probbaly 250 or 300 feet, but there wont be much load out there, 3 buckets and a few hundred watts of lights.

What is the total connected load of all the heaters, plugs, and lights? You are probably a little short on your ampacity. First thing happens you want to run a saw or grinder out there , the lights and water heaters are on and whoops, breaker pops back at the house panel. Even small water heaters (10 GL) draw almost 20 amps, others on up are 30 A 220, that is your total capacity bthe way you have it.

I may not have been clear on what the "heaters" are. These are to keep the buckets and water tank from freezing. The tank heater is 1250 watts (this one)and the buckets (these) are 150 or 200 watts each. For lights, there are 8 "floodlights" which each have a florescent floodlight in it (26 watts per bulb)
That all currently runs off of 20 amp circuit that is direct buried and is of questionable quality.

Get one of those DYI electrical manuals at the big box store, (the DEWALT one is good) and do it right. Follow the instructions for proper grounding procedures.

I used to work for an electrician and have worked on systems ranging from replacing a 60 amp fusebox to a business (tanning salon) that had 6 200 amp panels in it. Most anything you would find in that book (other than voltage drop over distance), I can do (my favorite was wiring a room that had 5 doors with 5 switches to control one set of lights, lots of 4 way switches).
Something like this wouldn't be in such a book, so I asked the TBN brain trust.

Are any of the buildings steel frame or skin? That has to be grounded at the panel also or the GFCIs won't work. Oh! you did not think of that safety matter.

Water+Electricity = GFCI. No two ways around it. A frozen tank is easier to deal with than a dead animal or person due to electric shock.
Being as the one metal wall of the barn has the electric fence running next to it, that will be grounded.

I am planning on some of the same scenario for my greenhouse. It wll have lights and at least 3 20A circuits and a 30A heater, plus feed a couple other sheds for lights. I am running a #6 to that panel with a 50A two pole main breaker. My main fed out of the garage is a 2" PVC conduit, cheap insurance when I want to add or upgrade as more things develop over time.

Sounds like fun. I will be running 2" out to the garage to allow for the wire for the generator that will eventually end up out there (connected to the main panel through its own set of wires and an interlock system to prevent backfeeding to the pole), but only 1" to the barn.

Aaron Z

 

[Tractor Seabee]

From the panel to the far end of the barn is probbaly 250 or 300 feet, but there wont be much load out there, 3 buckets and a few hundred watts of lights.

I may not have been clear on what the "heaters" are. These are to keep the buckets and water tank from freezing. The tank heater is 1250 watts (this one)and the buckets (these) are 150 or 200 watts each. For lights, there are 8 "floodlights" which each have a florescent floodlight in it (26 watts per bulb)
That all currently runs off of 20 amp circuit that is direct buried and is of questionable quality.


I used to work for an electrician and have worked on systems ranging from replacing a 60 amp fusebox to a business (tanning salon) that had 6 200 amp panels in it. Most anything you would find in that book (other than voltage drop over distance), I can do (my favorite was wiring a room that had 5 doors with 5 switches to control one set of lights, lots of 4 way switches).
Something like this wouldn't be in such a book, so I asked the TBN brain trust.


Water+Electricity = GFCI. No two ways around it. A frozen tank is easier to deal with than a dead animal or person due to electric shock.
Being as the one metal wall of the barn has the electric fence running next to it, that will be grounded.


Sounds like fun. I will be running 2" out to the garage to allow for the wire for the generator that will eventually end up out there (connected to the main panel through its own set of wires and an interlock system to prevent backfeeding to the pole), but only 1" to the barn.

Aaron Z

Sounds like you have it wire (no pun intended). Its just that we get so many posts from novices that we tend to treat all that way; sometimes. I have seen some dangerouus schemes posted due to pure lack of knowledge. DYI is rewardibg but can sure get you in a jackpot for the unwary. That is a long distance. Full voltage at the end probably means #8 or #6 for that 30A feeder. I put my Electricalc somewhere and cannot find it.

Ron

 

[aczlan]

Sounds like you have it wire (no pun intended). Its just that we get so many posts from novices that we tend to treat all that way; sometimes.

Been there, done that a time or two

I have seen some dangerouus schemes posted due to pure lack of knowledge. DYI is rewardibg but can sure get you in a jackpot for the unwary.

A little knowledge can be a dangerous thing...

That is a long distance. Full voltage at the end probably means #8 or #6 for that 30A feeder. I put my Electricalc somewhere and cannot find it.

As long as I can get 10 amps at the end, I should be fine. With 220 to the box in the barn, I plan to put the stock tank heater (~70 feet closer to the panel than the buckets) on one leg and the lighting/buckets on the other to balance the load somewhat.

Aaron Z