Outdoor Sub Panel

Reply

  #1  
Old 05-07-12, 06:50 AM
Member
Thread Starter
Join Date: May 2012
Location: usa
Posts: 8
Outdoor Sub Panel

Hello:
I am looking into installing a sub panel at my camp. The main box is 100amp service, the sub panel is going to be about 185 feet from the main box. I want to run either 6 gage or 8 gage wire to the sub panel. I will have a 50 amp breaker on the main and sub panel. I would like to a larger breaker on both ends if the sell it. I want the sub panel to have four circuits, two at 20 amp and two at 15 amp. The overall load should never exceed 45 amps. We run a air conditioner, refrigorator, some lights, and at times a couple crock pots. Coming out of the sub panel I will have 10/3 wire going to outlets, I pick the larger wire because it is another 100 feet from the sub panel to the outlets. Does this make sense and will this work?
 
Sponsored Links
  #2  
Old 05-07-12, 07:15 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,671
I want to run either 6 gage or 8 gage wire to the sub panel. I will have a 50 amp breaker on the main and sub panel.
For a 50a circuit at 185 feet #4 would be best. #6 might cause excessive voltage drop when the AC starts depending on other loads at the time. #8 is not code compliant for a 50 amp breaker at any distance. The size of the breaker at the subpanel can be larger then the supplying breaker since it only acts as a disconnect. If you get a main breaker 100 amp breaker panel kit it will come with a 100 amp main breaker and may be the cheapest route. Then you will only need to buy a ground bar.

Coming out of the sub panel I will have 10/3 wire going to outlets, I pick the larger wire because it is another 100 feet from the sub panel to the outlets. Does this make sense and will this work?
Why not put the subpanel closer?
 
  #3  
Old 05-07-12, 07:38 AM
Member
Thread Starter
Join Date: May 2012
Location: usa
Posts: 8
I would like to use #4 wire... but the cost is a lot at 185. Is there a big difference in voltage drop using #6 vs #4 at that distance. I want to put sub panel as close as possible to the camp using the larger wire. Isnt there less voltage drop using the larger wire than using a smaller wire. I could run mulitple lines out of main box using 10/3 but the voltage drop at 300 feet is a lot (i think you only get about 90) I want to have as much voltage and amps as possible at 300 feet from main box. Any suggestions?
 
  #4  
Old 05-07-12, 08:01 AM
Member
Thread Starter
Join Date: May 2012
Location: usa
Posts: 8
I am also looking at what type of wire to buy, is Cerro Wire 6 AWG 100' Stranded THHN Wire the right wire to use? This only has one line in it, do I have to run mulitiple lines of this for hot/neutral and ground? I am no electrian by any means!! I have to run this in ground, does that make a difference? I am going to use some kind of tubing to run it in. Does it have to be outdoor rated if I run it in a tube?
 
  #5  
Old 05-07-12, 08:07 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,671
You need two hots, one neutral , and a ground. The ground can be #10.

Does it have to be outdoor rated if I run it in a tube?
Yes. No matter how well sealed water collects even if only condensate. Most single conductor wire is dual rated anyway.
 
  #6  
Old 05-07-12, 08:16 AM
Member
Thread Starter
Join Date: May 2012
Location: usa
Posts: 8
So I will need to buy a 6/3 wire outdoor rated wire. Then I need to buy a 10/1 for the ground? Is THHN wire good to use, or Romex? If I am buying that expensive outdoor wire, can I just get direct burrial and skip the tube all together? I am not sure on the type to buy. Why do I need two hots when I am only running a 120 line? Elictricly stupid here
 
  #7  
Old 05-07-12, 10:28 AM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,372
The very first thing you need to buy is the book Wiring Simplified and read it cover to cover. The questions you are asking are elementary and tell me that you do not possess the knowledge to do this job safely. Educate yourself FIRST and then you can do the work.
 
  #8  
Old 05-07-12, 11:18 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,671
Why do I need two hots when I am only running a 120 line?
A subpanel is normally 120/240v not 120 volts. To handle the loads you anticipate a 120v panel would need even more amps then you plan and larger wire. With two hots the 120v loads are split between each hot and the neutral only carries the difference between the hots.

Is THHN wire good to use, or Romex?
No, both are indoor wire only. Either THWN in conduit or UF-b direct burial would be the suitable equivalent for outdoor use however given the distance and load aluminum mobile home (URD) direct burial cable may be a cheaper choice.

To add your idea of stopping a 100 feet from the building and running individual cables is non code compliant because you can only run one power source to a detached structure except in special circumstances which don't apply here. Therefore you are looking at about 300ft and at least #2 aluminum assuming an actual load of no more then 40 amps.

I want to put sub panel as close as possible to the camp using the larger wire. Isnt there less voltage drop using the larger wire than using a smaller wire.
Yes.
I could run multiple lines out of main box using 10/3 but the voltage drop at 300 feet is a lot (i think you only get about 90) I want to have as much voltage and amps as possible at 300 feet from main box.
 

Last edited by ray2047; 05-07-12 at 11:39 AM.
  #9  
Old 05-10-12, 06:28 AM
Member
Thread Starter
Join Date: May 2012
Location: usa
Posts: 8
I am pretty sure what i am doing now... I am going to have a friend who is a retired electician hook up the sub panel, but i have to buy the wire and run it. He is going to do the sub panel itself sometime when he gets back in town. My question is ... i am running #6 wire, do i want 6/3 or 6/2 wire? I have no need for 240 volts ever. Is there a need for 6/3? Can i run two circuits off of one hot and another two circuits off of the other hot and share the neutral and ground? I am no electrian by any means, until my expert comes back i need help on what to buy.
 
  #10  
Old 05-10-12, 07:42 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,671
Is there a need for 6/3?
Yes . If you are installing a subpanel you need four wires,hot, hot, neutral, ground.

Can i run two circuits off of one hot and another two circuits off of the other hot and share the neutral and ground?
One circuit off of each but the maximum breaker size for a general purpose 120v circuit is 20 amps so you would use 12-3. No subpanel would be used. A 120 volt subpanel can be used in special cases but this is not one of them.

but i have to buy the wire and run it.
Wire or cable? Don't confuse the two. If you use "wires" you will need conduit. If you use cable you will not need conduit.

As Furd said:
The very first thing you need to buy is the book Wiring Simplified and read it cover to cover.
Note: If your electrician friend has been out of the business for a while he may not be aware four wires and a separate ground and neutral are required for all subpanels.
 
  #11  
Old 05-10-12, 07:53 AM
Member
Thread Starter
Join Date: May 2012
Location: usa
Posts: 8
I am going to get that book and read it... all of this is very interesting to me... he receently retired so he should be aware of everything... i just have to buy and run the wire and he is going to connect the sub panel at both ends and connect the 4other circuits i want leading out of sub panel... i am running 6/3 wire with ground that is copper and direct burrial UF.. and for the other 4 circuits i am going to run 10_3 i am going to put 50 amp breakers on each end of run... the wire is going to be in a conduit the entire run... see any issues with this?
 
  #12  
Old 05-10-12, 08:18 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,671
i am running 6/3 wire with ground that is copper and direct burrial UF
This is where confusion and miscommunication set in. That is NOT wire. It is cable.

and for the other 4 circuits i am going to run 10_3 i am going to put 50 amp breakers on each end of run....
Why? You only use breakers on the end it is fed from. On the other end you need only a disconnect. To where? You can only run one power source to a detached structure. 30a is maximum breaker size for #10.

the wire is going to be in a conduit the entire run
Wire or cable? Best practice is not to use cable in conduit except for short sections to protect it such as where it enters the ground and leaves the ground.
 
  #13  
Old 05-10-12, 11:23 AM
Member
Thread Starter
Join Date: May 2012
Location: usa
Posts: 8
Ok, I don't know if I am expressing what i want to do with the sub panel. I want to run the 6/3 cable (direct burrial UF, copper) into sub panel with a 50 amp breaker/disconnect on both ends. Inside the sub panel I want to run 4 circuits rated at 20 amps each off of the 50 amp breaker. The max load I am looking at is around 40 amps. Each one of the 4 circuits is going to be 10/2 wire (10/2 because I already have the wire, I know i could use thinner wire). . My electrian friend is out of country on vacation, and I have to get this wire run between the two panels so he can hook it up when he gets back. I am just doing the grunt work, he is going to do the connecting of the wires and running the different circuits. What is your suggestions on how to run a 300 foot run from main pain and have 4 ciruits at the end without the signifcant volt/amp drop?

I just got back from the bookstore, I bought that book and going to read it ASAP hopefully it will shed some "light" on this subject that I apparently know nothing about!!!
 
  #14  
Old 05-10-12, 12:34 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,671
with a 50 amp breaker/disconnect on both ends
You only need the 50a breaker at the main panel. If for instance you use a 100 amp main breaker panel as a subpanel, a common practice, you would not change out the main breaker that comes with the panel because it only serves as a disconnect. If you used a main lug panel and kept the number of branch circuit breakers to six or less the feeder would be connected directly to the subpanel lugs with no breaker.

Best choice price wise would be at least #4 quadplex, direct burial aluminum mobile home cable (URD).
 
  #15  
Old 05-10-12, 01:42 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,372
If you used a main lug panel and kept the number of branch circuit breakers to six or less the feeder would be connected directly to the subpanel lugs with no breaker.
Not quite. IF the subpanel is in the same building as the service panel then no disconnect is necessary. IF the subpanel is NOT in the same building as the service panel then a disconnect (or main breaker) IS required. Since in this case both the service and sub panels are outside (as I understand) then the sub DOES require a disconnect or main breaker.

Also, it is not the number of circuits installed, but the maximum number of circuits that MAY BE installed that triggers the "six throw" rule. Example, if you use an 8/16 panel but only install four circuit breakers you STILL need a disconnect or main breaker if the panel is not in the same building as the service panel.
 
  #16  
Old 05-10-12, 04:58 PM
Member
Thread Starter
Join Date: May 2012
Location: usa
Posts: 8
Thanks everyone for your help on all this... i am gonna get this project started soon, i will look at the #4 wire that you suggested... i just wanna have more power to run my stuff at camp, i have 2 parallel running 10/2 lines now its not enough at the length (300ft). One last question how deep do you have burry the wire?

So to sum this up.. put a 50 amp break on the main panel.. then run the wire (either 6/3 or the #4wire wire you suggested) the 300 feet burried to the depth you tell me from above. Install the sub panel with at least a 50 amp breaker (as disconnect to kill box when i am not there). Then place 4 -20 amp breakers on with 10_2 wire attached (using 10-2 wire because i already have it) the four circuits will not add up to a load of no more than 40 amps. The end of the line will be a receptacle GFI 20 a because this is all outside. I will have the receptacles in the outdoor boxes. See any problems here? Any suggestions?
 
  #17  
Old 05-10-12, 07:23 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,989
Depth for direct burial wire (urd) or cable (UF) is 24"

Breaker in main panel is a MAX of 50 amps, not "at least".
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'