Need help with UF cable

Reply

  #1  
Old 07-30-11, 10:15 PM
Member
Thread Starter
Join Date: Jul 2011
Location: United States
Posts: 4
Need help with UF cable

I want to wire my garden shed for glass blowing. I figure I'll need two seperate 20 amp circuits as my kiln will take up 15amps; my other appliances will consist of about 500w of lighting, a window air conditioning unit, a small space heater, and possibly some oxygen concentrating machines. I am fairly new to wiring, but I have done some research and think I will be able to do it all myself. I have chosen to use UF cable because the shed is about 50 yards away from my house and my local regulations do not allow me to go above ground/hang the wire.

I'm asking for any help and/or tips before I jump into this. I'll be updating this thread with progress as I move along.

Here is a list of the appliances I hope to run:

Glass Kiln:15 amp/120v
Lights:Approximately 500w worth
Window A/C Unit:Approx 5 amps/120v
Attic Fan: Unknown wattage, about 1500cfm/120v

I will be running tanked oxygen for the time being, until I upgrade to concentrater machines. So I won't be needing the extra amperage for them right away, but may have to add another circuit for them down the road.

I plan on having two outlets for the circuit that is not on the kiln, and one outlet for the one that is. For the non-kiln circuit, I also want to have a lightswitch that controls the entire circuit; fan, lights, AC, outlets.

If I'm missing anything or have left an important detail out, please let me know. Thanks.
 
Sponsored Links
  #2  
Old 07-31-11, 12:51 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,659
You can only run one circuit to a building not attached to your house. Anymore would not be code compliant.

You are going to need to install a subpanel in the shed. For now I would a 30a subpanel will probably be enough but use minimum of 1" conduit with individual THWN wires. That way you can later upgrade to a 40 or even 60 amp feed to the subpanel in the shed.

The subpanel in the shed should be at least a 100 amp to give room for several beakers. Initially you would use four #10 THWN wires fed by a 30 amp breaker in your main panel. That is just the basics. There are more details to doing it correctly but I will leave that till you post back.
 
  #3  
Old 07-31-11, 06:25 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
Ray, to take into consideration future upgrades, would installing #6 wires (although overkill for now) be advisable. That way increasing the amperage to the building wouldn't require running new cable. Just a thought.
 
  #4  
Old 07-31-11, 06:30 AM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,213
I believe one 20 amp multi-wire branch circuit would be code compliant, but I wouldn't put in a marginally acceptable circuit now if it had to be replaced later, especially using UF cable that is labor intensive to replace. I like Ray's idea of a subpanel and using conduit. In my opinion, you need more than 2 circuits anyway regardless of the minimal loads you think you have now.
 
  #5  
Old 07-31-11, 07:36 AM
Forum Topic Moderator
Join Date: Sep 2005
Location: USA
Posts: 4,059
Just to throw one more opinion in the ring...

A multi-wire branch circuit (12/3 UF connected to a double-pole 20A breaker and split into two 20A 120v circuits at the shed) would satisfy your current needs.

That said, if it were me, I'd run 1" or 1.25" PVC conduit to the shed and pull four 12ga THWN wires through it (hot/hot/neutral/ground). A few years down the road, if you want to upgrade to a 30A or 60A subpanel, you can just by pulling new wires and no digging!

I'd also drop in the same trench a 3/4" or 1" PVC conduit for future telephone/network/intercom/whatever low voltage needs. Now would also be a good time to add a 1" black plastic water pipe if you want water out there too. (but that may be a bit too much pre-planning)
 
  #6  
Old 07-31-11, 09:07 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,659
The OP hasn't said if the current kiln is 120v or 240v. Without knowing that it would IMO be premature to advise a MWBC even on the short term.

Ray, to take into consideration future upgrades, would installing #6 wires (although overkill for now) be advisable.
Not a pro but IMO yes if he can afford the slight difference in cost.

Alienscience, is the Kiln 120v or 240v?
 
  #7  
Old 07-31-11, 09:29 AM
Justin Smith's Avatar
Member
Join Date: Dec 2010
Location: Cressona, Pa, USA
Posts: 2,546
The OP hasn't said if the current kiln is 120v or 240v. Without knowing that it would IMO be premature to advise a MWBC even on the short term.
Glass Kiln:15 amp/120v
Alienscience, is the Kiln 120v or 240v?
He answered these in his first post.
 
  #8  
Old 07-31-11, 10:01 AM
Luana's Avatar
Member
Join Date: Oct 2008
Location: United States
Posts: 143
Conduit with a 100 or 125 ampere panel makes the most sense. Siemens has an 8 space / 16 circuit 125 ampere panel for less than $30 at one of the big box stores.

I would NOT run anything less than #8 conductors and #6 would be better. No sense in running smaller wires that will need to be replaced in the near future.
 
  #9  
Old 07-31-11, 10:05 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,659
Originally Posted by Justin Smith View Post
He answered these in his first post.
OOps, thanks for the correction.
 
  #10  
Old 07-31-11, 10:17 AM
Justin Smith's Avatar
Member
Join Date: Dec 2010
Location: Cressona, Pa, USA
Posts: 2,546
Square D also makes a 6 space 12 circut for under [email protected] big box orange.
 
  #11  
Old 07-31-11, 10:37 PM
Member
Thread Starter
Join Date: Jul 2011
Location: United States
Posts: 4
Thanks everyone for the help. I can tell this is going to take a lot of planning and work.

For the subpanel, is it as simple as wiring a circuit to my 'main' panel in my house? Would I need to use a special breaker with high amperage or voltage?

From what I can gather as of right now, I need to wire a 'sub-panel' to my shed that will run approximately 30 amps of electricity through it. I will also have to use some type of conduit between my house and shed.

What all will I need for this?

A subpanel (what kind)
Breakers (amperage, #)
What is THWN wire (another underground medium)
Type of conduit

If I could get a list of everything I need to buy, I'm sure I could use it work out how to do it.

Thanks for everyone's help so far.

PS. Thanks for the heads up on the # of circuit code.
 
  #12  
Old 07-31-11, 11:21 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,374
Your first step is to purchase the book Wiring Simplified. It is available in the electrical aisle (but generally NOT where the other books are located) at the mega mart homecenter. You might also want to check out some DIY type electrical books from your local library. These books will have answers to most of your questions and also to the questions you don't yet know to ask.

Yes, it IS a fairly simple job but with many details. You would normally use PVC electrical conduit and have it buried 24 inches deep from the surface to the top of the conduit. Where it comes out of the ground it needs to be protected from physical damage. You cannot have more than a total of 360 degrees of bends in the conduit without having a "pull point".

The 30 amperes at the sub-panel is a bare minimum. It is best to be oversize on the sub-panel and as already mentioned 100 or 125 ampere panels are available at minimal cost. The circuit breaker in the house (service) panel must be compatible with the panel, usually made by the same manufacturer as the panel. The amperage size depends upon the size of the conductors between the service panel and the sub-panel. Type THWN is an insulation type on individual conductors that is suitable for underground conduit systems, usually dual rated as THHN/THWN. You will need four lengths in total, one white, one green (or bare) and two of any color other than white or green.

Please, get the book first and read it well BEFORE buying any other supplies. It isn't rocket science but you DO need to follow the codes. Most areas will require that you get a permit from the "Authority Having Jurisdiction (AHJ), generally the building department at your local city hall or county offices before commencing work.
 
  #13  
Old 08-01-11, 09:02 AM
Justin Smith's Avatar
Member
Join Date: Dec 2010
Location: Cressona, Pa, USA
Posts: 2,546
Your subpanel also cannot have more than 6 disconnects(breakers) before it needs a main breaker.
 
  #14  
Old 08-01-11, 09:15 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,659
If he buys a low cost main panel to use as a sub as suggested they usually come with a main breaker installed.
 
  #15  
Old 08-02-11, 01:32 AM
Member
Thread Starter
Join Date: Jul 2011
Location: United States
Posts: 4
Looks like I'll be hiring an electrician. Any idea on how much it will cost me? The shed is farily old, and I don't plan on working out of it for more than a year, but if I cut out the AC unit and down on the lighting, I should be able to keep it under 30 amps correct?

Does the length from the 'service' panel require the sub panel? Or is it the amperage? I have a feeling it's going to cost a lot more to have a sub panel wired than it would to just have a 30 amp circuit run to it.

Normally I would take something like this up by myself, but I'm busy learning glass and don't have the time or energy to study wiring. Thanks for the help everyone.
 
  #16  
Old 08-02-11, 08:50 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,295
Originally Posted by alienscience View Post
but if I cut out the AC unit and down on the lighting, I should be able to keep it under 30 amps correct?
You could get by with a 20A multiwire circuit wired with 12-3/g UF-B cable. It is not expandable for future growth, but it would meet your current needs.

Or is it the amperage?
It is the amperage (wattage actually). The maximum you can deliver with a single circuit (20A MWBC) is 4800W peak / 3800W continuous. I think if you add up your proposed devices you will find that the 20A MWBC option is maxed out. Any additional loads you want to add will require a subpanel.
 
  #17  
Old 08-02-11, 11:03 AM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,374
...don't have the time or energy to study wiring.
Then definitely hire a QUALIFIED electrician. Electricity is an equal opportunity killer.
 
  #18  
Old 08-02-11, 06:47 PM
Justin Smith's Avatar
Member
Join Date: Dec 2010
Location: Cressona, Pa, USA
Posts: 2,546
Then definitely hire a QUALIFIED electrician.
Make sure he is liscenced. Don't hire a handyman or General contractor. A majority (but not all) of these don't know what they're required to be doing. You want a liscenced electrician. VA has liscences.
 
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
'