New member working on electrical work

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  #1  
Old 12-04-06, 05:04 AM
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New member working on electrical work

Hi everyone,

I just found this forum and wanted to say that it's great. I've already picked up on some helpful hints...and am looking to see if I can get some assistance with a future project.

I'm also going to apologize in advance if my question has been already asked.

I'm a pretty handy DIY-er. I watched my father for 20 years (he was a general contractor), so I'm pretty handy.

I've already run lines into the electrical panel and different things like that....

so my question is the following.

I'm thinking about running a new 20 amp line from my house to my garage. The garage is about 15-20 from a rear corner of my house.. and running any counduit would not be overly difficult because I wouldn't need to go under any concrete or other obstructions...

I've taken a look at some DIY electrical publications and think I have the overall idea on how best to do this, but I wanted to double check with some people that have a better understanding on the how to do this the correct way.

First, I understand that I will need an LB fitting on both the side of the house and garage. In my town, the code was recently changed to allow either Metal or PVC (gray plastic) - not sure if it actually is PVC.

From the LB fitting I would run conduit down into the my ditch and then put a 90 degree turn...

So, my question is the following...

What is the best type of cable to run... in some books I have seen show no additional conduit after the 90 degree turn.. it just has the grey/ underground cable exposed. Is it better the fill the gap with conduit and then use another type of cable... for instance, if I used grey PVC conduit for the whole thing, could I just use 12 gauge NM or Armor Cable through the PVC. Or is it just better in all to use metal conduit.

also, every PVC LB fitting I have seen does not have anything that anchors them to the house... the problem I have with my house is that I can really secure any PVC nipple (going through a brick wall) with an outlet box from the inside.

So, I would really appreciate it if some experts could give some guidance on this one....

Thanks everyone
 
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  #2  
Old 12-04-06, 05:20 AM
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You must use a cable the is rated for wet. Even with the conduit it is still a wet location. NM cable would not be suitable.
 
  #3  
Old 12-04-06, 05:41 AM
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Can you run the underground wet cable through the conduit?

Or should you end the conduit after it makes the turn in the ditch?
 
  #4  
Old 12-04-06, 05:52 AM
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UF Cable can be run underground without conduit, if it is deep enough. Individual wires of appropriate type (THWN) must be run in conduit.

There are a few more things to be wary of. You are only allowed one circuit top your detached garage. If there already is a circuit to your garage you cannot run a second. Your options, if this is the case, are to replace the circuit with a multi-wire circuit or to upgrade to s sub-panel in the garage.

If you have no circuits in your garage then you need to think about what your needs are at the garage, and plan accordingly. Running conduit might be appropriate, so you can upgrade later. However, if you think later will be next summer then you might want to run the appropriate cables now.
 
  #5  
Old 12-04-06, 06:47 AM
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Well you have several things to consider. If you are going to just have a 120 volt 20 amp or 15 amp circuit to the garage or are you going to have a 240 volt circuit with sub-panel and breakers in the garage.

You cannot use NM cable it is not rated for wet locations. You can use UF-B cable. there are other choices but UF-b is the most common for DIY.

However it is not adviseable to run sheathed cable through conduit except short sections used for physical protection like from the LB to underground. Once underground just lay the cable in the trench exposed and then bury it directly.
As far as the wiring method for the circuit to the garage: If you are using direct burial cable such as uf-b you would use the Lb's and most likely PVC pipe. Your trench needs to be 18" minimum. Use a 90 degree sweep fitting at the bottom of the trench. Then just run the cable in the trench to the garage repeating the same process above ground as at the house. As for securing the LB's you would use clamps on the vertical run of the conduit on the side of the house. You want at least one clamp within 12 inches of the LB. If this is brick then use appropriate anchors to hold the clamps. Seal the hole you make for the nipple going through the brick with duct seal or a high grade silicone caulk.

The other method would be individual wires in a closed conduit run from house to garage. The wires need to be thwn rated for wet location. this wiring is readily available at the box stores and is THHN/THWN rated. Use stranded wire not solid when pulling through conduit. Build the conduit run from house to garage. If it is a long distance then install a pull string as you go to pull the wiring through when you have completed the conduit installation. Remove the back cover of each LB. You can either pull the new wires from LB to LB or panel to panel just depends on the difficulty of the pull and how full the pipe is with wire. Short runs you can use a fish tape. Just be darn careful when using a metal fish tape in the house panel. I prefer nylon fish tapes for this application. Generally I prefer feeding the new wire LB to LB then LB to panel.

Metal conduit is ok but generally gray PVC sch 40 electrical conduit is fine and a better choice for DIY. I dont recommend EMT... if you want to use metal go with RMC (rigid metal conduit). However you need threading tools and reamers to work with it whereas with PVC just glue fittings and PVC saw. RMC only needs 6" of burial vs 18" for pvc.

In many areas codes require sch 80 pvc where your wire/cable needs protection from damage. The NEC requires sch 80 but there is a good chance sch. 40 will be allowed but you need approval to use it. This protection is generally required above ground outside the house on direct burial methods. Conduit from panel to panel of course is a no brainer. Sch 40 pvc when underground is fine everywhere.

If you describe what you want as to power at your detached garage we can be more specific.

EDIT: If you use conduit and individual wires you must have a complete run of conduit panel to panel. You are not allowed to have individual wires not in conduit once you enter the garage or house. Cables like uf-b are fine exposed but they still must follow framing members or bored holes and stay inside the wall cavities.

Roger
 

Last edited by Roger; 12-04-06 at 07:03 AM.
  #6  
Old 12-04-06, 07:19 AM
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Thanks So much everyone..

Roger's last comments were exactly what I was looking for...

My goal is to just run a 20 amp line - I live in a humid area of the North East and my garage is unfinished, so I don't plan on running heavy duty tools out of there (atleast not at this point).

I just want to replace the existing hookup because it looks like they just cemented armor cable through a hole close to the bottom of the garage and through a basement window opening... I don't like the set up because the wiring is old and seems a bit frail.

I realize that it should be OK if I don't touch it, but it just bothers me - plus right now it's only a 15 amp line.. so the 20 would be a slight upgrade.

Thanks again.
 
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Old 12-04-06, 07:42 AM
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if you place a junction box inside each building, you can convert from THWN inside the conduit to NM outside the conduit and inside the structures.
 
  #8  
Old 12-04-06, 07:52 AM
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You need to have a disconnect in your garage. This can be as simple as a wall switch. Locate it shortly after you come into the garage with the circuit.

Put it in a nice 4x4 box then run from that box to your lights and receptacles.

This is a good read for what you want to do.... just copy and paste. Read the first part of the article then scroll down to the pictorial showing your application.

http://www.selfhelpandmore.com/homewiringusa/2002/accessory/detgarage/index.htm

Roger
 
  #9  
Old 12-04-06, 09:30 AM
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Putting in minimum 3/4" PVC Sch 80 is a good idea. That will give you some capacity in case you want to upgrade later to a subpanel, or add a 3-way to turn on yard lights while you're in the house.

Also consider running a larger parallel conduit for low-voltage. I know, I know, with cordless phones what do you need that for? Maybe cable TV or an alarm system ... battery-operated sensors probably won't do well in the cold. Or maybe your garage would be a better place for a satellite TV antenna than your house.

It's cheap and easy when the trench is still open, even if you just stub it up without the fittings to get into the buildings.
 
  #10  
Old 12-04-06, 10:59 AM
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You know that's an interesting point about the low voltage...

But it's a good idea...

But it also makes things more complicated...
If I mistate something, please let me know.. I'm going off of my understanding of everyone's helpful comments.

After previous comments, I was planning to just run the UF cable...
I like the THWN method, but it is also seems to be more difficult.

I need to run about 20 feet of cable from the panel, through an exposed basement ceiling, to where I wanted to cut in through the brock exterior for the LB to go outside. As I understand it, using THWN is more difficult because I would need to run conduit inside the house to protect the non- sheathed wires... so using UF-B solves that dilemma because I can run it from the panel, though the ceiling, out of the LB into the 90 sweeps and then into the ground. It was stated before that sheathed cable should not be used in conduit except for short distances, like from the LB through the sweep and into the dirt.

How do I incorporate running conduit for low voltage using this approach?

Also to confirm, once the live feed comes into the garage, I should put a switch right there...before running it to any outlets or real switches.

My overall goal is to have a couple of outlets (including an outlet for a garage door opener for the future), a switch and light inside and a switch for a light over the garage door for external use... I would really appreciate it if anyone has any further recommendations of what I may want to consider... I really don't envision a need for a separate sub-panel... plus, I feel that's way over my head and I don't really think I need that much power out there. I use my basement as my workshop area....


I really would welcome any suggestions about alternative approaches for low voltage lights... my backyard is somewhat dark and I would like to light up some landscaping in the future...
 
  #11  
Old 12-04-06, 11:02 AM
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Also, what is the correct height for an LB fitting. I live in New York in case that matters....
 
  #12  
Old 12-04-06, 11:10 AM
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You can mix cable and individual wires in conduit without issues. Just install a junction box on each end of the conduit. One will be in the basement, the other will be in the garage. Run THWN between the two junction boxes through the conduit. Use NM-B from the panel to the basement junction box and attach to the THWN. In the garage you can keep the conduit (which may be needed for protection) or transition to NM-B if that will work.

The suggestion for running a second conduit for low voltage wiring is to make it convenient to add these in the future if you need them. Just run a second piece of conduit in the trench, maintaining a separation of at least 12 inched between the two conduits, but leave the ends open in the garage and basement (put a cap on them to keep air water and dust out/in, but leave enough excess pipe so the cap can be removed.

With the conduit in place, you can add, at a later date, a telephone line, for example.
 
  #13  
Old 12-04-06, 11:18 AM
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Racraft, it is OK if the TWHN wire goes say 2 feet before hitting the junction box. I'm going to have to let it hand from the LB until I can reach a junction box.


Does the code allow for that? - I would be hesitant without confirmation.
 
  #14  
Old 12-04-06, 11:21 AM
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Speaking of the conduit and junction boxes... let me get this straight...

I have the PVC LB outside on the garage wall, with a PVC nipple running through the hole, and then the best is to attach is right to a junction box.... the box would be metal, right? Do I just find/make a PVC nipple with a threaded end - and use a PVC "bolt" on the metal junction box to hold it together?
 
  #15  
Old 12-04-06, 11:24 AM
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THWN wires must always be inside a raceway or junction box. The PVC conduit is a raceway. Go from PVC to a junction box (metal or plastic) in the manner you have indicated.
 
  #16  
Old 12-04-06, 12:31 PM
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Mark.... here is a link to carlon pvc fittings which is usually what most of the big box stores carry on hand.

http://www.carlon.com/scripts/emAlbum.cgi?cmd=show_thumbs&path=Rigid_Conduit_Fittings_Accessories&tn=1

There are a couple ways to connect to jb's.... use a threaded box connector fitting that glues to the pvc then install the box and secure with a lock nut that threads onto the box connector from inside the jb.

Or you can use a glue on connector that intalls through the knockout hole of the metal box then onto the pvc. These are permanent and requires cutting the pvc if you need to make a correction.

There are fittings for about every situation you will face.

As for the LB height you put it where it needs to go there is no set location. As for the junction boxes you can put them anywhere you want. Generally if you install them to the nipple coming thru the wall you will want to use an entry from the back of the jb so get one that has rear knockouts. I wouldn't do this if I have to anchor it to brick. I would come on inside till I got to a wooden framing member then put in the jb.

Roger
 
  #17  
Old 12-05-06, 01:38 PM
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Another option is to run NM to a JB on the exterior side. You can put a weatherproof GFCI receptacle here and start with the conduit. You get the benefit of an extra outlet and not having to go as deep with your conduit or UF since it is gfci protected. If you trip the GFCI you dont have to go all the way back in the house to reset it.

Good luck.
 
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