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oxford
12-05-2012, 06:38 PM
I have a couple questions for the electricians on here. I am running power out to my garage from the house. The total wire length will be around 150 feet. I recently got a real good deal on some copper 4 gauge THWN. What is the maximum size breaker I can run it from off of the house panel? I could not find a temperature rating on the insulation of the wire. This will be standard 220v single phase.

Also, around 90' will be in conduit from the garage to the house under ground. Once I get into the house does THWN still need to be in conduit or can it be run like romex? It is running through an un-finished basement to get to the panel. Thanks.

Fasttrack
12-05-2012, 06:46 PM
I have a couple questions for the electricians on here. I am running power out to my garage from the house. The total wire length will be around 150 feet. I recently got a real good deal on some copper 4 gauge THWN. What is the maximum size breaker I can run it from off of the house panel? I could not find a temperature rating on the insulation of the wire. This will be standard 220v single phase.

Also, around 90' will be in conduit from the garage to the house under ground. Once I get into the house does THWN still need to be in conduit or can it be run like romex? It is running through an un-finished basement to get to the panel. Thanks.

I'm no electrician, but I did recently read through the NEC as I was working on my house. The THWN needs to be in conduit; Romex and other non-metallic sheathed cables are permitted by the NEC because the sheathing acts like a conduit to protect the insulation on the individual conductors.

In order to be compliant with the NEC, you should size your breaker according the following ampacities of the conductor:

Insulation temperature 60 degrees C: 70 amps
Insulation temperature 75 degrees C: 85 amps
Insulation temperature 90 degrees C: 95 amps

When sizing conduit, you also have to be sure to follow NEC guidelines. I can't remember now the details, but they give you a formula to calculate the size of the conduit needed based on the number of conductors and the percentage of cross-sectional area filled.

Read this ... think it has everything you need to know...
http://www.fs.fed.us/database/acad/elec/greenbook/3_basicdesigns.pdf

lakeside53
12-05-2012, 08:53 PM
Unless everything end-to-end is 90C, you need to default to the lower temperature spec. THWN is 75C, but your domestic panel and breakers may be 60C. Look at the labels inside the source and destination panel. Also, there should be a spec number on the wire that can be referenced.

Is the 150 feet one way or loop distance? Althought it's not an absolute under the code (but may be in your local jurisdiction), the recommendation is to keep the overall voltage drop less than 3% on branch circuits, and 5% overall.

Yes, you must protect THWN in L&L conduit and boxes. You are going to need to extend neutral if you want to derive 120v circuits, and install a ground rod at the garage sub-panel (do not extend ground to the garage). If your sub-panel is not acessible and near a door you local codes may require an external full building disconnect switch.

Dr Stan
12-05-2012, 09:15 PM
here's a site I've found helpful http://www.make-my-own-house.com/diagram-electrical-wiring.html

J Tiers
12-05-2012, 11:51 PM
Expanding on what Lakeside wrote......

The terminals on the ends need to be rated for the wire temp, if you use the wire to full temp rating. Usually the temp rating is marked on the breakers.

You can use higher temp wire, just not to full temp unless the terminals are equally rated. The exception is if you run through a hot area between cooler areas, like up through an attic and down to the living space again. Then you derate the wire for the higher temp for that part of the run, but since it is rated higher to begin with, the derating does not force you to use larger wire. And the wire is still OK at the lower temp for the terminations.

Mr Fixit
12-06-2012, 12:43 AM
Oxford,
Hope you are in the states, your name implies different? :rolleyes:
The NEC (National Electrical Code) is a minimum guidline that most counties,cities towns and others require you to follow. Now to your questions.
The above answers are correct you do need to use the 60* rating which does have the wire rated at 70amps, so a 70 amp breaker at the house is what you want, it is to protect the wires to the shop. About the wire in the house yes it will need to be in a raceway and PVC is not allowed inside as it puts off toxic gases when heated or burned. EMT or even rigid galvinized conduit will work. You can pull a ground in with the conductors in PVC pipe underground and I highly recommend it (this is called an equipment grounging conductor, green or bare) to the shop, But YOU MUST Keep the ground bar and neutral connections seperate. Yes most jurisdictions require a seperate ground rod for an unattached building on the same service. A#6 solid from it to the ground bar is what you will need for that part of the install.
You will want to include a neutral (white wire) so that you can have 120v circuits even though you will use 220v for most equipment and welders.

I am repeating things already said but it does help to get as much information as possible when taking on a job like this.

Best of luck and feel free to ask more when you get going. :D

Mr fixit for the family
Chris

lakeside53
12-06-2012, 01:09 AM
Yes OXFORD, please fill in your profile location! If not, none of the above may be correct!

You local jurisdiction may allow the use of PVC conduit (there is also HDPE, subject to separate rules under Article 353) inside residential single family home, but you need to check with your AHJ - it often depends on whether you are three stories or less. With any conduit runs, pay attention to pull points with no more than 270 degrees of bends between them. And... no mixing plumbing connections with electrical, even if they fit!

oxford
12-06-2012, 12:52 PM
Thanks, yes I am in the states. I am pulling a neutral, I have enough wire to pull 3 #4 and have to pick up something for a ground wire. What is considered a pull point? I currently have 6 90 degree bends to get from the house panel to the garage panel. The first 2 will be LB fittings to get from the subpanel to the outside, I then have 1 90 elbow to get heading towards the house. Once inside the house, I could use whatever.

So at 60 degrees, 150' wire length, I am ok with a 70amp breaker at the house panel?

ogre
12-06-2012, 01:22 PM
Not sure if this applies but i upgraded my home to 200amp service and it required 2 grounding rods to be installed in the ground no closer than 4 feet i believe. Some new code at the time i blieve.

Paul Alciatore
12-06-2012, 02:01 PM
I have done these things and even with all the lube in the world, there is no way you are going to be able to pull that mass of wire through 6 90 degree bends. For long runs, even one 90 can be problematic. Six 90s is twice the recommended 270 degrees and even 270 degrees can be difficult. You are going to need at least one pull box somewhere along this route and personally, I would use two. I would try to plan a straight run from house to garage with only two 90s to transition from horizontal to vertical. A weather proof, outside box at each end of this run would make pulling much easier and each of these boxes can also function as one of your 90s. Then one or two 90s from these pull boxes to the house and garage panels and you are done. Make these boxes large enough to allow pulling both ways from them and you will not need to splice the wires in them. I would think 12" x 12" or even larger.

Oh, and wherever you can, DO use the large radius or "sweeping" 90s. They also make pulling a lot easier. A lot.



Thanks, yes I am in the states. I am pulling a neutral, I have enough wire to pull 3 #4 and have to pick up something for a ground wire. What is considered a pull point? I currently have 6 90 degree bends to get from the house panel to the garage panel. The first 2 will be LB fittings to get from the subpanel to the outside, I then have 1 90 elbow to get heading towards the house. Once inside the house, I could use whatever.

So at 60 degrees, 150' wire length, I am ok with a 70amp breaker at the house panel?

dave5605
12-06-2012, 02:17 PM
You don't have to count the 'LB's as bends because you open them up to pull the wire to/from them and they become the equivalent of the 'pullbox'. Be sure to use more than enough wire pull lubricant on the wires when you pull them. Lather them up real good as they enter the conduit and keep lathering them up. One person pull and one person lather. Pull all the wires at the same time as one bundle.

Pretty sure (haven't kept up with the last few code revisions though) you have to run the ground wire between the two panels too even though you have ground rods at the sub panel.

Ron of Va
12-06-2012, 03:59 PM
I upgraded my electrical service about two years ago. I had 125 foot run. Not much wire pulling involved. Three strands of 2/0 copper. Two hots and a neutral, with a grounding rod at the garage.

They (electricians’) dug a trench. Laid conduit and wire along the trench, then they started at the garage and fed the conduit over the wire one length at a time to the house, laying the conduit in the trench as they went. Then they glued it up.

At the garage they installed a junction box on the outside wall where they terminated the THWN wire. There they connected 2/0 Romex and ran it from the junction box, through the wall and up to the panel. They did a similar thing at the house, went through the outside wall underground with the conduit/THWN, then ran it in the crawl space to a junction box, then to the panel with 2/0 Romex.

oxford
12-06-2012, 05:59 PM
Out of curiosity, what makes romex able to be left in the open but thwn needs to be in conduit. Isn't romex just 2/3 pieces of thhn and a bare wire with the jacket around it. Honestly the jacket isn't much of "protection".

Ron of Va
12-06-2012, 07:14 PM
Out of curiosity, what makes romex able to be left in the open but thwn needs to be in conduit. Isn't romex just 2/3 pieces of thhn and a bare wire with the jacket around it. Honestly the jacket isn't much of "protection".
I don’t know if it was “Romex” exactly, but it looked like it to my untrained eye. They used it because it was more flexible to get into the box. Here it is hanging out of the junction box. They already ran it to the electrical panel. It was never run in the open.
http://www.hunt101.com/data/500/medium/GarageConnection.jpg

Ron of Va
12-06-2012, 07:31 PM
Oxford.
I told the contractor that I would fill in the hole. He loved that, 98ļ in June.

I covered the electrical conduit with about 10 inches of dirt, then ran about a half a dozen Cat 5 cables, a couple of telephone lines, 4-5 coaxial cables in another piece of electrical conduit right on top and covered it all up. I am thinking about putting in a security system. I didnít know what I would need, so I though I would cover the bases. I already had most of the cables on hand.

Something to think about.

lakeside53
12-06-2012, 07:54 PM
Out of curiosity, what makes romex able to be left in the open but thwn needs to be in conduit. Isn't romex just 2/3 pieces of thhn and a bare wire with the jacket around it. Honestly the jacket isn't much of "protection".

Because it has that outer jacket... effectively a conduit. Right or wrong, it is the code :)

oxford
12-06-2012, 08:13 PM
And that code makes as much sense as John Bobbit wearing a condom for protection when he got his wiener cut off with a knife.

darryl
12-06-2012, 08:14 PM
No comment on the wire size, ampacity, etc- but it seems to me you have a 'kit' there- wires, tubing, els, etc. I'd be pulling the wire into the straight sections, then feeding the els over the wire and gluing them up, etc. I have some experience feeding bundles of wire into conduits to be buried, and it can sure bind up in a hurry. I used to use talc (baby powder) and vacuum it into the conduit, then also run the bundle through a cloth saturated with powder as it's being inserted.

Before this, I would take a cloth and tie string to it, then vacuum that through the conduit. Takes about 3 seconds to go 50 or 100 ft- then I'd use the string to pull some rope through, then use the rope to pull the wire through.

I think you'd want to build as much of this as possible before having to feed the ends into the buildings- just so it's actually possible.

lakeside53
12-06-2012, 08:22 PM
Guys, it's only 4awg... slap in 1 inch conduit as one glued piece (even 3/4 is fine....) dump in lube if you need and pull it though! Try 500 and 750mcm copper if you want a real stuggle even with a tug! if the wires isn't on reels, lay it out nice and straight and have one guy feed it in while the other pulls.


Buy your conduit in 20 ft sticks - and the type has the female end belled into the conduit.

lakeside53
12-06-2012, 08:25 PM
I don’t know if it was “Romex” exactly, but it looked like it to my untrained eye. They used it because it was more flexible to get into the box. Here it is hanging out of the junction box. They already ran it to the electrical panel. It was never run in the open.
http://www.hunt101.com/data/500/medium/GarageConnection.jpg

Hmmm... what bury depth did you use? maybe it's the photo, but that doesn't look like 18 (general depth) or 24 (if in street) inches to me.

oxford
12-06-2012, 08:27 PM
I was not really worried about pulling the wires. I plan on running 2" conduit so it will be easier to pull and so in the future if I decide that more power is needed it will be easier to pull them through. It is only a 75' straight section under ground to 1 elbow then to the LB's. So back to the original question, what is the biggest breaker I can run at the house?

lakeside53
12-06-2012, 08:29 PM
Based on what we know from you, 70 amps.

Ron of Va
12-06-2012, 08:38 PM
Hmmm... what bury depth did you use? maybe it's the photo, but that doesn't look like 18 (general depth) or 24 (if in street) inches to me.
It is 24", it's the photo.

oxford
12-06-2012, 08:44 PM
Based on what we know from you, 70 amps.

Thanks.

lakeside53
12-06-2012, 08:49 PM
I was not really worried about pulling the wires. I plan on running 2" conduit so it will be easier to pull and so in the future if I decide that more power is needed it will be easier to pull them through. It is only a 75' straight section under ground to 1 elbow then to the LB's. So back to the original question, what is the biggest breaker I can run at the house?



So.. what size conduit will you run inside;l surely not 2 inch?