Detached garage feed

[Hondaracer2oo4]

I am building a 28x40 garage this spring. The garage is detached from house. It will be about 55 feet from the house. I am going to run a sub panel in the garage tapped off my panel in the house. The run from the panel in the house to the sub in the garage will be in the neighborhood of 110-120 feet when you account for turns in the wire Etc. My thought was to run a 60 amp breaker off the main panel and use a main lug panel in the garage. First my plans are to run a 180 mig welder once in a while and a Lincoln tombstone welder once in a while. Those would be the two highest consuming power items. Other than that I will put a two post lift in at some point which will be 220. Anyone think that 60 amps isn't enough? So my real question comes down to someone that is knowledgable about carrying capacity of wire. Is 6/3 with a ground wire going to be sufficient or not over that run? I think I am pushing it with 60 amps at that length with 6/3. Could I run 4/3 in the basement which is about 45 feet into a junction box and then step down to 6/3 for the underground conduit to go out to the garage which will be about 65 feet if the 110-120 feet is to much?

 

[pattenp]

Use a main breaker panel, not main lug. Also consider 2-2-2-4 MHF for the feeder.

 

[Hondaracer2oo4]

Would you mind explaining? Thanks.

 

[Hondaracer2oo4]

Like this? http://www.homedepot.com/p/Southwir...ded-Al-Quad-****-URD-Cable-55417399/205001803

 

[Alchymist]

What pattenp said ^^^.

2-2-2-4 is aluminum mobile home feeder. Put a 90 amp breaker in your main panel. A 100 amp panel in the garage with a main breaker - 20 position panel would be good. Match your garage panel with your house panel so they use the same breakers. Ufer ground in garage. Check with you local electrical inspector for any considerations above and beyond NEC , permits required, etc.

 

[Alchymist]

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheetOEM47

 

[Hondaracer2oo4]

http://www.homedepot.com/p/Southwir...Gray-Stranded-Al-MHF-Cable-30163099/205001794

So this would be what I am looking for? I will run this in a conduit underground to keep from getting any issues in the future, I assume I need to run it in conduit inside the home as well? Some of the MHF wires say that they can no be used INSIDE a structure, what tells me that it can be used inside?

 

[CNGsaves]

^ ^ ^ The MHF Al 2-2-2-4 that PattenP recommended is "standard GJ solution" because it's low cost (like $1.50/ft) and works great to give you 90A if garage is not too far from house. He's electrician so good advice.

Run in conduit the whole way end-to-end. That is requirement with MHF that it MUST be in conduit when inside building. It can be direct bury outside, but still recommend 2" conduit so your wire feed will be protected the entire run.

Dig trench plenty deep so the 2" conduit for MHF can be at bottom in some sand, then backfill 12" and put in another conduit for low voltage wiring like CATV (RG6) and internet/phone/security (CAT5e).

 

[Hondaracer2oo4]

http://www.homedepot.com/p/Southwir...Gray-Stranded-Al-MHF-Cable-30163099/205001794

Ok so it looks like this is the winner. So 2 inch pvc conduit I assume, any reason to go so big on the conduit?

 

[zendriver]

What pattenp said ^^^.

Put a 90 amp breaker in your main panel.

Why a 90? just curious, since i'm planning a similar project and have about 70' to run.

 

[pattenp]

Would you mind explaining? Thanks.

The Mobile Home Feeder (MHF) is a good cheap solution to give you some overhead for power capacity. You can put it on a feeding breaker up to 90A. The MHF can be direct buried but does need to be in conduit where above ground and inside the structure. But it's best to use conduit for the whole run, panel to panel. If you consider URD cable it has to be terminated outside the structure and will require transitioning to SER for the run inside which would not require conduit inside. Some places may try to sell you URD, so be mindful that MHF and URD are different and that URD has to stay on the outside of the building.

Wire and Cable to Go sells the MHF if you can't find it locally. Their prices are good even with shipping. http://www.wireandcabletogo.com/Mobile-Home-Feeder/


If you end up with more than 6 breakers in your sub-panel NEC requires there be a main disconnect. So it's best to just use a main breaker panel for the sub-panel. I suggest at least a 100A main breaker panel with no less than 20 spaces.

 

[pattenp]

Why a 90? just curious, since i'm planning a similar project and have about 70' to run.

90A is the max for #2 aluminum as a branch feeder. You can use as low as a 50A breaker as it becomes an issue of the wire not fitting into the breaker lugs.

 

[Hondaracer2oo4]

Thanks for the great advice. Any reason that it has to be in such a big conduit, 2 inches?

 

[pattenp]

Thanks for the great advice. Any reason that it has to be in such a big conduit, 2 inches?

The 2" is a readily available size and makes it really easy to pull the #2-2-2-4 MHF. You should use no smaller than 1.5". I believe by NEC you can actually get by with 1.25" but I imagine it would be tough to pull even with using a ton of wire lube. You could use the #2-2-4-6 MHF and maybe get by with the 1.25" if you have a need to use smaller conduit.

 

[rvieceli]

The bigger conduit makes for an easier pull.

the price difference even at Home Depot is only slightly more than $1 per 10 foot stick for the bigger conduit. So in your 120 foot run would probably only cost you about 20-30 more even with fittings added.

 

[Hondaracer2oo4]

Thanks guys. Found a deal on service entrance cable which I believe is 3 phase though. It is aluminum 5 conductor 2/2/2/2/4. It is gray service entrance cable. Could I use this instead of the MHf and not have to place it inside conduit inside the house ?

 

[Crazyjake8493]

The gray service entrance cable cannot be used underground even in conduit, since the conduit is a wet location. MHF is usually pretty cheap in the big box stores around here. Somewhere between $1-1.50 a foot last time I checked. I ran mine on a 60amp breaker since that's the biggest they had in the store, but if you want 90A they should be able to order you one, or a supply house might have it in stock.

Also on the issue of the panel, I would definitely go with main breaker instead of main lug. Usually cheaper too, and you can get a main breaker panel that will have 4 or 5 breakers included. And always go with a bigger panel than you think you will need!

 

[pattenp]

You if don't want to do conduit inside then splice SER to the MHF in a large junction box on the inside or outside of the wall where the SER needs to enter the house.

 

[Hondaracer2oo4]

I'll probably do the splice method. Thank you!

 

[sberry]

You can direct bury it too if cost is an issue, Have hundreds of feet of it.
I have some piped in 1.5 and it has some turns, it can be done but is really too small. Pulling a wire out is really harder than putting one in.

 

[sberry]

I'll probably do the splice method. Thank you!

Piping is not so hard, some can be external. Look around the neighborhood and see how they did these installs. No way I would want to splice unless I had to.

 

[Hondaracer2oo4]

Direct bury what? Why would you not want to splice it in a box? Running 2 inch conduit around a 220 year old crawlspace/basement would be no fun at all. If I could use large staples to staple up SER to the structure instead of messing with 2 inch pipe it would be much easier.

 

[pattenp]

The run of MHF underground to the garage can be direct buried, no conduit. But highly suggest using conduit.

 

[My Old Tools]

What pattenp said ^^^.

2-2-2-4 is aluminum mobile home feeder. Put a 90 amp breaker in your main panel. A 100 amp panel in the garage with a main breaker - 20 position panel would be good. Match your garage panel with your house panel so they use the same breakers. Ufer ground in garage. Check with you local electrical inspector for any considerations above and beyond NEC , permits required, etc.

That's what I did, plus a ground rod in addition to the ufer. Mine was about 130'. Off of the 100 amp panel I added a rotary phase converter and a small 3 phase panel as well. Square D QD panels in my place. Ran it in plastic conduit. You need to go 2.5".

 

[Hondaracer2oo4]

Yes I will definitely run the Mhf in conduit in the trench. I would just like to really get away from having to run conduit in the house. Any suggestions on splicing products?

 

[CNGsaves]

^ ^ ^ ^ Different path through yard between house and garage . . .
. . . SO . . . you do NOT have any splices.

Another 30 feet farther outside for MHF buried in conduit is little price to pay for not having to deal with any splices.

What would be length for outdoor buried IF you avoid the whole problem of splcing at the house ??

 

[sberry]

I bet I did a couple dozen of these direct burial, most well over 20 yrs now, probably closer to 30 and some over, never had one fail, never had someone call and ask wtf?

 

[bjcouche]

I'm also a huge fan of doing the entire run from one end to the other in conduit, which is how I did my shop feeder. However sometimes it's just not practical. For instance, if the breaker box is located on an interior wall, in the center of your house. Especially if you have to open up walls or have to try and fish conduit through studs.... I helped a friend run a feed to his shop and we ended up splicing the cable because it was nearly impossible to install the conduit where we needed to put it through walls, attic, etc. to get from the exterior of the house to the breaker box. SO if at all possible, run the whole thing in conduit. IF you need to splice, place the splice in a large box. Larger than the minimum required size as the wires are somewhat stiff. Some people use split bolts and tape to make the splice, but I prefer to use a terminal block. That way I don't have to tape it up and I can tighten the connection later without removing the tape..
Like this:
https://www.grainger.com/product/SQUARE-D-Power-Distribution-Block-2DD65
You'd need another single block for the ground, or a ground bar if you used a metal box.

 

[pattenp]

You can also use "splicer reducers" to splice the wire and tape up the connections.
http://www.google.com/url?sa=i&rct=...Q9oDj5HRRQoPvXQLFGtH_P2w&ust=1459283141778467

 

[larry4406]

You can also use "splicer reducers" to splice the wire and tape up the connections.
http://www.google.com/url?sa=i&rct=...Q9oDj5HRRQoPvXQLFGtH_P2w&ust=1459283141778467

Waking up this thread as I will be doing similar in the future. After taping these splicer reducers I assume its ok for them to all be in the same junction box without need to separate them (I suppose the wires could be "bent" to keep air space between the taped junctions).

I like the distribution block that was linked but it requires a single block for the ground or one could use a splicer reducer. Do they make a block with 4 terminals? The 4 terminal block would seem to be the ideal solution.

Lastly, my buried portion will be about 200' and the inside of house run will be about 50'. I would like to use SER inside the house to avoid retro fit of conduit in finished walls and attic. The junction box for SER to MHF would be at the house band board. What SER should I use and is the 2-2-2-4 still good at 90a for the total distance?

 

[pattenp]

Waking up this thread as I will be doing similar in the future. After taping these splicer reducers I assume its ok for them to all be in the same junction box without need to separate them (I suppose the wires could be "bent" to keep air space between the taped junctions).

I like the distribution block that was linked but it requires a single block for the ground or one could use a splicer reducer. Do they make a block with 4 terminals? The 4 terminal block would seem to be the ideal solution.

Lastly, my buried portion will be about 200' and the inside of house run will be about 50'. I would like to use SER inside the house to avoid retro fit of conduit in finished walls and attic. The junction box for SER to MHF would be at the house band board. What SER should I use and is the 2-2-2-4 still good at 90a for the total distance?

Taping the splices is fine with no separation. I use a wrap of 3M Temflex 2155 topped with a wrap of 3M Super 88.

250 feet is too far for #2 Al if your total load will be over 50 to 60 amps. To get up to 90A with about 3% voltage drop you'd need to use #2/0 Al. MHF does come in 2/0-2/0-2/0-1.

 

[larry4406]

Taping the splices is fine with no separation. I use a wrap of 3M Temflex 2155 topped with a wrap of 3M Super 88.

250 feet is too far for #2 Al if your total load will be over 50 to 60 amps. To get up to 90A with about 3% voltage drop you'd need to use #2/0 Al. MHF does come in 2/0-2/0-2/0-1.

Thanks PattenP!

 

[kutley]

I was told to take out my 2-2-2-4 CU SER. I had it ran from main panel from house to a sub-panel 65 ft away in a detached garage (buried in 1 1/2 Grey PVC).
The inspector came back out and told me it was ok.
Is there anything wrong with what I had? I don't want to burn down my house or garage. Initially the inspector told me it could not be buried.

 

[wyliesdiesels]

I was told to take out my 2-2-2-4 CU SER. I had it ran from main panel from house to a sub-panel 65 ft away in a detached garage (buried in 1 1/2 Grey PVC).
The inspector came back out and told me it was ok.
Is there anything wrong with what I had? I don't want to burn down my house or garage. Initially the inspector told me it could not be buried.

SER CANNOT and SHOULD NOT be buried. It is not rated for wet underground locations.

The issue isnt whether your house will burn down. Its that the wire will eventually fail...

 

[kutley]

Thanks for the info. Why would it fail? Does it get to hot? The SER wire I have is covered with grey plastic material and the wires are also coated with their own plastic. It seems like it would be ok.
What wire can I run without splicing? It will be hard to run PVC in house to main panel so wire in house will be unsupported by PVC.

 

[larry4406]

Thanks for the info. Why would it fail? Does it get to hot? The SER wire I have is covered with grey plastic material and the wires are also coated with their own plastic. It seems like it would be ok.
What wire can I run without splicing? It will be hard to run PVC in house to main panel so wire in house will be unsupported by PVC.

Right or wrong I used SER underground in a conduit to a detached prior garage. The electrician I got the cable from said the issue was the uncoated ground would corrode and fail. He had me pull a separate coated ground wire in the same conduit and the uncoated ground was not used. Knowing what I know now I will not do this again and will use proper cable. Not sure why the master electrician (who runs a reputable firm in my area) lead me down the wrong path.

 

[kutley]

Good information at least now I know why the SER is not suggested.
I guess I will run THWN #2 in PVC to the garage. If I do this would I need to run PVC in the house to the main panel? I am trying to get away from this.

 

[wyliesdiesels]

SER will fail underground because of water...

 

[kutley]

Even if it is sealed in PVC?

 

[pattenp]

PVC conduit underground will eventually get water in it from condensation. Individual wires of THHN/THWN are required to be in conduit. So if you use THHN/THWN for the entire run you need to run conduit from panel to panel. You can stop the conduit at the entry to the house and use a junction box and transition (splice) to SER for the inside run to the panel.