Garage Subpanel -100ft away from main-

[Danestar]

I have been researching this over and over and finally had to ask an electrician and want to verify this.

I am trying to install a 125A Sub panel to run everything in the garage, compressor, garage AC/Furnace (yes separate from home), washer, dryer, lights, outlets, garage door etc etc. Currently everything spans the length of the house to main. I am planing to remodel the garage and want the controls closer. My question is from what I am told I can get away with a 6/3 service wire from main to sub romex style running under the house (4ft platform in rear due to yard grade). Does this sound funny to anyone and or right?

 

[FltEngCPO]

I'm looking for similar info. I'm 100' away from my meter to the shop. I got a call back from a licensed electrician (code required) that wants $1400 to run the wire, put in a 100A sub-panel, (plus two electrical outlets and a light to meet code) plus wants an additional $500 to trench the 70' (30' already has schedule 40 PVC under the driveway from initial build). Does this seem extreme in price?

 

[Alchymist]

I have been researching this over and over and finally had to ask an electrician and want to verify this.

I am trying to install a 125A Sub panel to run everything in the garage, compressor, garage AC/Furnace (yes separate from home), washer, dryer, lights, outlets, garage door etc etc. Currently everything spans the length of the house to main. I am planing to remodel the garage and want the controls closer. My question is from what I am told I can get away with a 6/3 service wire from main to sub romex style running under the house (4ft platform in rear due to yard grade). Does this sound funny to anyone and or right?

#6 (assuming copper) is good for 60 amps, and 100 feet is about the limit.

Try this:
http://www.csgnetwork.com/wiresizecalc.html

 

[Mmfh]

For a 125 amp panel, shouldn't you run a #4 or even better a #2. 100 amp main breaker in the sub panel and 100' to it, I'd say at least #4 or better. That's just what I'd do.

 

[pattenp]

To the OP.. if this feed is totally inside your home from main to the sub-panel then I would use aluminum SER the whole way. How many amps do want at the sub-panel? #2 AL SER can give you up to 90A if not run within insulated walls or floors.

 

[pattenp]

For the full 125A you need to use #1 copper or #1/0 aluminum.

For 100A you need #3 copper or #1 aluminum. This all based on 75C.

 

[Danestar]

Thank you everyone for the info.

To the OP.. if this feed is totally inside your home from main to the sub-panel then I would use aluminum SER the whole way. How many amps do want at the sub-panel? #2 AL SER can give you up to 90A if not run within insulated walls or floors.

The house is platform style but the area under the house isn't big enough for basement and or anything other than free space and dirt. It is in Northern CA so I don't think running the service wire under the house will be an issue. I am just happy I don't have to trench and or run thru a very tight attic. My real concern is the black-widows which are all over the place in the back yard... I assume I will see a few under there...

I guess my concern is the cost of 100' service wire is insane... But I still need to do it but looking for alternatives like going 6/3. Aluminum cost was a relief compared to copper.

 

[pattenp]

Yep the aluminum is a third or less of the cost of copper. Buy some bug bombs to throw under the house a day or so before you crawl under there to pull the wire.

 

[Danestar]

Yep the aluminum is a third or less of the cost of copper. Buy some bug bombs to throw under the house a day or so before you crawl under there to pull the wire.

Does the Alum service wire come complete or do I need 3 runs of SER wire? Does it appear like the photo above.

Regarding the creatures (Bwidows) I have found that Wasp Spray (the kind that shoots 10-15ft) kills them instantly and just picked up a case. Spider spray is worthless against them.

 

[pattenp]

SER cable comes as pictured. When you go to get it specify 4 wire (2 hots, 1 neutral, 1 ground). SER also comes in 3 wire, but you don't want 3 wire SER.

If you do use aluminum wire be sure to use aluminum wire antioxidant paste on the wire ends at the connections.

 

[Gary S]

For the full 125A you need to use #1 copper or #1/0 aluminum.

For 100A you need #3 copper or #1 aluminum. This all based on 75C.

This sounds right to me. I ran #2 copper to my 100amp box in my garage because Menards didn't carry #3, and their #2 was cheaper than #3 anywhere else. And, my wire run is well under 100 feet.

 

[Socophreak]

Just make sure you are using the antioxidant paste as said above. If not you will have tons of corrosion which will lead to fire.

 

[Aceman]

Just make sure you are using the antioxidant paste as said above. If not you will have tons of corrosion which will lead to fire.

That's not true, installation instructions taken right from Southwire's site:

Terminating Conductors
Proper termination of the conductors is directly related to system reliability. It is imperative that properly rated devices are used. This became apparent in the 1960s when aluminum wiring was terminated to devices rated for copper conductors. The result was unreliable electrical systems. AA-8000 series aluminum paired with UL listed terminations has resulted in proven reliable residential and commercial installations for over 30 years. What follows is some history and best practices for aluminum conductor termination.

Aluminum Connectors – With the advent of AA-8000 series aluminum alloy, listed aluminum
terminations are as reliable as copper. When aluminum was first used for commercial and
residential wiring in the 1960s, manufacturers used the same EC 1350 electrical grade aluminum used by utilities. The same properties that make this alloy great for transmission applications
made it a poor choice for the commercial terminations of the times.

The solution would come in two parts:
1) A new aluminum alloy that possessed the properties to perform well in commercial and
residential terminations was needed. Southwire was the first to introduce such an alloy in
1968 and called it triple e™ (now called AlumFlex,™ emphasizing its ease of installation). Later
the National Electrical Code® required the use of 8000 series aluminum alloy and Underwriters
Laboratory (UL) required that all aluminum building wire, with the exception of single-rated
USE, be manufactured with AA-8000 series aluminum.
2) Listed connectors were another important factor in reliable aluminum conductor terminations.
In the 1960s, terminal lugs were not tested or designed for use with aluminum wire. Today’s
listed connectors are designed and tested for use with AA-8000 series aluminum alloy. This
ensures complete compatibility of materials, such as brass set screws instead of steel.
When terminating aluminum conductors, there are several practices one should be aware of to ensure a quality connection that will remain trouble free.
1) Always use a connector that is listed for use with aluminum wire.
2) The following is recommended but not required. Always follow the connector manufacturer’s
instructions
a. The surface of the conductor should be wire-brushed to break any aluminum oxide
barrier leaving a clean surface for the connection.
b. The use of anti-oxidant compound, joint compound, is not required unless the
connector’s manufacturer requires it. However, the use of a listed joint compound is
always a good practice.3) Always tighten set-screw type connectors to the manufacturer’s recommended torque.
4) Most importantly, do not re-torque the terminations as part of routine maintenance. As
with copper conductors, repeated tightening of any set-screw connections can result in the
eventual “biting” through the conductor causing the termination to fail.

 

[Alchymist]

Just make sure you are using the antioxidant paste as said above. If not you will have tons of corrosion which will lead to fire.

That's not true, installation instructions taken right from Southwire's site:

..... What follows is some history and best practices for aluminum conductor termination.

When terminating aluminum conductors, there are several practices one should be aware of to ensure a quality connection that will remain trouble free.
....... However, the use of a listed joint compound is
always a good practice.

CYA statement in red.....most inspectors want to see the anti-ox paste on any aluminum....would never install aluminum without it. Even some of the large crimp-on al connectors come pre-loaded with paste.