I'm looking to upgrade my panel in my garage (circa 1979) from 60 amp to 100 amp. Currently, the garage panel is fed directly from the meter so it is wired as a main panel. The house main panel is 100 amp and is fed from the meter as well. The meter is 36 feet away from the garage panel and #4 aluminum travels though conduit from the meter to the ground, a couple of inches into the ground the conduit stops and wire is buried without conduit until it gets to the garage. Once it gets to the garage a small conduit is used from the ground until it gets into the exterior wall and the conduit stops. I've read that others have used aluminum mobile home feeder cable in this forum, is that an option for me to get to 100 amps? If so, what gauge? Should I use conduit all the way, or just bury it like it currently is? Is there any other options? Thanks in advance!
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Upgrading garage panel from 60A to 100A
- Thread starter cloneman
- Start date
Bib Overalls
Well-known member
2-2-2-4. You actually need 2-2-4 but I don't think they make it. Simply remove one wire. You can direct bury MHF but the conduits need to run 18" to 24" into the ground with a sweep. You need to talk with your power company about the meter base. They will send out a field engineer if you ask. To make your connection you will have to lift the meter. They will have specific requirements for originating two services from the same meter. You may have to change out the meter base. A lot of changes to the code in the past 40 years.
Last edited:
teamextreme
Well-known member
Something doesn't sound right with this setup. Where is the main disconnect? It sounds to me like both panels, garage and house, are fed separately from a main disconnect, in which case they should both be installed as subpanels with the ground and neutral not bonded together. Either way, you definitely need 4 conductors, not 3 as suggested above. They stopped allowing 3-wire feeds to separate buildings (except for a single MWBC) a couple code cycles ago. Others will post up regarding the use of MHF, but I believe the 2-2-2-4 is only good for 90 amps. It's personal preference regarding conduit use or not. Not using it requires a deeper trench. Using it means more work to install conduit and pull the cable through, but a shallower trench. If you're using a trencher, not a concern. I would use conduit.
Bib Overalls
Well-known member
There have been a number of arguments here about the amperage capacity of aluminum 2-2-2-4 and 2-2-4-6 MHF. Some say 90 amps and some say 100 amps. I note that Southwire rates it's #2 conductor MHF at 100 amps.
http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheetOEM47
I would use a 100 amp breaker and not worry a bit. Others may feel more comfortable with a 90 amp breaker.
http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheetOEM47
I would use a 100 amp breaker and not worry a bit. Others may feel more comfortable with a 90 amp breaker.
alfredeneuman
Well-known member
That Product Data Sheet has a note at the bottom:
"Dwelling - For units, conductors shall be permitted at listed ampacities as 120/240-volt, 3-wire, single-phase services and feeders"
The Code allows this ONLY for services and feeders carry the entire load of the house which in this case not applicable.
"Dwelling - For units, conductors shall be permitted at listed ampacities as 120/240-volt, 3-wire, single-phase services and feeders"
The Code allows this ONLY for services and feeders carry the entire load of the house which in this case not applicable.
theoldwizard1
Well-known member
Also, conduit is required all the way to the breaker box.You can direct bury MHF but the conduits need to run 18" to 24" into the ground with a sweep.
In other words, MHF is only allowed outside of a conduit below ground.
Hint, use Schedule 80 conduit as you enter the ground. Anything less will not stand up to a string trimmer.
Something doesn't sound right with this setup. Where is the main disconnect? It sounds to me like both panels, garage and house, are fed separately from a main disconnect, in which case they should both be installed as subpanels with the ground and neutral not bonded together. Either way, you definitely need 4 conductors, not 3 as suggested above. They stopped allowing 3-wire feeds to separate buildings (except for a single MWBC) a couple code cycles ago. Others will post up regarding the use of MHF, but I believe the 2-2-2-4 is only good for 90 amps. It's personal preference regarding conduit use or not. Not using it requires a deeper trench. Using it means more work to install conduit and pull the cable through, but a shallower trench. If you're using a trencher, not a concern. I would use conduit.
The main disconnect is apparently the meter. The meter is grounded. Three wires go from the meter to the house. Three wires go from the meter to the garage. I'm wanting to get it up to the current code. Do I need to add a 200A panel below the meter and make it the main panel and send four wires to the house and four to the garage? What gauge do I need for the garage?
pattenp
Well-known member
In my opinion it's best to have a main disconnect panel serving the 2 feeds, one to the house and one to the garage. With that type setup the feeds to the house and garage will be 4 conductors from the main disconnect panel. The main disconnect panel is served by 3 wires from the meter. As far as the wire size goes you really need to check with your local electrical inspector to know what they will allow for the size amp feeds that you want from the main disconnect.
theoldwizard1
Well-known member
In my opinion it's best to have a main disconnect panel serving the 2 feeds, one to the house and one to the garage. With that type setup the feeds to the house and garage will be 4 conductors from the main disconnect panel. The main disconnect panel is served by 3 wires from the meter. As far as the wire size goes you really need to check with your local electrical inspector to know what they will allow for the size amp feeds that you want from the main disconnect.
Always good advice from pattenp, especially the last part !