Garage Subpanel - Bringing Up to Code

[dda402]

I currently have SER cable in 2 inch conduit running 90 feet to a garage sub panel. I would like to replace it with 2-2-2-4 MHF or HHW-2. Which would be the better choice? I currently have a 200 amp panel in my house with a 70 amp breaker to the garage. The garage has a 100 amp main breaker panel. I have isolated the ground and have two ground rods seven feet apart. Any help with choosing the cable would be much appreciated. I have done a lot of home wiring but never a cable in conduit this length.

 

[dda402]

Their is a 12/2 uf wire in the same conduit for a outside garage light controlled at the house . Is that allowed by code?

 

[mm08822]

I would use xhhw as they are pulled as individual conductors (Straight, no twist, bundling). THHW can also be used, but xhhw is more durable insulation. Since you have 2"c, mhf can work as well.

The uf cable should be pulled out and re-pulled back in with the feeder so it doesn't harass you - IMO.

The problem with the UF in the feeder conduit is that it requires all conductors to be derated. Over 3 current carrying conductors (4-6), requires a derating to 80%. Your 70A cb in main panel provides the derate for #2 Al conductor ampacity.

 

[Movover]

I currently have SER cable in 2 inch conduit running 90 feet to a garage sub panel. I would like to replace it with 2-2-2-4 MHF or HHW-2. Which would be the better choice? I currently have a 200 amp panel in my house with a 70 amp breaker to the garage. The garage has a 100 amp main breaker panel. I have isolated the ground and have two ground rods seven feet apart. Any help with choosing the cable would be much appreciated. I have done a lot of home wiring but never a cable in conduit this length.

MHF should carry the RHH/RHW-2 rating. 2/2/2/4 with a 90A breaker would be fine. You can check to see if code in your area would permit 2/2/4/6 that what Ill be running where I don't have many 120v loads as its a little less per foot.

I don't have one but a box with about 10 lamps to screw in 2 prong adapters plug 8n to recepts. I get a helper and can map a house in short order especially if the legend is somewhat up to date. If I did this daily would be another matter but the occasional need,,, especially single house not worth it.

 

[Movover]

Their is a 12/2 uf wire in the same conduit for a outside garage light controlled at the house . Is that allowed by code?

No, there is only to be 1 means of power to the structure.

 

[slow]

Where is the power from that 12/2 coming from, the house or garage panel?

 

[dda402]

Power is from house panel.

 

[wyliesdiesels]

I currently have SER cable in 2 inch conduit running 90 feet to a garage sub panel. I would like to replace it with 2-2-2-4 MHF or HHW-2. Which would be the better choice? I currently have a 200 amp panel in my house with a 70 amp breaker to the garage. The garage has a 100 amp main breaker panel. I have isolated the ground and have two ground rods seven feet apart. Any help with choosing the cable would be much appreciated. I have done a lot of home wiring but never a cable in conduit this length.

SER is NOT permitted for use underground so its a good thing youre replacing it.

Why did you isolate the ground bus?

You shouldve isolated the neutral bus.

I don't have one but a box with about 10 lamps to screw in 2 prong adapters plug 8n to recepts. I get a helper and can map a house in short order especially if the legend is somewhat up to date. If I did this daily would be another matter but the occasional need,,, especially single house not worth it.

You posted this on the wrong thread

Their is a 12/2 uf wire in the same conduit for a outside garage light controlled at the house. Is that allowed by code?

Depends on where the power source originates from.

If garage, then its fine.

If house, then no bueno.

No, there is only to be 1 means of power to the structure.

Actually, it depends on where the source originates from.

 

[dda402]

Correction isolated the neutral not ground bus.

 

[Movover]

Actually, it depends on where the source originates from.

I learn every day here So I can have a switched light on my garage that is switched in the house as long as the power is fed from the garage panel ?

 

[mm08822]

MHF should carry the RHH/RHW-2 rating. 2/2/2/4 with a 90A breaker would be fine. You can check to see if code in your area would permit 2/2/4/6 that what Ill be running where I don't have many 120v loads as its a little less per foot.

Not with uf present in same conduit. need to derate.

 

[mm08822]

Their is a 12/2 uf wire in the same conduit for a outside garage light controlled at the house . Is that allowed by code?

I took this as a switch leg back to house, power originating from garage.

Might want to consider a 3 way set up and replace the 12-2 with 12-3 between house/garage, feed light/switch from garage ckt.

 

[Movover]

Not with uf present in same conduit. need to derate.

I Agree, that was added after I posted.

 

[sberry]

Whoops,,, see I posted in wrong thread above.

 

[dda402]

Just wanted to thank everyone who took the time to reply to my questions. Your information was very valuable to me and did answer all my questions. Thanks again.