Splicing sub-panel feeder cable.
 

I am installing a sub-panel in my attached garage. I am using a GE 100 amp main breaker panel as the sub. I will use a 60 amp breaker in my 200 main to feed this sub.

I can get a deal on SER 4-4-4-6 Aluminum for less than a dollar a foot that I would like to use as the feeder. The only hook is is in 50 foot coils and I need about 85 feet.

Is there any problem installing a junction box in my attic and splicing to get the length I need? I have looked at my NEC 2008 and can not find any prohibition. The JB would be accessible.

Assuming it is OK, what is the best method to make this splice?

The JB would be accessible. That's the only kicker, get a good sized pvc box, some split bolts and rubber/friction tape, regular electrical tape and go to town

Pre-insulated Polaris connectors are expensive, but are easier than split bolts.

Thanks for the replies.

Jim P, the Polaris connectors are $12+ each vs $5 for a pair of split bolts plus some DR(rubber) tape. Do you really think for that for the 4 connections I will have to make that they are worth the expense. Plus I will have to order them on line and pay shipping as none of the supply houses in my area carry them.

The Polaris are a labor saver for sure. Strip the conductor and insert into the connector and tighten to proper torque.

With the split bolts you still strip the connectors and then tighten the nut. Now you spend considerable time wrapping rubber tape around an irregular shape with sharp edges until fully covered. After all that then you add a couple of layers of plastic tape. And don't even think about needing to strip off the tape if you need to remake a connection.

Got lucky on this one. Went to pick up the cable yesterday and the guy asks, "Would you like to have 100 feet instead of 2 50's?" No brainer here and I am out the door with 100 feet of SER AL 4-4-4-6 for $80. This was an electrical contractor retiring and was selling off his stock. The cable had a fair amount of dust on it but it blew off on the way home.

So, no splice in the attic. Thanks to all who responded with advice.