1

First time running overhead drop from home to unattached garage, main panel more than able to support service... need 60' to 70' run. I am familiar with NEC but not a professional. I have done home wiring before, put in main panels and sub-panels, hot tubs, etc... with oversight in the past by a contractor friend so I know all is ok.... even passed inspection :)

Sect 225, 338, 340 and other codes regulate type of overhead outside cable (i.e. weather resist, UV, voltage rating...) Understand height above roof, service head, drip loop, securing with Gav stranded line between building and drop to garage.... Also looking at voltage drop calc trying to keep within 3% (5%max) drop I can do.

Anyway, I am burnt out as I am trying to figure out which type of insulated overhead cable to use. Home depot has nothing. Even though I will be using 60 amp, I will be running 100 amp service and I recall in NEC I thought all overhead drops had to be a min of 100 amp, and underground service min 200 amp. In past have used CU, but thinking of now using AL which I know on the chart will effect my size wire. 220vac run.

Sorry for long winded, never been here before.... just need some part number to something to figure out the type of outside drop wire to use. Using 4 (3 + ground)conductors as this is a sub-panel, and not a drop from a power pole...

2
  • 2
    Consumer big-box stores do not do a good job supplying the necessary gear for overhead lines. You'll need to go to an electrical supply house for that, which is a good idea anyway for stuff generally. There's no 60/100/200A minimum for overhead lines. 3% is not anywhere in Code, it's a wire salesman thing. Your power will come in at 240V+ anyway so you can have over 8% drop and still be > 220V. Anything this long and big you want aluminum. They won't even make copper quadplex, no one would buy it. Oct 15 at 23:55
  • We don't take replies offline around here, so make sure to check back for inquiries and answers Oct 16 at 0:30
2

You want an overhead quadruplex cable

First off, the cable you want for this isn't going to turn up at a big-box store, since it's generally only used for overhead service drops. Instead, you'll need to visit the local electric supply house and get a "Chola" cable -- this is a 6-6-6-6 aluminum service drop cable, and good for almost 70A as you can use the 90°C column in table 310.20 for this run. While you're there, you'll need to figure out the sag and tension for this cable to make sure its at a sufficient height that nobody runs into it: putting the lowest point of the cable's arc 12' above ground is generally adequate on a house-lot, but the mast height and extra cable length required to get there vary depending on your climate.

The rest of this run, then, will be handled using 4AWG Al XHHW-2 in 1.5" RMC masts, along with Burndy AGSKIT2 splice kits, dual-rated split bolts and pipe grounding clamps, service wire holders and weatherheads, and some 6AWG or 8AWG bare copper for jumpering the messenger to the mast at each end. The garage end will need more of that bare copper anyway to provide a grounding electrode conductor to the garage's ground rods (a pair of them driven 8' deep and 6-8' apart), and you'll also need a 100A or 125A, 24-space or 30-space, main breaker panel that has its bonding screw removed and a grounding bar fitted to serve as the garage's panel.

Finally, at the house, you'll want to have a small (6x6x4" is fine) NEMA 1 pullbox and a LB + nipple + locknuts where the feeder mast enters the house, assuming its located remotely from the breaker panel that is. A 4-4-4-4 SER cable with some 14-4 insulated mechanical splice connectors or a 3-pole 14-4 to 14-4 UL 1953 splicer/distribution block to make the hookups in the box can then be used to bring power out to the mast-exit box.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.