CU feeder and AL feeder tap

[hhsting]

I have copper feeders 6 sets of (4#500 kcmil, 1#250G) fed from 2000A fuse going into a trough and the tap conductors are going to be AL 3 sets of (4#500AL, 1#400G). Is their anything in NEC 2014 which would say the tap conductors have to be copper? Also would AL feeder tap does not comply with any NEC 2014 code sections?

 

[tom baker]

110.3 B
Your last sentance is confusing.
AL is fine per the tap rules.
As the conductors are in parallel, all the parallel conductors per phase have to be tapped. Before you ask Ilsco makes a parallel tap.

 

[augie47]

Al taps are permitted. Tap rules apply and method must address dissimilar metals. Bottom line for plans review purposes: Compliant.

 

[LarryFine]

You've got my blessing.

 

[Carultch]

Perfectly OK to mix conductor materials when making a tap, provided your connector type allows it. Your connector type would have to be rated for use with both materials, and it would have to separate the two conductors.

Examples that would comply are as follows:
1. Insulation piercing connectors
2. Insulated tap connectors (Polaris blocks)
3. Split bolts with a separator bar
4. Multi-wire lugs that have separate openings
5. Using the otherwise-vacant lug on a breaker that has capacity for multiple wires.

Examples that would not comply are as follows. To build a tap in these situations, you need to match the material of both the feeder and tap.
1. Standard split bolts
2. Single opening lugs (what I call "snowman lugs"), that are rated for two wires. Even if rated for both conductor materials, it is not rated for both conductor materials together.

 

[augie47]

answered.... closed