New Enphase Field Wireables

[pv_n00b]

The EGC requirement in the TC-ER cable would rule out the 2-wire cable your searching for...

2014 NEC

Sounds like it's a catch 22. Just because a manufacturer specifies that a 3rd party cable can be used with their connector does not mean one is available or listed for that use. I doubt that they had a specific product in mind when they wrote that.

 

[Zee]

In the 2014 NEC this was added to 690.31:

(D) Multiconductor Cable. Multiconductor cable Type
TC-ER or Type USE-2 shall be permitted in outdoor locations
in PV inverter output circuits where used with utility-interactive
inverters mounted in locations that are not
readily accessible. The cable shall be secured at intervals
not exceeding 1.8 m (6 ft). Equipment grounding for the
utilization equipment shall be provided by an equipment
grounding conductor within the cable.

In 2017 that was changed to:
Multiconductor Cable. Jacketed multiconductor cable
assemblies listed and identified for the application shall be
permitted in outdoor locations. The cable shall be secured at
intervals not exceeding 1.8 m (6 ft).

So the 2014 NEC specifically allows TC-ER limited use and 2017 if it is identified for the application. There is also article 336 which puts a lot of limits on TC use. Before 2014 690 did not specifically address multi-conductor cable and I don't know if anyone was trying to use TC.

There was a problem with people wanting to use non-TC in trays in the PV array and 690.31(C)(2) was added in 2014 to allow the use of PV Wire in cable trays.

What's the driver for wanting to use TC anyway? Just cost or are their other advantages?

Driver was cost but mainly the minimum order size of 300m=1000'.
about $900/1000'.
TC-ER is about $400/1000'..........and i can have 100' cut.

Anyways i bought some TC-ER, found two-conductor, no EGC as desired, flat cable, and used it on a job. Works fine in connectors and compression strain relief fittings.
BUUUUT......two thing bugs me:
1. the black outer jacket is thinner than the Type DG stuff Enphase sells.
2. Enphase specs 19 strand CU....... and while i see no reason why, they call the shots no? (TC ER is 7 strand)

I'll bite the bullet.

 

[Zee]

I work for a non profit solar installer, and our region uses Enphase equipment almost exclusively for our residential projects for a whole bunch of reasons, some of which may not translate perfectly into the for profit world... so your mileage may vary.

I really like the Q Cable in the right scenario. In general we do lots of small systems (most of our jobs are 1 branch). We have mostly been using it where we have 2 arrays on the same branch that aren't located in the same roof plane, and eliminating the Junction Box on the array located farthest away from the roof penetration. I like the fact we are almost center feeding the second array, I like the fact I get to eliminate a junction box, wire nuts, crimps, and pulling a second mod during inspections in AHJ's that want to look in J Boxes, I also like the fact that my crews get a chance to practice with MC4 crimps which they don't see every day. In general it does seem slightly faster to install field wirables vs a J box in my experience, but it's not huge.

It also makes installing systems that are just slightly over 1 branch a little less irritating... I'm building a single roof plane 17 mod job tomorrow. With M250's we may have seriously considered not installing a MaxBranchLength+1 design and just dropping a module because the juice for one extra mod may not be worth the squeeze of upsizing conduit, pulling the extra conductors and barely fitting 6 wire nuts into one SnapNRack Junction box. With field wirables I can take this same 17 mod design and break it up into a branch of 8 and a branch of 9 and land both into the same junction box really easily and not burn extra drops. In fact, with IQ and Field Wirables the only reason I still carry 3/4" EMT hardware is for service on existing systems, training, and the real off chance that we need to install a 3 branch job.

There are a couple other small advantages we've found which may not be applicable in the For Profit world:

We work with a large volunteer base and job training organizations, because we don't have to land EMT into a second J box it makes our conduit runs just a little easier for our crews, who may be teaching folks who have never been on a roof before how to bend pipe in a little less precise application. Also in general, the fewer wire nuts and bare copper crimps we can run is generally a better situation with less opportunity for error.

Our experience may not translate perfectly into the For Profit world, those are just my observations! I wont use them every job, but I'll keep them on my van in case I find a good use for them.

Thank you. Agreed. The point is to avoid j boxes, wire nuts.