Enphase QD Cable

S

solarken

NABCEP PVIP
Location
Hudson, OH, USA
Occupation
Solar Design and Installation Professional
Anyone install Enphase commercial inverters that use the QD 3-phase cable? If so, what type of cable do you use for extending the home run to jbox or to disconnect? I know there is raw QD cable (without the QD connector drops) but looks like my suppliers only sell in 300m reels and not cut to length. Are the field assembled QD connectors compatible with a different wire type that is readily available at local electrical supply house? Or do you generally just order QD connector cable with an extra drop or 2 and use a short length of the extra cable to get it into a jbox for transition to THHN? Thnx.
 
solarken said:
Anyone install Enphase commercial inverters that use the QD 3-phase cable? If so, what type of cable do you use for extending the home run to jbox or to disconnect? I know there is raw QD cable (without the QD connector drops) but looks like my suppliers only sell in 300m reels and not cut to length. Are the field assembled QD connectors compatible with a different wire type that is readily available at local electrical supply house? Or do you generally just order QD connector cable with an extra drop or 2 and use a short length of the extra cable to get it into a jbox for transition to THHN? Thnx.
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Once your wiring is no longer exposed in open air as part of the array, you can run it in any wiring method that is allowed for AC circuits in general, suitable for the environment of the wiring. It could be NM cable (i.e. Romex), or THWN-2 wire in a raceway (usually EMT inside a building), or metal clad cable, or anything else.

The QD cable is needed for its exposure to the outdoor environment and sunlight resistance, and for the application of paralleling microinverter outputs (which either has to be done as separate branch circuits, or with brand-specific listed equipment for doing so).
 
solarken said:
Anyone install Enphase commercial inverters that use the QD 3-phase cable? If so, what type of cable do you use for extending the home run to jbox or to disconnect? I know there is raw QD cable (without the QD connector drops) but looks like my suppliers only sell in 300m reels and not cut to length. Are the field assembled QD connectors compatible with a different wire type that is readily available at local electrical supply house? Or do you generally just order QD connector cable with an extra drop or 2 and use a short length of the extra cable to get it into a jbox for transition to THHN? Thnx.
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I typically just mount a j-box within reach of the Q cable. I've never found it to be impractical or worth doing something else. Do you have a situation where that isn't feasible?
 
electrofelon said:
I typically just mount a j-box within reach of the Q cable. I've never found it to be impractical or worth doing something else. Do you have a situation where that isn't feasible?
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I'm not sure yet, have an L-shaped array to install on a membrane roof that already has the conduit penetration installed and fixed, so not really sure if I can install the center fed connector close enough to where the jbox will be so that a short trimmed piece will reach. Just thought it would be nice to have options for longer distance if needed.
 
Carultch said:
Once your wiring is no longer exposed in open air as part of the array, you can run it in any wiring method that is allowed for AC circuits in general, suitable for the environment of the wiring. It could be NM cable (i.e. Romex), or THWN-2 wire in a raceway (usually EMT inside a building), or metal clad cable, or anything else.

The QD cable is needed for its exposure to the outdoor environment and sunlight resistance, and for the application of paralleling microinverter outputs (which either has to be done as separate branch circuits, or with brand-specific listed equipment for doing so).
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Thanks, I understand that but asking for the case where the open air distance might be longer than a trimmed piece of connectorized QD cable.
 
Pretty sure the single-phase Q-cable is just sunlight resistant TC-ER. I would be surprised if the QD cable isn't the same thing with an extra conductor. But I don't have a scrap of it around to double check for you.

If you don't want to run conduit all the way, another option would be UF. Probably cheaper to use UF and an off-the shelf j-box than TC-ER and the Enphase connectors. Some people hate working with UF, so it's really a matter of preference.
 
Carultch said:
It's type DG cable, which is a black PVC jacket wrapped around two #12 Cu THWN-2 wires.
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So I've been curious about that, where is in the NEC is that shown as an approved wiring method?
 
electrofelon said:
So how can we use it?
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The DG cable is part of the listed assembly of microinverter and cable. So you can use them together. If you're not using the micros - or something else that's listed together with the cable - then you can't use the cable.

A better code citation is 690.31(4). And maybe it's more 90.7 than 110.3.
 
We ended up buying the whole reel of QD cable just to run little whips from our center taps to nearby junction boxes. Still have lots left over if you need some shorter lengths. In retrospect though, I realized that #8awg TCER would probably fit in the field wireable connections used for the Center Taps, and that would have been a smarter decision perhaps.

Instead, from our Center Taps we ran to QD cable and then to nearby Junction Boxes where we transitioned to #6awg TCER, and then transitioned to THHN/Conduit once we left the array boundary. This made for LOTS of connections. You gain vRise pretty quick running any sort of lenght on the 12awg QD cable though. In our application we really felt like we needed to jump directly from the QD to #6awg.
 
am1954 said:
We ended up buying the whole reel of QD cable just to run little whips from our center taps to nearby junction boxes. Still have lots left over if you need some shorter lengths. In retrospect though, I realized that #8awg TCER would probably fit in the field wireable connections used for the Center Taps, and that would have been a smarter decision perhaps.

Instead, from our Center Taps we ran to QD cable and then to nearby Junction Boxes where we transitioned to #6awg TCER, and then transitioned to THHN/Conduit once we left the array boundary. This made for LOTS of connections. You gain vRise pretty quick running any sort of lenght on the 12awg QD cable though. In our application we really felt like we needed to jump directly from the QD to #6awg.
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Thanks for the reply. For this project I ended up ordering 2 extra drops on the QD cable, which should give me the whips needed to reach the jbox, where I will transition to 10AWG THHN. Crazy that they only sell the large reel of raw QD.
 
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