Enphase IQ Combiner 4 Output Wire Size

[gridsolar]

I noticed that spec sheet for the Enphase IQ Combiner 4/4C lists #10-2/0 AWG for wire size range on the main lug combined output. What if my system is only 1 branch on a 20A breaker and I'm wiring #12 on the wire input. Can I put a #12 on the main lug output as well? In theory, only up to 20A would be outputted anyways, so wiring a #12 on the output seems fine to me. I'm wondering why the spec sheet has it start at #10 when they allow up to #14 on the input side, considering the system is only 1 branch with max circuit current < 20A.

 

[Carultch]

I noticed that spec sheet for the Enphase IQ Combiner 4/4C lists #10-2/0 AWG for wire size range on the main lug combined output. What if my system is only 1 branch on a 20A breaker and I'm wiring #12 on the wire input. Can I put a #12 on the main lug output as well? In theory, only up to 20A would be outputted anyways, so wiring a #12 on the output seems fine to me. I'm wondering why the spec sheet has it start at #10 when they allow up to #14 on the input side, considering the system is only 1 branch with max circuit current < 20A.

The product is only tested for the range of #10 as the minimum size. It's impractical to make a universal lug that can accept all possible wire sizes, so it is common that you'll see minimum sizes like this.

Likely, Enphase wanted to give flexibility for sizes up to #2/0, and the only lugs they could find that were commercially available, would only allow as small as #10. The underlying intent of the product is that you'll combine multiple microinverter circuits, so it is much more likely you'll want a size between #8 and #3 as the output wire for this product's intended use.

A work-around is to install a local section of #10 Cu to connect to the terminal in question, and then splice it to a #12 Cu output wire. If it were my choice in your situation, I'd only do that if I screwed up, and didn't anticipate this minimum size. I'd specify #10 Cu if I spotted this issue in advance.

 

[PWDickerson]

Don't try to put a #12 conductor in a terminal rated for #10 or larger conductors. There is a reason it is rated like that.

 

[jaggedben]

Nobody in the solar industry uses 12awg on either side of an Enphase combiner. Partly because of voltage drop/rise and partly because of rooftop temperature adders and derating. 10awg minimum is what I've always seen and spec'd myself.

I'm not saying you couldn't possibly use 12awg to the roof if you really wanted to, I'm just explaining why you're probably the first person to ever complain about the spec on those combiner lugs.

 

[gridsolar]

The product is only tested for the range of #10 as the minimum size. It's impractical to make a universal lug that can accept all possible wire sizes, so it is common that you'll see minimum sizes like this.

Likely, Enphase wanted to give flexibility for sizes up to #2/0, and the only lugs they could find that were commercially available, would only allow as small as #10. The underlying intent of the product is that you'll combine multiple microinverter circuits, so it is much more likely you'll want a size between #8 and #3 as the output wire for this product's intended use.

A work-around is to install a local section of #10 Cu to connect to the terminal in question, and then splice it to a #12 Cu output wire. If it were my choice in your situation, I'd only do that if I screwed up, and didn't anticipate this minimum size. I'd specify #10 Cu if I spotted this issue in advance.

Thanks for the detailed explanation!

 

[gridsolar]

Nobody in the solar industry uses 12awg on either side of an Enphase combiner. Partly because of voltage drop/rise and partly because of rooftop temperature adders and derating. 10awg minimum is what I've always seen and spec'd myself.

I'm not saying you couldn't possibly use 12awg to the roof if you really wanted to, I'm just explaining why you're probably the first person to ever complain about the spec on those combiner lugs.

For a small system of ~2.5 kW DC on a small roof, it is very possible to use 12 awg even considering voltage drop + rooftop temp adder. This is actually the case for many new ADUs in California that need to meet the Title 24 requirement.

For this, I'm surprised I'm the 'first person' to ask about this. I'm not complaining, I'm clearly trying to understand why they allow 12awg on input and not output.

 

[ggunn]

Nobody in the solar industry uses 12awg on either side of an Enphase combiner. Partly because of voltage drop/rise and partly because of rooftop temperature adders and derating. 10awg minimum is what I've always seen and spec'd myself.

I'm not saying you couldn't possibly use 12awg to the roof if you really wanted to, I'm just explaining why you're probably the first person to ever complain about the spec on those combiner lugs.

Beat me to it. Most solar installers carry a buttload of #10 on their trucks and use it whenever the minumum size is #10 or smaller.

 

[BackCountry]

For a small system of ~2.5 kW DC on a small roof, it is very possible to use 12 awg even considering voltage drop + rooftop temp adder. This is actually the case for many new ADUs in California that need to meet the Title 24 requirement.

For this, I'm surprised I'm the 'first person' to ask about this. I'm not complaining, I'm clearly trying to understand why they allow 12awg on input and not output.

I tried to find the document, but somewhere out there is a PV design manual that shows the rationale behind #10. We simply do not use #12, everything is #10 minimum. I remember someone pre wired for micros with two 12/2 NM-B romex cables on a job, and we had to get a variance to accept it.

Typically with a temp correction of .88, conduit fill correction of 1.0, #10 is capable of 30.8A -- which means 13 or less IQ8+ is no problem, you're actually good up to 20 micros in that scenario.

We carry #12 and #14 for relocating loads in a BESS install, but otherwise we start at #10 and carry all the way up to #2 CU. Then we switch over to AL and stock up to 4/0. We're always in a state of battle over how much wire we carry.

 

[jaggedben]

I tried to find the document, but somewhere out there is a PV design manual that shows the rationale behind #10. We simply do not use #12, everything is #10 minimum. I remember someone pre wired for micros with two 12/2 NM-B romex cables on a job, and we had to get a variance to accept it.

Typically with a temp correction of .88, conduit fill correction of 1.0, #10 is capable of 30.8A -- which means 13 or less IQ8+ is no problem, you're actually good up to 20 micros in that scenario.

We carry #12 and #14 for relocating loads in a BESS install, but otherwise we start at #10 and carry all the way up to #2 CU. Then we switch over to AL and stock up to 4/0. We're always in a state of battle over how much wire we carry.

Back when the temperature adders in 310.15(B)(3)(c) were more strict it was near impossible to have 12awg be rated for the roof, especially if you wanted to pull more than one circuit in a conduit. Standardizing on 10awg meant you could grab it off the truck and be compliant without double-checking every installation.