AC disconnect and correct wiring for Micro inverter

[doctorman]

Total run is 90feet per line from the junction box to MSP + the trunk cable of the M215


so, to sum up, the whole plan

We have 2 roofs , upper and lower

top roof has 4 strings on it
15
15
13
13

lower roof has 2 strings on it
12
12

the plan is to bring 2 wires from each string L1 , L2 plus a Neutral and Ground per roof into the attic using #10 THWN-2 Wires
so
8 wires + N and G for top roof
4 wires + N & G for lower roof
in conduit around 35 feet run

from the attic go straight to the main service panel around 55' run
12 wires for 6 strings + N & G 14 wires of #10 Either THWN-2 or ROMEX
if I need conduit indoor for THWN-2 I might reconsider and do ROMEX
a 10/3 wire has 4 wires in it so for 14 wires total I can run 4 Romex 10/3 or 5 of 10/2



OR I can put a combiner box in the attic and just 1 Romex #4/3 to the main panel


would appreciate your help with the best option

You would also need to de-rate the amp capacity of those 12 cables (6 cable runs) if they are all in the same conduit.

[NewBostonConst]

You can't transition wire sizes without the protection of fuses or breakers...

What micro inverters are you using, many don't need a neutral or a ground...you could possibly get away with a single ground if required to the frames and rails.

[doctorman]

You can't transition wire sizes without the protection of fuses or breakers...

What micro inverters are you using, many don't need a neutral or a ground...you could possibly get away with a single ground if required to the frames and rails.

I am not transitioning wire size , going from HTWN-2 #10 to ROMEX #10

also the enphase trunk cable is 12AWG and no breaker needed in the junction box where I switch to the HTWN #10AWG

Enphase M215

so either I have to do ROMEX inside and out or HTWN-2?
Can I run ROMEX in conduit?
Can I run HTWN-2 without conduit indoor?

[NewBostonConst]

Total run is 90feet per line from the junction box to MSP + the trunk cable of the M215

OR I can put a combiner box in the attic and just 1 Romex #4/3 to the main panel

I am pretty sure you just ask about using a combiner box and #4/3, I am pretty sure that means you are asking if you can transition sizes. Also pretty sure I have seen combiner boxes without fuses or breakers....just trying to help, guess you can figure it out on your own.

[doctorman]

I am pretty sure you just ask about using a combiner box and #4/3, I am pretty sure that means you are asking if you can transition sizes. Also pretty sure I have seen combiner boxes without fuses or breakers....just trying to help, guess you can figure it out on your own.

oh... if I have a combiner box I will have breakers inside.

[ButchDeal]

Also pretty sure I have seen combiner boxes without fuses or breakers....just trying to help,

OP has a microinverter system so we are talking about an AC combiner. It would require breakers.

A DC combiner of TWO strings (3 with SolarEdge optimizers) would be possible without breakers or fuses.

[Mike90250]

Can I run ROMEX in conduit?

Maybe, but you may have to de-rate it per enclosed conductors

Can I run HTWN-2 without conduit indoor?

Very doubtful. That's what Romex was designed to accomplish, if it is permitted in your area. Not all areas permit romex.

[doctorman]

Spoke with tech at Enphase,
the data sheet for enphas eM215 Voltage drop calculation https://enphase.com/sites/default/fi...Vdrop_M215.pdf

so I am safe using #10 wire for 90' , to their understanding no need for conduit inside the house with THWN-2 unless the inpector asks for it

or I can do THWN and conduit to the inside of the attic combiner and a #4 Romex to the main panel

Total run is 90feet per line from the junction box to MSP + the trunk cable of the M215


so, to sum up, the whole plan

We have 2 roofs , upper and lower

top roof has 4 strings on it
15
15
13
13

lower roof has 2 strings on it
12
12

the plan is to bring 2 wires from each string L1 , L2 plus a Neutral and Ground per roof into the attic using #10 THWN-2 Wires
so
8 wires + N and G for top roof
4 wires + N & G for lower roof
in conduit around 35 feet run

from the attic go straight to the main service panel around 55' run
12 wires for 6 strings + N & G 14 wires of #10 Either THWN-2 or ROMEX
if I need conduit indoor for THWN-2 I might reconsider and do ROMEX
a 10/3 wire has 4 wires in it so for 14 wires total I can run 4 Romex 10/3 or 5 of 10/2



OR I can put a combiner box in the attic and just 1 Romex #4/3 to the main panel


would appreciate your help with the best option

[NewBostonConst]

THWN needs to be in concuit.

https://diy.stackexchange.com/questions/38134/can-i-run-thhn-wires-through-an-attic-without-conduit?rq=1

[doctorman]

THWN needs to be in concuit.

https://diy.stackexchange.com/questi...t-conduit?rq=1

thank you , Im not worried about rodents , but woud worry about NEC. so that settles it


NEC 300.3(A) prohibits THHN (or any other type of single wire save for a few exceptions such as single conductor MI and SE/USE, overhead wires, or an EGC) from being run outside some sort of raceway (conduit, surface raceway, cable tray, etc):

(A) Single Conductors. Single conductors specified in Table 310.104(A) shall only be installed where part of a recognized wiring method of Chapter 3.

[littleharbor]

Pulling Romex through conduit doesn't sound like any fun for anything more than a short or straight pull.

[doctorman]

Pulling Romex through conduit doesn't sound like any fun for anything more than a short or straight pull.

why would I do romex in conduit
in conduit will be thwn
in house will switch to romex
just have to calculate the cost see which is cheaper

Just found out the trunk cable I was sold was landscape , eventhough w eare installing portrait , meaning I lose a lot of V in the trunk cable
I reduced the damage by installing the junction box in the middle of the string and beefing it up to #8 HTWN wire and #4/3 Romex

[littleharbor]

[QUOTE=doctorman;n391817]

why would I do romex in conduit
in conduit will be thwn




Reread your post #18, your words, not mine.

[Ampster]

......
Just found out the trunk cable I was sold was landscape , eventhough w eare installing portrait , meaning I lose a lot of V in the trunk cable
I reduced the damage by installing the junction box in the middle of the string and beefing it up to #8 HTWN wire and #4/3 Romex

Great workaround. I had similar situation once and alternated panel hookups in two short cable runs to jbox. It was a waste of cable but I had more cable than time to get correct cable.

[NewBostonConst]

why would I do romex in conduit
in conduit will be thwn
in house will switch to romex
just have to calculate the cost see which is cheaper

Just found out the trunk cable I was sold was landscape , eventhough w eare installing portrait , meaning I lose a lot of V in the trunk cable
I reduced the damage by installing the junction box in the middle of the string and beefing it up to #8 HTWN wire and #4/3 Romex

It gets very hard for the next guy when you keep switching cable sizes. Someone might see the bigger wire and think they can increase the breaker size, but in reality when done and the other end of the wire it is small it is dangerous. In this situation it could cause a house fire. Upsize the THWN to match the Romex if possible. I am sure the cost is not worth a life. Correct me if I am wrong.