Need advice on EG4 6500EX wiring

[donb108]

I'm re-working my breaker panels this summer (now), and planning to add a hybrid solar system later this year. I'd like to install any wiring going from the inverter(s) to the breaker panels now, while everything is open and accessible. I'm using this diagram (pg 55 of the user manual) as a reference.






It looks like I could use a single 6/3 romex for AC-input and the same for AC-output. But, the EG4 manual (pg 7) recommends using #4 AWG. Apparently, 4/3 romex is rare or non-existant, so I'll have to use individual conductors in conduit (~90ft run, through attic). After some quick online shopping, #4 copper THHN + conduit comes to about $1600, and 2-2-2-4 aluminum URD is about $475.

Aluminum is looking attractive, but Signature Solar strongly recommends against using aluminum. Also, it looks like the EG4 6500 terminals might not be big enough for 2 AWG, and aren't rated for AL/CU. Other forum users have shown me methods to jump from aluminum to copper at the inverter (another $50-$100 in parts), so maybe that's not a problem.

There are lots of scary examples of aluminum wiring gone bad, but electricians seem use it a lot. Is aluminum really to be avoided and are there another alternatives to consider? Any suggestions appreciated.

 

[BentleyJ]

There are reducing crimp lugs that reduce from #2 wire to a #4 wire equivalent sized pin that would fit the EG4 lug. Not sure if these are available for aluminum wire. Ideally something that is solid copper, tin plated with noalox or equivalent inside the barrel to accept the Al wire. I'm curious if it exists, will do a couple of online searches.

 

[BentleyJ]

Here is an Al compression lug for #2 wire, the pin diameter is 6.1mm. Will this fit the EG4 mechanical lug?

 

[BentleyJ]

ZPTS2 - Aluminum Compression Pin Adapter - 2 AWG - Tan

ZPTS/ZPTO compression pin adapters are made of aluminum with an electro tin-plated finish for enhanced durability. They are designed for use with molded case circuit breakers, panel board equipment, and meter sockets. They provide reliable termination of both aluminum and copper conductors while...

www.ferrulesdirect.com

helps if you attach the link

 

[kuranaga]

I'm re-working my breaker panels this summer (now), and planning to add a hybrid solar system later this year. I'd like to install any wiring going from the inverter(s) to the breaker panels now, while everything is open and accessible. I'm using this diagram (pg 55 of the user manual) as a reference.


View attachment 99609



It looks like I could use a single 6/3 romex for AC-input and the same for AC-output. But, the EG4 manual (pg 7) recommends using #4 AWG. Apparently, 4/3 romex is rare or non-existant, so I'll have to use individual conductors in conduit (~90ft run, through attic). After some quick online shopping, #4 copper THHN + conduit comes to about $1600, and 2-2-2-4 aluminum URD is about $475.

Aluminum is looking attractive, but Signature Solar strongly recommends against using aluminum. Also, it looks like the EG4 6500 terminals might not be big enough for 2 AWG, and aren't rated for AL/CU. Other forum users have shown me methods to jump from aluminum to copper at the inverter (another $50-$100 in parts), so maybe that's not a problem.

There are lots of scary examples of aluminum wiring gone bad, but electricians seem use it a lot. Is aluminum really to be avoided and are there another alternatives to consider? Any suggestions appreciated.

you should not use Al if terminals are not spec for Al... it can only go wrong!

What you could do is to use intermediary distribution blocks (like Mersen FSPDB2A) that are specified for Cu AND Al. Then you wire a copper pigtail (1ft or so) from your inverter to the block, then run the long wires as Al from the FSPDB2A to the other end, where you do the opposite with another triplet of FSPDB2A. Will cost you around $100 for each side for the blocks. Just do the cost calculation and always use Al terminal paste to prevent oxydation.

https://ep-br.mersen-prod.accelance.net/sites/mersen_br/files/DS-FSPDB-Series-UL-1059-Finger-Safe-Power-Distribution-Blocks-Mersen.pdf

Your cross section also depends on the length of the wires. 90ft doesn't sound that much for me - use voltage drop calculator! I did not put your values in but seems to me 6x3 could be fine.

 

[donb108]

I did not put your values in but seems to me 6x3 could be fine.

Yes, I thought the same, #6 AWG THHN is rated for 65 amps @75 degC. Good, I needed about 55 amps (6500 / 120 = 54.167 amps).

But NM-B (romex) uses the 60 degC column, which de-rates it to 55 amps. Maybe that's why they recommend #4 AWG? That's why I started looking at aluminum.

Cerrowire Resources - Ampacity Charts

Ampacity is the maximum current that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Cerrowire's ampacity chart helps calculate the load requirement for a circuit.

www.cerrowire.com

 

[acdoctor]

I would use the aluminum. I would also terminate at the inverter end with a couple of 2 circuit breaker panels of pull out disconnects. Then copper to the inverters. I would want disconnecting means at the inverters regardless.

 

[donb108]

you should not use Al if terminals are not spec for Al... it can only go wrong!

Absolutely correct. When I asked Signature Solar, they didn't actually say the terminals are not AL/CU rated, they strongly recommended against aluminum and never answered the question. So, without verification, I have to assume they are not AL/CU rated.

What you could do is to use intermediary distribution blocks (like Mersen FSPDB2A) that are specified for Cu AND Al.

Right again, and you're in good company, two other people have recommended the same approach.

I would also terminate at the inverter end with a couple of 2 circuit breaker panels of pull out disconnects. Then copper to the inverters.

Another vote for aluminum/interconnect/copper pigtails.


@Kornbread had the same suggestion (post #19 of the thread); shows interconnects and breakers.

AL/CU splice?

With copper prices going way up, I'm considering using aluminum for a 75 foot run through my attic, then splicing on copper for the drops to the panels at each end. I found 2-2-2-4 URD at Nassau on clearance. It looks like I can use it without conduit, installing similar to romex. Is this...

diysolarforum.com

Will this fit the EG4 mechanical lug?

I checked with Richard at S-Solar, he thinks #4 AWG will just fit. But they're pretty caution about anything aluminum; doubt they would be OK with it.


This all assumes I can use aluminum in the first place, but S-Solar strongly recommends against using it at all; what gives, did I misunderstand?

 

[timselectric]

Aluminum is fine, it just takes extra care at the connection points. Only connect to rated lugs or terminals, and use an Oxidation inhibitor.

 

[LywWyr]

Aluminum feeders are used all the time in residential wiring.

 

[kuranaga]

cheapest option for you:

https://www.aliexpress.com/item/3256804203682671.html

will cost you like $10 for the splice lugs + the crimping tool.

then splice Al onto a Cu pigtail