Can I use this wire?

[donb108]

A couple of years ago hurricane Ida ripped my breaker panels off the wall, so I had the replacements installed on the inside of the house. At the same time, we wired for a whole house generator and a future solar system. I took my best guess on wire sizes and had them all installed at the same time. The generator worked out great, and now it's time for the solar system.

I was planning to use the EG4 6000XP and ~20KWH of batteries. After re-reviewing my power needs, I realized the EG4 12000XP might be a better pick, but the wire size might not make it. We installed two runs of 4/4/4/6 aluminum SER (for AC_in and AC-out), which is rated for 65 amps (75 amp @90 degC). The 12000XP has max AC out of 50 amps. However, it's breaker is rated for 100 amp, and the installation manual says to use 3 AWG copper, minimum, which is rated for 100 amps. Can I use the 4/4/4/6 SER, or ???

 

[ScrodusGargleRotten]

You would need 2 other breakers. AC in and out

I would never use aluminum personally

 

[sumpower]

If you are following the NEC then you are required to use the 60° column when using conductors smaller than #1, the 60° column in the table for ampacity of conductors says the #4 Aluminum is rated for 55 amps.

 

[Supervstech]

Sorry, but no.
The 100A minimum transfer abilities keep you from running that load.
Sorry.

I would pull it, and run 1/0-1 SER...ALUMINUM, OR #3 copper.
How long a run are we talking?
Is there conduit?

 

[timselectric]

You can use the existing wiring, as long as you protect it from being overloaded.
This will limit your passthrough amount. Only you can know if 50a is enough.

 

[donb108]

You would need 2 other breakers. AC in and out

You mean to add breakers in-line? I was kinda considering doing that anyway. I like having a convenient means of disconnect, right next to the equipment.

I would never use aluminum personally

Not my first choice either, but at the time, prices were pretty high. One run for the generator and two for solar were > $2200 in aluminum. As I recall, copper was way more. It just wasn't in the budget.

If you are following the NEC then you are required to use the 60° column when using conductors smaller than #1,

Hmm, good to know, I've never heard that. By the way, the ampacy chart I usually use doesn't have a column for 60 deg; wonder why?

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

How long a run are we talking?
Is there conduit?

About 75-90 ft each. No conduit, it's all in the attic. 200' of 1/1/1/3 aluminum is ~$500. 200' of 3/3/3/5 copper is ~$2000 Prices from https://nassaunationalcable.com/

You can use the existing wiring, as long as you protect it from being overloaded.

Hmm, good point. So, I can use the existing wire if I size the breakers appropriately. I think this may be the same as @SomethingAppropriate was suggesting. I was hoping I could start with this wire and maybe up-size later, after getting some experience with it.

 

[Daddy Tanuki]

You mean to add breakers in-line? I was kinda considering doing that anyway. I like having a convenient means of disconnect, right next to the equipment.


Not my first choice either, but at the time, prices were pretty high. One run for the generator and two for solar were > $2200 in aluminum. As I recall, copper was way more. It just wasn't in the budget.


Hmm, good to know, I've never heard that. By the way, the ampacy chart I usually use doesn't have a column for 60 deg; wonder why?

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

About 75-90 ft each. No conduit, it's all in the attic. 200' of 1/1/1/3 aluminum is ~$500. 200' of 3/3/3/5 copper is ~$2000 Prices from https://nassaunationalcable.com/


Hmm, good point. So, I can use the existing wire if I size the breakers appropriately. I think this may be the same as @SomethingAppropriate was suggesting. I was hoping I could start with this wire and maybe up-size later, after getting some experience with it.

or run a second run of the same and connect them with buss bar system. personally i do not like the idea of aluminum either.. too many trailer fires when I was younger for the folks living in trailers in my area, but thats when they first started using aluminum wires

 

[Backyard]

If you are following the NEC then you are required to use the 60° column when using conductors smaller than #1, the 60° column in the table for ampacity of conductors says the #4 Aluminum is rated for 55 amps.

What code requires all sub #1 to follow the 60° column? If this is true, why would the NEC have 75° and 90° columns for sub #1 wires?

 

[Supervstech]

What code requires all sub #1 to follow the 60° column? If this is true, why would the NEC have 75° and 90° columns for sub #1 wires?

The other columns are for derating formulas, and commercial use where 75 and 90C connections are available.
If you check, the breakers are rated for a max 75C, so as long as BOTH ends you are connecting to allow 75C, you can use it at that rating.

 

[Backyard]

The other columns are for derating formulas, and commercial use where 75 and 90C connections are available.
If you check, the breakers are rated for a max 75C, so as long as BOTH ends you are connecting to allow 75C, you can use it at that rating.

I'm familiar with the connections rating limiting the wire rating. But it has nothing to do with gauge

 

[ScrodusGargleRotten]

I'm familiar with the connections rating limiting the wire rating. But it has nothing to do with gauge

what?

 

[Daddy Tanuki]

for gods sake stop being cheap and just do it right... or end up in up in smoke. i have rewired several times due to my lack of knowledge. its a part of the learning process... that or pay a pro to unscrew your efforts.

 

[Backyard]

what?

The temperature rating of the wire is limited to the lowest rated part of connector the wire is attached too. So if the connector is only 75° rated then the wire while may be 90° it has to follow the 75° column in the NEC amp rating chart

 

[ScrodusGargleRotten]

The temperature rating of the wire is limited to the lowest rated part of connector the wire is attached too. So if the connector is only 75° rated then the wire while may be 90° it has to follow the 75° column in the NEC amp rating chart

Yes, but the temps is directly related to wire gauge.

 

[Daddy Tanuki]

oh crud, jsut double up, spend the money and learn how to get around asinine rules... yes one set of wires will not be enough. double up and move on with the project.

 

[donb108]

or run a second run of the same and connect them with buss bar system

Could I use something like a Polaris connector on each end; 2 x 4 AWG in and 1 AWG out?

Amazon.com

 

[Backyard]

Yes, but the temps is directly related to wire gauge.

Code?

 

[teal95]

I think doubling up is legal by code for anything bigger than #2?

 

[OzSolar]

Dave Gordon and Mike Holt have several videos on this. You may have to click around to few of them to get the answers.

 

[donb108]

Could I use something like a Polaris connector on each end; 2 x 4 AWG in and 1 AWG out?

Wait, I thought that was against the rules, like, 1 in and 2 out was OK, but 2 in and 1 out was bad. Something about the current not being shared equally on both conductors.

 

[Daddy Tanuki]

Could I use something like a Polaris connector on each end; 2 x 4 AWG in and 1 AWG out?

Amazon.com

I am not a code guy, but @timselectric can answer that... i just know if you double up the cables and land them on a solid copper busbar you will carry the load. Tim can tell you whats legal.... I personally know I would not give to f-s as long as my family will wake up in the AM.

 

[timselectric]

I think doubling up is legal by code for anything bigger than #2?

Close
Parallel feeders are only allowed for #1/0 and larger.

 

[Daddy Tanuki]

Close
Parallel feeders are only allowed for #1/0 and larger.

thanks for the quick reply.... I do not know US codes, so I ask people like Tim the hard questions... at the OP, you should too.

 

[ScrodusGargleRotten]

Code?

common sense.

That is why you are not using 10 awg i presume?

 

[Backyard]

common sense.

That is why you are not using 10 awg i presume?

Code ≠ common sense