Do I have this right? Class T fuse on 4/0 feed to two 2/0 feeds to inverter?

[Onehand]

Credit to Hedges.

Below figures based on Hedges computations and I suspect on 6500EX inverters, or other, not quite as efficient as the 6000XP at 93%, as per spec sheet.

2 6000XP 6000 watt max charge/output draw EACH. (plus momentary surge, not included below)

6-8 foot 4/0 wire length.

If 6500EX/other: 4/0 wire. 12000W / 85% efficiency / 48V minimum x 1.25 margin x 1.12 ripple factor = 411A. Use a 400 Class T?

If 6000XP: 93% efficiency, 12000W / .93% efficiency / 48V minimum x 1.25 margin x 1.12 ripple factor = 376A. Use a 400 Class T?

2 -3 foot runs: 2/0 wire, 200A Class T on each 2/0 to inverter?

Looks like I purchased a 300A for no reason, thinking it would be ok for the 4/0 run.

Am I close?

 

[chrisski]

If 6500EX/other: 4/0 wire. 12000W / 85% efficiency / 48V minimum x 1.25 margin x 1.12 ripple factor = 411A. Use a 400 Class T?

Does your 4/0 have the ampacity for this amperage? The NEC chart I have below does not even get to 300 amps.

I also don’t get why the 2/0 is fused to 200 amp? Same thing. The ampacity chart I have below does not reach 200 amps.

This is my ampacity chart based off an older version of NEC code. Wire spec sheet can trump this.

 

[Onehand]

No idea, I'm flying IFR here. Could that chart be for AC only? I know allot of people are using the arrangement I have posted.

At least the 2/0 gets close@90C.

 

[hwy17]

You can run your 300 for the 4/0 and probably never blow it.

Adding 2x 200 would be most correct. Some might yolo it without.

 

[Onehand]

Temco says the 4/0 is good to 440A. I have a bunch of this in the machine shop this is why I chose it.

TEMCo WC0308 Welding Cable - 4/0 AWG 20 ft - Black

temcoindustrial.com

 

[chrisski]

Temco says the 4/0 is good to 440A. I have a bunch of this in the machine shop this is why I chose it.

TEMCo WC0308 Welding Cable - 4/0 AWG 20 ft - Black

temcoindustrial.com

I think that cable will be fine, unless it’s inspected, than I don’t know.

What I’m learning with the inspection I got is seems the inspector wants wiring to the NEC chart and not ampacity of wire.

The town can be challenged on the inspections, but it’s easier to replace a few feet of wire than do the appeals process.

 

[Onehand]

I think that cable will be fine, unless it’s inspected, than I don’t know.

What I’m learning with the inspection I got is seems the inspector wants wiring to the NEC chart and not ampacity of wire.

The town can be challenged on the inspections, but it’s easier to replace a few feet of wire than do the appeals process.

Ya, know what you mean. When I was installing and going through inspections, some guys were reasonable and others, you got the feeling they were just trying to justify their existence while walking on water. Thankfully I have scaled the business back and no longer have to endure the county.

I really have to wonder how "up to snuff" inspectors are in regard to these systems and DC voltages in general. Perhaps someone will chime in with their assessments.

 

[chrisski]

Mine was the town inspector wanted 1 AWG wire for 100 amps installed in a UL approved inverter and UL approved SCC that came from the factory wired with 4 AWG from the SCC to the inverter.

Personally, I’m glad I did not do the install so the contractors could deal with it. Dealing with permitting and plans would have taken me years.

 

[Onehand]

Allot of it is about the dollar. When I was doing commercial, light industrial jobs it took a year or better to get through all the approvals and get up and running. Of course the local gas and go, wawa or whatever convenience store around the corner, goes from dirt to open for business in 6 months or less. Its not what you know, it's...

 

[Axotopia]

Just passing on what i learned from forum member pvgirl on one of my posts on conductor battery size: the Temco welding cable rating may be for conductor in free air.

Not sure if you any of your conductors are in conduits, if you do, may need to look at the NEC table 310.16. Looks similar to the chart posted by chrisski

Also need to verify 75c rating due temperature limitations at terminations per NEC 110.14(C)

If you need the system inspected, the NEC dictates. This includes NEC recognized conductor types if the inspector checks.

I'm still confused and learning, so maybe some of experienced members can chime in.