importance of earthing a rack battery and its cabinet ??

[pvgirl]

1) Do the 1/0 support the same specs as the 1AWG (ie 600 volts /200 amps)?
2) If so, can I use the 3/8" ends on the 5/16 lugs in the inverter?
3) If not, can I use a second set of the 84in 1AWG from my breakers to the battery, or is that going to cause overheating?

Neither 1/0 or 1 AWG(these are different wire sizes) are rated for 200 amps by the electric code(NEC). For 200 amps you will need 3/0 or 4/0 AWG conductors, 2 1/0 AWG in parallel would also be acceptable. Ref: NEC 2020 310.16 Ampacities of Insulated Conductors in Raceway, Cable, or Earth (Directly Buried) You should use a NEC acctable conductor type like MTW, RHW-2, etc.

Lug size should match the bolt size

1 AWG is not large enough to run in parallel.

 

[ksmithaz1]

Thanks for all the help and insight:

While on the subject of breakers and wires. Perhaps you can provide a better answer that the short responses I get from Signature Solar to the following concern:

Two sets of 84in 1 AWG Battery to Inverter Cables | Black and Red wiring came with my units. This runs a tad too short for my plans.

On the SS site, I'm see the 96in 1/0 AWG Battery to Inverter Cables | Black and Red

Three questions:

1) Do the 1/0 support the same specs as the 1AWG (ie 600 volts /200 amps)?
2) If so, can I use the 3/8" ends on the 5/16 lugs in the inverter?
3) If not, can I use a second set of the 84in 1AWG from my breakers to the battery, or is that going to cause overheating?

Here's what I've got so far, but I need to put the cables in 1-1/4" flex tubing, and the run falls too short with single 84" lines. If things won't overhead, I'm thinking I can pick up from the breakers with full-length 84" 1AWG and make this work. What do you think?
Perhaps I should just switch to the 2/0 cable suggested by Will Prose as shown here: https://www.amazon.com/Welding-Battery-Flexible-Terminal-Connectors/dp/B01M35S1J2

Open to all nature of guidance. Thanks.

This isn't really that hard. Read the NEC tables attached. Use the 60 column unless you are sure all your connectors and wire is rated above 60C.

Don't run your battery cables in a raceway or conduit, run them free to air. You will want a soft cable like a welding cable. You will want a breaker or fuse inline that matches the wire/ampacity you decide on between your battery cabinet and your inverter. I'd run 2 4/0 welding cables from the battery to a 600A or better bus block on the wall, independently fused at 300A. That covers you to all the way to the bus bar for 600A / 6 LifePower4 batteries at max output.

Then bring #2 THHN from the bus block on the wall thru 100A battery/flip breakers up to to the inverters. Again I'd run the THHN free to air, it's nice and stiff, you can run a simple tie down or two on the back board as needed. The soft cable will keep you out of trouble if you roll the cabinet around a little from time to time.

So 2 fuse blocks, and 2 breakers. This also gives you a shut-off point if you need to disconnect a single inverter for some reason.

 

[ksmithaz1]

I had to re-engineer this when I swapped out inverters, So I'm not thrilled, but something like this, bring the 4/0 into a fuse then into the bus bar, then from the bus bar I'm paired over to the inverters. Unfortunately I was unable to put my inverters on the same wall, they are 90 degrees. Make sure all your battery cables of the same polarity are reasonably close to the same length. ie from the bus bar your red cables to each of the inverter cabinets should all be the same. This means you may need to create a loop if one is closer to the bar than the other.

 

[pvgirl]

This isn't really that hard. Read the NEC tables attached. Use the 60 column unless you are sure all your connectors and wire is rated above 60C.

Don't run your battery cables in a raceway or conduit, run them free to air. You will want a soft cable like a welding cable. You will want a breaker or fuse inline that matches the wire/ampacity you decide on between your battery cabinet and your inverter. I'd run 2 4/0 welding cables from the battery to a 600A or better bus block on the wall, independently fused at 300A. That covers you to all the way to the bus bar for 600A / 6 LifePower4 batteries at max output.

Then bring #2 THHN from the bus block on the wall thru 100A battery/flip breakers up to to the inverters. Again I'd run the THHN free to air, it's nice and stiff, you can run a simple tie down or two on the back board as needed. The soft cable will keep you out of trouble if you roll the cabinet around a little from time to time.

So 2 fuse blocks, and 2 breakers. This also gives you a shut-off point if you need to disconnect a single inverter for some reason.

For systems that being are being permitted and/or inspected, running wire free to air, and using most welding wire, are going to be violations. Also a 100 amp battery breaker is going to be too small for 6500 watt inverter.

 

[ksmithaz1]

For systems that being are being permitted and/or inspected, running wire free to air, and using most welding wire, are going to be violations. Also a 100 amp battery breaker is going to be too small for 6500 watt inverter.

Dunno about inspections everywhere, but I asked around, and I'm pretty sure you can run it free to air here, but you are supposed to have to have covers everywhere the wire is exposed or something. Cable sizes go up dramatically in conduit/raceway. 6500/48 = 136, so yes 150A breaker. FA is still #2 @ 75C, but that's silly, Just get some 1/0 for the bus interconnect, length matters too, the longer you go the fatter the wire you want, but these should all be 10ft or less.

If you want 600A from your batteries in conduit you are at some really expensive cable. Keep in mind when you add conductors to a conduit or raceway you have to reduce the ampacity when you get to 4. The LP4 battery cabinet is not really designed for conduit.

 

[rmharrington]

Neither 1/0 or 1 AWG(these are different wire sizes) are rated for 200 amps by the electric code(NEC). For 200 amps you will need 3/0 or 4/0 AWG conductors, 2 1/0 AWG in parallel would also be acceptable. Ref: NEC 2020 310.16 Ampacities of Insulated Conductors in Raceway, Cable, or Earth (Directly Buried) You should use a NEC acctable conductor type like MTW, RHW-2, etc.

Lug size should match the bolt size

1 AWG is not large enough to run in parallel.

The 1 AWG wire in question is labeled at 600V, but says nothing about amps. Note that I am only driving two eg4 ll 48 volt batteries at this time. Will eventually up two three. Also, the lugs in the inverts are 5/16, not 3/8. Please consider this response, then extend your advice. Every time it looks like I understand this stuff, things get confusing all over again.

The following statement is via email conversation with Signature Solar tech crew.
"Those cables are built to safely handle the max amps (160A @ 48V when max PV charging 8000W) that a single inverter could potentially push or pull from the battery at any given time."

 

[rmharrington]

This isn't really that hard. Read the NEC tables attached. Use the 60 column unless you are sure all your connectors and wire is rated above 60C.

Don't run your battery cables in a raceway or conduit, run them free to air. You will want a soft cable like a welding cable. You will want a breaker or fuse inline that matches the wire/ampacity you decide on between your battery cabinet and your inverter. I'd run 2 4/0 welding cables from the battery to a 600A or better bus block on the wall, independently fused at 300A. That covers you to all the way to the bus bar for 600A / 6 LifePower4 batteries at max output.

Then bring #2 THHN from the bus block on the wall thru 100A battery/flip breakers up to to the inverters. Again I'd run the THHN free to air, it's nice and stiff, you can run a simple tie down or two on the back board as needed. The soft cable will keep you out of trouble if you roll the cabinet around a little from time to time.

So 2 fuse blocks, and 2 breakers. This also gives you a shut-off point if you need to disconnect a single inverter for some reason.

Just to forward the same question I posted elsewhere. I need lots of input.

The 1 AWG wire in question is labeled at 600V, but says nothing about amps. Note that I am only driving two eg4 ll 48 volt batteries at this time. Will eventually up two three. Also, the lugs in the inverts are 5/16, not 3/8. Please consider this response, then extend your advice. Every time it looks like I understand this stuff, things get confusing all over again.

The following statement is via email conversation with Signature Solar tech crew.
"Those cables are built to safely handle the max amps (160A @ 48V when max PV charging 8000W) that a single inverter could potentially push or pull from the battery at any given time."

 

[pvgirl]

@rmharrington what is the reason/requirement for the battery wire to be in conduit?

 

[rmharrington]

@rmharrington what is the reason/requirement for the battery wire to be in conduit?

It's part of the local code. I'm doing Off Grid, but still want to be on track incase I decide to expand in the future

 

[pvgirl]

It's part of the local code. I'm doing Off Grid, but still want to be on track incase I decide to expand in the future

Yeah to follow the code we have to use the right size wire for being in conduit. For a 6500 watt inverter, max amps is going to be 6500 watts output / 85% efficiency / 44 minimum volts, gives us 173 amps max draw. 1 AWG is only rated to 130 amps in conduit. With a 200 amp breaker we should consider wire with at least a 200 amp rating such as 4/0. If you don't want to make your own cables, there are companies who will make custom cables with right sized ends, using listed wire, such as: https://www.batterycablesusa.com/0000-gauge-awg-ul-battery-cable-with-ends

 

[ksmithaz1]

It's part of the local code. I'm doing Off Grid, but still want to be on track incase I decide to expand in the future

So your local code requires 48v battery cable in conduit? I know the high voltage DC cable from your panels if inside in conduit is supposed to be in METAL conduit per NEC. I'd start digging thru your local codebook, because you are about to bolt your battery rack to the floor to run 2" rigid steel back into a box somewhere, and fan it out to the inverters. Nothing wrong with that, it's just going to be more expensive, and require a bit of extra engineering.

 

[pvgirl]

@ksmithaz1 I'd love to know the code section that exempts battery wires form the requirement of being run using a NEC chapter 3 wiring method.

 

[Quattrohead]

I think code for high voltage DC is anything over 48 or 50 volts, I'm not exactly sure which but there is an unspoken allowance up to 60 odd volts to allow for various battery systems.
But basically if you are following code any high voltage DC will have to be in some kind of metal conduit.

 

[rmharrington]

Yeah to follow the code we have to use the right size wire for being in conduit. For a 6500 watt inverter, max amps is going to be 6500 watts output / 85% efficiency / 44 minimum volts, gives us 173 amps max draw. 1 AWG is only rated to 130 amps in conduit. With a 200 amp breaker we should consider wire with at least a 200 amp rating such as 4/0. If you don't want to make your own cables, there are companies who will make custom cables with right sized ends, using listed wire, such as: https://www.batterycablesusa.com/0000-gauge-awg-ul-battery-cable-with-ends

Nice information and link. Looks like a solution. I'm currently trying to make do with the exposed wire as shown in the attached image. I''ll wire the subpanel to run minor lighting, a frig, and a microwave just to get things up and working enough to satisfy myself that the project warrants additional cash input. Once pass this stage, I'll rework the battery wiring, and will likely go with a pre-assembed unit as described on the link.

They claim the eg4 6500 is capable of outputting burst as high as 8000 watts.

You're great with this stuff. Will I be safe to run a temp ground from the battery rack direct to my home's grid grounding bar? And the same with the ground from the solar array?

 

[rmharrington]

So your local code requires 48v battery cable in conduit? I know the high voltage DC cable from your panels if inside in conduit is supposed to be in METAL conduit per NEC. I'd start digging thru your local codebook, because you are about to bolt your battery rack to the floor to run 2" rigid steel back into a box somewhere, and fan it out to the inverters. Nothing wrong with that, it's just going to be more expensive, and require a bit of extra engineering.

How many k does your home pull in a day?

 

[pvgirl]

Since

You're great with this stuff. Will I be safe to run a temp ground from the battery rack direct to my home's grid grounding bar? And the same with the ground from the solar array?

I'd put a junction box or use and existing junction box, near the inverter, and add a ground bus bar, to tie all grounds at your inverters together. If you have a grid connection to the inverter you can use that ground conductor to connect to the ground system, other wise run a dedicated ground wire to your main panels ground bus.

 

[webbbn]

This table table appears to define the classes of DC circuits. Is that right?

 

[rmharrington]

Since

I'd put a junction box or use and existing junction box, near the inverter, and add a ground bus bar, to tie all grounds at your inverters together. If you have a grid connection to the inverter you can use that ground conductor to connect to the ground system, other wise run a dedicated ground wire to your main panels ground bus.

I'm liking your help. Two questions concerning the above:

1) If I tie the grid to the inverter and the grid goes down, will the inverter backfeed the grid.

2) I had planned to install a subpanel using a generator style slider to switch back to the grid if necessary (Thinking of using something such as this

ACANORA Generator Interlock Kit for ITE, Murray, Siemens, Gould 150 and 200 Amp Panels, 1 1/4 Inches Spacing, Silver.​

So, if I used something like the Acanora, would the dedicated ground from the main to the sub still provide the necessary equipment bonding?

​

 

[rmharrington]

@ksmithaz1 I'd love to know the code section that exempts battery wires form the requirement of being run using a NEC chapter 3 wiring method.

Sometimes it isn't about code; just depends on what the local inspectors want.

 

[pvgirl]

I'm liking your help. Two questions concerning the above:

1) If I tie the grid to the inverter and the grid goes down, will the inverter backfeed the grid.

2) I had planned to install a subpanel using a generator style slider to switch back to the grid if necessary (Thinking of using something such as this

ACANORA Generator Interlock Kit for ITE, Murray, Siemens, Gould 150 and 200 Amp Panels, 1 1/4 Inches Spacing, Silver.​

So, if I used something like the Acanora, would the dedicated ground from the main to the sub still provide the necessary equipment bonding?

​

1) No, when the grid goes down the inverter will isolate the grid input, and not feed any power back.

2) Yeah the ground from the main to the sub panel is good enough, using the sub panel is a good choice for centralizing your grounds on this system.