Battery Cables

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eds

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I have been tasked with a solar job, with battery backup. Fortress cabinet to house up to 4 batteries, we are using (2) fortress 5.4 batteries. Engineer has called for 1 1/4 pvc to house the cables from cabinet to inverter. 600v battery cables are being used, along with a 6 bonding wire. Conduit size seems inadequate unless I house them in separate conduits. Won’t I experience heating if they are in separate conduits. I would like to use NMLT due to height constraints. Inverter is a Sol-Ark 5kW.

Any input would appreciated, I do have a RFI into the engineer.

Thanks
 
eds said:
I have been tasked with a solar job, with battery backup. Fortress cabinet to house up to 4 batteries, we are using (2) fortress 5.4 batteries. Engineer has called for 1 1/4 pvc to house the cables from cabinet to inverter. 600v battery cables are being used, along with a 6 bonding wire. Conduit size seems inadequate unless I house them in separate conduits. Won’t I experience heating if they are in separate conduits. I would like to use NMLT due to height constraints. Inverter is a Sol-Ark 5kW.

Any input would appreciated, I do have a RFI into the engineer.

Thanks
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Assuming this is on the DC side, that is not an issue.
 
2/0 cables, will likely order them on line, on the dc side. 1 positive, 1 negative. What code section will apply to this dc side?
 
Interesting, if I run the bonding conductor with the battery cables, it fits. If I run the bonding conductor separate, I can only fill to 31%. Was using rhh insulation for the battery cables
 
A few comments:

- While Chapter 9 Table 1 doesn't say so, I would think that any two conductors in a conduit should add up to no more than 31% of the conduit area. As it doesn't make sense that adding more conductors would reduce problems with the pull. Unless there's some weird physics I'm not aware that the 3rd smaller conductor actually helps keep the 2 large ones from jamming or whatever?

- Chapter 9 Table 5 has dimensions for both RHH* and RHH, with the latter being much larger in a given conductor size. What's the difference? The calculator Larry linked to seems to refer to them as RHH (uncovered) and RHH (covered), respectively.

- Any reason not to use regular THHN/THWN-2 for these battery connections? They are smaller than RHH*, and (2) 2/0 are then under 31% of the inner area of Schedule 40 PVC 1-1/4".

Cheers, Wayne
 
I had planned on ordering the cables with the rings already crimped on. I couldn’t find the actual installation designation, so I plugged in rhh as a worst case scenario. I may be wrong but I thought battery cables were a finer strand than thhn, like welding cable. Again I may be out in left field on this
 
Check the actual diameter if you can. I have been burned on this before, running battery cables to a generator in conduit, and the wire was larger than the type I compared it to. Also, if you are getting rings installed, which is a good idea, will they fit through the conduit?
 
Save yourself the headache and run 2” pvc, the cost difference isn’t that much. I have noticed the engineers spec the minimum conduit size to be run. The installers almost always run larger conduit.
 
acrwc10 said:
Save yourself the headache and run 2” pvc, the cost difference isn’t that much. I have noticed the engineers spec the minimum conduit size to be run. The installers almost always run larger conduit.
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I tell our designers when they want to be chentze on conduit fill, I know the code says it will fit but I'd like to see you do it......
 
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