Renogy 3000W incorrect wire size on installation manual?

[ee.va]

Hi All,

I've been skimming through the Renogy 3000w inverter charge manual and it states the following:



I followed up by checking with the NEC Amperage Tables. 4/0 is well below the threshold of 300A only rated at 230A at 75 degrees C.



Even the 12V 200Ah battery from Renogy rated 4/0 cable for 230A.




My gut feeling is off on this one, would appreciate any expertise regarding this situation.

 

[sunshine_eggo]

There are higher grade ratings, 90°C can handle 260 and 105°C (marine grade) can handle more - 200°C silicone wire even more.

According to this website, their 4/0 can go 445 (near the bottom of the page):

Marine Wire Size and Ampacity | West Marine

West Marine is committed to outfitting your life on the water. With over 250 store locations, 100,000 products in stock, and knowledgeable Associates, trust West Marine for your boating, sailing, fishing, or paddling needs. Shop with confidence - get free shipping to home or stores + price match...

www.westmarine.com

I personally push ~300A through 2/0 marine grade @12V for 15 minutes at a time. The wires get warm, but they are not hot.

 

[JK14]

Another thing that changes the ampacity ratings of wires is if they are running alone in free air or are in a conduit with other wires. The ratings in your tables match NEC tables for up to 3 wires in a conduit which gives 175A and 230A for 2/0 and 4/0 copper respectively with 75 degC rated insulation.
Sub-table 310.15(B)(2)(a) lists further ampacity reduction if more conductors are in the conduit, like 50% rating for 10-20 conductors.

The table 310.15(B)(17) for free air lists those same wires at 265A and 360A because the free air around the wire will allow better heat dissipation. Wiring from a battery to the inverter is commonly done in free air and so the Renogy table would be OK.

 

[DIYrich]

Note: free air may also be called "chassis" wiring limit.