Wiring size opinions

[magicmantx]

I am installing the following components in building a new system using all Renogy components. I will have 12x 100 watt panels going to a 100a Renogy controller. 2- 200ah Renogy batteries. I will install a Renogy 3000watt inverter. Now here is my question on wiring sizes . If I go by the blue sea chart I would need 2/0 gauge wire from the inverter to the batteries but since the bigger draw I will have at one time will be a 13500 but ac for short periods of time , a 1500watt heater and a 7.0 cf refrigerator that draws 1.2 amps. so my max amp draw at any one time(I'd turn ac off to run microwave etc) would be under 30 amps. The AC will be connected in the breaker box with 12 gauge wire on a 20 amp circuit( spec by advent) . So all that said do I really need to spend the extra money to go with 2/0 wire to meet the maximum requirement of the inverter or go with 4 gauge which I have plenty of to do this project. What do ya'll think?

 

[Supervstech]

I am installing the following components in building a new system using all Renogy components. I will have 12x 100 watt panels going to a 100a Renogy controller. 2- 200ah Renogy batteries. I will install a Renogy 3000watt inverter. Now here is my question on wiring sizes . If I go by the blue sea chart I would need 2/0 gauge wire from the inverter to the batteries but since the bigger draw I will have at one time will be a 13500 but ac for short periods of time , a 1500watt heater and a 7.0 cf refrigerator that draws 1.2 amps. so my max amp draw at any one time(I'd turn ac off to run microwave etc) would be under 30 amps. The AC will be connected in the breaker box with 12 gauge wire on a 20 amp circuit( spec by advent) . So all that said do I really need to spend the extra money to go with 2/0 wire to meet the maximum requirement of the inverter or go with 4 gauge which I have plenty of to do this project. What do ya'll think?

4 gauge will handle around 70A

You have a 100A charge controller…

I am guessing you have a 12V inverter, so at 3000W, that will be 250A… now, if the inverter is capable of surge, it would pull double, or more…

You say your max draw would be around 30A… ac, 120V… so, 300+ amps at 12V… not counting inverter losses…

Bottom line… first, your inverter won’t output 30A… second… 4/0 is undersized for the max load of the inverter.

 

[magicmantx]

Actually the ac will pull 15a when running also have installed a soft start so no issue there. About the only other thing might be a 40" tv. I originally planned to run a 5k inverter but got a great deal on the 3k and it should do anything I plan on running. Yes 12v system, 3000watt running 6000w surge. panels wired 6s/2p . Also forgot to mention the cable runs will be very short total will probably be 5 ft the longest cable will be from the bus bar to the batteries . Inverter to fuse probably 6-8" fuse to bus bar another 6-8" bus to batteries about 2 ft. bus to controller will be about 18" . All lighting is LED and about the only thing I can think of that draws much power is a 900 watt microwave so 8.18 amps ac. I'll hook it up to my kilowatt meter to confirm that though. So If the ac is running at 15a and I run the microwave for a couple minutes I'd see 23 amps. We are pretty good at only running high draw things one at a time since our previous campers only had 400w system with 2/ 100ah Lith battery. The first system was done in 2016 and was 400 w and ran the typical 4 6v deep cycle trojan batteries so we learned to conserve power when dry camping. If we need to run the ac for extended periods we'll run it off the generator but want to be able to run it like at rest stop to eat lunch etc . I haven't completely decided which way to go but am starting to believe there are certain limits in my system that going with 4 gauge will be plenty.

 

[ksmithaz1]

4 gauge will handle around 70A

You have a 100A charge controller…

I am guessing you have a 12V inverter, so at 3000W, that will be 250A… now, if the inverter is capable of surge, it would pull double, or more…

You say your max draw would be around 30A… ac, 120V… so, 300+ amps at 12V… not counting inverter losses…

Bottom line… first, your inverter won’t output 30A… second… 4/0 is undersized for the max load of the inverter.

Well 2/0 is 350 in free air, 175ish in conduit. 4/0 is 230ish in conduit, like 450 in free air. I doubt the battery will discharge at that rate. Put a 175A fuse/breaker on it if it's 2/0. Put a 300A fuse/breaker on it for 4/0. Conductors are not rated on surge, they are rated on continuous draw. A 30A breaker will handle 60A for about a second, maybe a little longer. Motor surge shouldn't last more than 500ms.

 

[ksmithaz1]

Actually the ac will pull 15a when running also have installed a soft start so no issue there. About the only other thing might be a 40" tv. I originally planned to run a 5k inverter but got a great deal on the 3k and it should do anything I plan on running. Yes 12v system, 3000watt running 6000w surge. panels wired 6s/2p . Also forgot to mention the cable runs will be very short total will probably be 5 ft the longest cable will be from the bus bar to the batteries . Inverter to fuse probably 6-8" fuse to bus bar another 6-8" bus to batteries about 2 ft. bus to controller will be about 18" . All lighting is LED and about the only thing I can think of that draws much power is a 900 watt microwave so 8.18 amps ac. I'll hook it up to my kilowatt meter to confirm that though. So If the ac is running at 15a and I run the microwave for a couple minutes I'd see 23 amps. We are pretty good at only running high draw things one at a time since our previous campers only had 400w system with 2/ 100ah Lith battery. The first system was done in 2016 and was 400 w and ran the typical 4 6v deep cycle trojan batteries so we learned to conserve power when dry camping. If we need to run the ac for extended periods we'll run it off the generator but want to be able to run it like at rest stop to eat lunch etc . I haven't completely decided which way to go but am starting to believe there are certain limits in my system that going with 4 gauge will be plenty.

#4 is 150A free-air. I'd likely put an 100A breaker on it, but that's only 1200W. I'd go with 2/0 and a 250A fuse. That get's you to 3KW, and if your runs are short and not in conduit you should be fine.

 

[Supervstech]

Actually the ac will pull 15a when running also have installed a soft start so no issue there. About the only other thing might be a 40" tv. I originally planned to run a 5k inverter but got a great deal on the 3k and it should do anything I plan on running. Yes 12v system, 3000watt running 6000w surge. panels wired 6s/2p . Also forgot to mention the cable runs will be very short total will probably be 5 ft the longest cable will be from the bus bar to the batteries . Inverter to fuse probably 6-8" fuse to bus bar another 6-8" bus to batteries about 2 ft. bus to controller will be about 18" . All lighting is LED and about the only thing I can think of that draws much power is a 900 watt microwave so 8.18 amps ac. I'll hook it up to my kilowatt meter to confirm that though. So If the ac is running at 15a and I run the microwave for a couple minutes I'd see 23 amps. We are pretty good at only running high draw things one at a time since our previous campers only had 400w system with 2/ 100ah Lith battery. The first system was done in 2016 and was 400 w and ran the typical 4 6v deep cycle trojan batteries so we learned to conserve power when dry camping. If we need to run the ac for extended periods we'll run it off the generator but want to be able to run it like at rest stop to eat lunch etc . I haven't completely decided which way to go but am starting to believe there are certain limits in my system that going with 4 gauge will be plenty.

15A at 120V, add in inverter losses, and you have 2160W… divide by 12V, and you get 180A… so… #4 will catch fire…

 

[magicmantx]

Looks Like I'll be going with the 2/0. Sometimes you know the answer before you ask lol. Just need to smack it with some$$$$ lol. Thanks for the help.