inverter fuse/breaker

[starcraft69]

I am purchasing a 3000 watt inverter and wondering should i use a ANL 300amp fuse or a 300amp breaker between batteries and inverter?

[RJsfishin]

I thought this was a "fuse size" thread,.....turned into a "wire size" thread, amazing

My OEM main house battery cables are 8ft long...no fuse / breaker anywhere
My OEM generator battery cables are 6 ft long... no fuse / breaker anywhere

Moral of the story, learn to install stuff correctly, and you don't need any fuse / breaker on battery cables. Its always been that way.

[2oldman]

MEXICOWANDERER wrote:
Sometime for fun, load a 3,000 watt inverter for a half-minute. When the timer stops run outside and touch the fasteners and terminals on the inverter.

Exactly. That's why higher voltage is better. Run it longer and the batteries will start to heat up.

[MrWizard]

:R

on this forum it is colon followed by capital R no spaces

[GordonThree]

pianotuna wrote:
My Christmas Gift to you GordonThree:

GordonThree wrote:
What's the rolls eyes picture shortcut?

Thanks Don! 🙂

[pianotuna]

My Christmas Gift to you GordonThree:

GordonThree wrote:
What's the rolls eyes picture shortcut?

[MEXICOWANDERER]

Examine the copper contact area of a 4/0 cable. The correct fastener size for 4/0 cable is 1/2". Half inch diameter studs and nuts with 3/4" flats.

Sometime for fun, load a 3,000 watt inverter for a half-minute. When the timer stops run outside and touch the fasteners and terminals on the inverter.

Fun Huh?

[GordonThree]

What's the rolls eyes picture shortcut?

[BFL13]

I got a 3000w inverter because it was on sale for less than the 2000w one I actually needed to run the MW. I wired the 3000 for running the MW at expected amps draw (under 150 amps) with parallel #4s three ft long (you get the four 3ft #4s with the 3000w inverter, so "they" must think that is ok)

Only other thing is to wire fat enough to prevent voltage hitting inverter alarm when batts are down to 50% and you still want to make toast with the electric toaster (90 amps)

Fattest wire I have ever used is #1 AWG 6ft long, store bought with lug terminals on. Good enough for me. YMMV.

[MrWizard]

i am very big on safety
BUT .. sometimes comments are overboard
if you want to run the whole house full time from the inverter from batteries and solar off grid with a huge battery bank meaning MW while running the A/C and the Dw's hair dryer
then yeah use 4/0

a couple of minutes of MW while making coffee, does not need that
it does not hurt to go big
but it is not the necessity some people seem to think

not when the loads are not high enough and consistent enough to make that needed

most of the users on here buying 3kw inverter will never need/use 3kw of power

[GordonThree]

2oldman wrote:

starcraft69 wrote:
Is 300amp breaker the right size?

You may want to consider upping the input voltage to 24 or higher on a big inverter. No wrestling with cables as big as your thumb.

x2 on this ... sounds like OP already bought the hardware though

[2oldman]

starcraft69 wrote:
Is 300amp breaker the right size?

You may want to consider upping the input voltage to 24 or higher on a big inverter. No wrestling with cables as big as your thumb.

[KD4UPL]

1/0 isn't big enough for a 3 kW inverter. I would think you would want 4/0 if you're going any distance at all. A 3,000 watt inverter at 12 volts will be drawing 250 amps without taking efficiency into consideration. Figure it's only 80% efficient and now you're drawing 312 amps. If the voltage sags below 12 volts, which it likely will, you would be drawing even more current. 3/0 is rated for 350 amps in free air (less if in conduit). IF you're really going to draw 3 kW from the inverter I would use 4/0 cable and a 400A breaker or class T fuse. The breaker that TechWriter liked to is rated for a 5,000 A interrupt ratting at 48v. It doesn't say what it would be at 12v but likely substantially higher. The only way to find out what your battery bank's fault current is would be to find out from the manufacturer.
Carling Technologies makes lots of high current breakers resold by many of the inverter manufactuerers. Their F series is rated for up to 50,000 Amps of fault current up to 125v DC.
As difficult and expensive as a suitable 400A breaker may be to find I would probably just use a fuse unless you will never be using your inverter at it's full capacity.

[MrWizard]

AC continuous duty would be 150amps
but this is long wire runs, possibly in metal conduit
for short inverter runs i think it should be OK

i have 2ft runs of #2 fused with a 200amp breaker, but load seldom exceeds 90amps
this is on a 2KW continuous 3KW surge inverter

i've got some bigger wire someplace to replace it, but i sized it to the expected load, not max capability, it can run the coffee maker or MW without overheating the wire

[Acampingwewillg]

I just reran all my compartment battery cables after getting a new 250 amp alternator and replacing batteries(6-6 volt) and since doing it myself, I used 4/0 for everything including replacing a 300 amp T fuse. There not cheap so if there is an option to use a resettable device, I'd go for it.