Cables Too Big?

PerryB67

Solar Enthusiast
I'm in the process of rewiring, installing a Class T fuse at the battery, a proper Blue Sea battery shutoff, and a 1500 watt inverter. The inverter recommends a 250a ANL fuse, but I'm installing a 250a class T fuse, and to use 2awg cables to the battery.

I mistakenly ordered and started installing 2/0 cables instead of 2 awg cables. I see nothing wrong with this, but I worked with Ethernet, TV cable, projectors, and sound in my school, not with huge wires (yes, I had a low-voltage electricians license), so what do I know. Aside from a slight price increase is there anything wrong with overwiring?

Thanks,

Perry
 

smoothJoey

SmooJo
I'm in the process of rewiring, installing a Class T fuse at the battery, a proper Blue Sea battery shutoff, and a 1500 watt inverter. The inverter recommends a 250a ANL fuse, but I'm installing a 250a class T fuse, and to use 2awg cables to the battery.

I mistakenly ordered and started installing 2/0 cables instead of 2 awg cables. I see nothing wrong with this, but I worked with Ethernet, TV cable, projectors, and sound in my school, not with huge wires (yes, I had a low-voltage electricians license), so what do I know. Aside from a slight price increase is there anything wrong with overwiring?

Thanks,

Perry
Nope, all things being equal bigger is better when it comes to wires, except for price.
You wires won't get hot and the voltage drop will be very low.
You will need lugs for 2/0 awg cable as well.
 

smoothJoey

SmooJo
I'm curious what inverter recommends a 250 amp fuse and 2 awg wire.
2 awg wire with 105C insulation is only good for 210 amps.
The insulation would likely melt off the wire before the fuse tripped.

Now for the math...
1500 ac watts / .85 conversion factor / 12 volts low cutoff = 147.058823529 service amps
147.058823529 service amps / .8 fuse headroom = 183.823529412 fault amps.

What is the round trip circuit length?
 

chrisski

Photon Sorcerer
I would hope a 250 amp Class T fuse holder is built for 2/0. I’ve had some problems with cheap 250 amp busbar s not fitting 2/0 lugs. Also with 2/0 wiring its a surprisingly harder to route than smaller wire. Just takes up so, so much pace.
 

rmaddy

Solar Addict
I would only use a 200A fuse max for 2AWG wire. But since you have 2/0 then you are fine with the 250A fuse.

The only possible issue you might have with 2/0AWG wire is if there is a terminal you need to insert the bare wire into and it isn't designed for 2/0AWG.

I am not that comfortable running 250 amps on just 2awg anyway. 2/0 is much better.
The OP would only be running 150A max which is fine with 2AWG. But you definitely don't want a 250A fuse with 2AWG.
 

PerryB67

Solar Enthusiast
Thanks for your opinions! I plan to finalize my cables to 2/0 for the remainder of the build. So far the only two cables I've purchased are the 6" cables between the battery bank >T250 fuse >Blue Sea switch on what I call the center board. Until I install an inverter the existing cabling is adequate and has worked without heating for the past three years.

I'm dyslexic and have problems reading the schematics others show here but here's the layout using Google Draw.
Schematic 21_10_14-page-001.jpg
I see no reason to include what goes after the WFCO and other wiring since it works fine and has nothing to do with the rewiring.

It's in a U-shape configuration with nothing further than 18", excepting the WFCO that is 30" from the Blue Sea switch/712 shunt.

A GoWise 1500 W continuous inverter will be installed. According to the GoWise installation manual it will need 2# pure copper wire, so I should be golden with 2/0.

I go back and forth between a 250a ANL fuse between the inverter and the Blue Sea switch and no fuse in that position. This is one spot I see conflicting recommendations, since a 250 T fuse is 6" from the battery. 260 ah SiO2 (lead crystal) batteries technically don't need a T fuse, but if I ever go to lithium it will already be there.
 
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