Watts across multiple voltages

[Skippyp]

I want to make sure I'm sizing wires and breakers/fuses correctly...
If I can pull 3000w at 110vac from my inverter, then my appliance is using 27.3amps (3000/110 ignoring losses).
If that same inverter load is powered from a 24v DC battery, then I'm using 125amps (3000/24).
Fusing the positive lead from that battery would need to be ~125% or about 150a (if I can surge to 6000w then 6000/24*1.25 or a huge 312.5a breaker! In that case, since I will use 00 wire, size for wire and not load.

If I follow the watts, then I should be okay. Right? Seems counterintuitive that the same 3000w requires much smaller wire on AC than DC but it's the amps, I guess.

 

[snoobler]

I want to make sure I'm sizing wires and breakers/fuses correctly...
(1) If I can pull 3000w at 110vac from my inverter, then my appliance is using 27.3amps (3000/110 ignoring losses).
(2) If that same inverter load is powered from a 24v DC battery, then I'm using 125amps (3000/24).
(3) Fusing the positive lead from that battery would need to be ~125% or about 150a (if I can surge to 6000w then 6000/24*1.25 or a huge 312.5a breaker! In that case, since I will use 00 wire, size for wire and not load.

If I follow the watts, then I should be okay. Right? Seems counterintuitive that the same 3000w requires much smaller wire on AC than DC but it's the amps, I guess.

1) Correct
2) Correct
3) Correct, but surges are often omitted unless surges are likely and of long duration. Most high frequency inverters can't accept a meaningful surge for longer than 1/2 a second if that.

No. You should follow current, but power is useful in determining current for a given voltage.

Another consideration is the voltage drop, which correlates directly with power loss:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

Enter gauge, voltage, distance and current.

Step 1) Determine if your wire is rated for the current.
Step 2) Determine if the gauge, voltage, distance and current yield an acceptable voltage drop.

 

[Skippyp]

Thanks @snoobler. This will be a portable system similar to one Will and others have built, so wire runs are short. Therefore I intend to oversize the wires since the cost will be manageable.
I'm hoping that between 1kw ish of solar and 2.8kw from my Honda eu3000is I will be able to keep this 24v 272ah bank going strong if another Ike hits home.
Just wish the budget afforded 48v, but I gotta start somewhere.