Electrical Load Calculation

So, i'm running a 240V 65amp feeder cable(four copper wires: two 6 gauge hot wires, one 6 gauge neutral, and one 8 gauge ground) from my main panel out to the sub panel in my grow room.

Here's what i'm planning to have on my sub-panel:

30amp breaker for 240v circuit
20amp breaker for 120v circuit
20amp breaker for 120v circuit

How many more 120V circuits could i put on this panel, if any?

PumpedUpKicks said:

So, i'm running a 240V 65amp feeder cable(four copper wires: two 6 gauge hot wires, one 6 gauge neutral, and one 8 gauge ground) from my main panel out to the sub panel in my grow room.

Here's what i'm planning to have on my sub-panel:

30amp breaker for 240v circuit
20amp breaker for 120v circuit
20amp breaker for 120v circuit

How many more 120V circuits could i put on this panel, if any?

Click to expand...

what the devil are you running, 20 amps can actually run a small house lol, but you look at the amp rating of all your special equip add it up and every 20 amps or so that's left over you can add about 5 general purpose circuits.

thunderbay said:

what the devil are you running, 20 amps can actually run a small house lol, but you look at the amp rating of all your special equip add it up and every 20 amps or so that's left over you can add about 5 general purpose circuits.

Click to expand...

Nvm, i figured out how to calculate it. For anyone interested, here's the breakdown:

- i have a 4 wire feeder cable (2 hot, 1 neutral, 1 ground) powering a sub panel which is 65amps @ 240v
- both of the hot wires = 65amps @ 120v
- If i install a 240v circuit that draws 30amps, it draws from 30 amps @ 120v from both hot wires.
- You now have 35 amps @ 120v capacity left on both hot wires
- If i now add an additional circuit that's 20amps @ 120v, it only draws from ONE of the hot wires.
- I'm left with 35 amps @ 120v capacity on one of the hot wires and 15 amps @ 120v on the other.

In this example, i'm assuming the breakers are used at full capacity, which almost always they are not. I hope this is helpful to someone else...