AC Power - two circuits better than one?

Circuits #1 and #3 are on one leg of the circuit breaker box and Circuits #2 and #4 are on the other leg of the circuit breaker box.
12-13-10: Puerto

Puerto,

Most if not all electrical panels made in, at least, the last 25 years have the odd number breaker space on the left hand side of the panel and the even numbers on the right hand side.

If that is the case for your panel then 1 & 2 are connected to Line 1 (leg). 3 & 4 are connected to Line 2.
You can verify at the receptacles with a volt meter. (See above post.)

Line 1 and line 2 alternate down each side of the panel.

Are you sure you have (4) dedicated branch circuits an not (4) separate circuits?

Dedicated branch circuits have their own hot, neutral, and equipment grounding conductor.

Where as for a single phase electrical panel found in most houses two separate branch circuits can share a neutral and equipment ground. In this case the two hot conductors must be install on opposite Lines, (legs).

Did you install the 4 circuits or did you hire an electrician? Were 4 dedicated branch circuits installed?

Example, four 12-2 W/ground Romex (NM-B) or two 12-3 W/grd Romex?

Jea48 Actually I have 4 separate circuits (not dedicated branch circuits as you described). I live in Mexico and had an electrician do the work. I would assume that circuits 1 & 3 would be on leg 1 because they are odd numbers while circuits 2 & 4 would be on leg 2. Here they use multi-strand wire, not romex so I had them pull three 12 gauge multi-strand wires from each respective breaker to the corresponding receptacle. The three lines were for hot/neutral/ground. The ground is grounded directly to the (USA) standard 200 amp panel which, in turn, is grounded to 8' of copper rod with #8 gauge wire.

I would assume that circuits 1 & 3 would be on leg 1 because they are odd numbers while circuits 2 & 4 would be on leg 2.
12-13-10: Puerto

Is the power that feeds your home 120/240Vac?
If yes do you have any equipment or appliances that use 240V? If yes check your panel you should see 2 pole breakers for the 240V equipment. (2 pole breaker takes two spaces.)

If that is the case then every other space down each side of the panel is the other Line, leg.

Line
L1 (1)......(2) L1
L2 (3)......(4) L2
L1 (5)......(6) L1
L2 (7)......(8) L2
ect.

Note: Twin breakers (slim) changes the ball game for the above example.
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What's the weather like?
COLD and snowy here in the Midwest!

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Jea48 Thanks, I don't want to get into the details but it's not possible - the outlet that's most convenient is part of a circuit that extends upstairs. In any event, it's not my house so reorganizing circuits on the breaker just isn't an option. I am going to load up the 20amp circuit as much as possible & divert the remainder to the cleanest 15amp circuit.