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Reading a panel schedule: which breaker, which leg, which wire

A panel schedule lists every breaker space by number, odd numbers down the left and even down the right, with each row alternating between the two hot legs; a two-pole 240 V breaker takes two spaces on the same side, one above the other, and so lands on both legs.

Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.

What it is for

You are sent to kill the circuit for the upstairs bathroom and the schedule says 14. You need to trust the schedule, know that 14 is on the right side, and know that if the label is wrong the meter is the last word. Adding a circuit later means finding a free space, keeping the legs balanced and writing down what you did for the next person.

How to think about it

Read the spaces as a grid: 1 and 2 across the top, 3 and 4 below, and so on. Row one is leg A, row two is leg B, row three leg A again. A two-pole breaker straddles two rows on one side, so it sees both legs and gets 240 V. Add up the amps on each leg from the schedule and keep them within a few amps of each other. Before pulling a cover: main off if you can, lock, verify the bus dead.

Worked example

Space 7: left side, row 4, leg B
Odd numbers left. Row 4 is an even row, so leg B.
Space 12: right side, row 6, leg B
Even numbers right. Row 6, leg B as well; 7 and 12 are on the same leg despite being on opposite sides.
Two-pole breaker in spaces 9 and 11: rows 5 and 6, legs A and B, 240 V
One side, two rows, both legs.
Leg A totals 46 A, leg B totals 34 A: move a 6 A circuit from A to B
40 A and 40 A. Balanced legs mean less on the neutral and a cooler panel.

Your turn

Write which leg space 3 is on.

space 3: row 2, leg

The trap

Believing the schedule over the meter. Schedules are written by the last person, in pencil, before the remodel. Turn the breaker off and test the outlet dead before anyone touches a wire.

Practise reading a panel schedule on HoneA question on it now, a coding challenge where there is one, and it is remembered for review. Free, no email needed.