General & Planning · CEC Section 6 & 12

Panel Fill Calculator

Calculate total breaker spaces used, available remaining slots, tandem breaker rules, and whether adding a sub-panel is required for your expansion.

1. Panel Configuration

Panel Maximum Space Rating (Slots)

Single-Pole Breakers (120V)

Double-Pole Breakers (240V, takes 2 slots)

Tandem / Slim Breakers (2 circuits in 1 slot)

2. Panel Capacity Status

CEC Breaker Slot Rule

PHYSICAL SLOTS USED

0 / 32

REMAINING OPEN SLOTS

0 Slots

PANEL CAPACITY UTILIZATION

Capacity OK: Your panel has open slots for expansion.

Key Rules for Panel Spaces

Double-pole 240V breakers (dryer, range, AC, EV charger) occupy 2 physical full-width slots.
Tandem (twin/slim) breakers fit 2 separate circuits into 1 physical slot, provided the panel label explicitly allows tandem breakers in those specific slots.
If your panel is at 100% capacity, installing a sub-panel (e.g. 60A or 100A feed) is the cleanest way to add new circuits without violating CEC listing restrictions.

Panel spaces

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