Critical questions about workshop wiring
Find your amp needs guidelines
To determine how much capacity your shop needs, first find your highest amp-draw tool (often a tablesaw or dust collector), and multiply the amperage by 125 percent
Highest amps x 1.25 = (A) _______
Now, total the amperage of the highest draw tools that run simultaneously, such as a tablesaw and dust collector, router and shop vac, etc.
Simultaneous tool amps = (B) _______
Total the amp draw of all other loads that run continuously, such as lighting, heat/air conditioning, air filter, radio, etc. (If amps unknown, such as with lights, divide watts by voltage to get amps.)
Continuous-draw amps = (C) _______
MINIMUM AMPS REQUIRED FOR SHOP (A+B+C) = _______
Highest draw (A):
(18-amp tablesaw) × 1.25 = 22.5
Highest simultaneous (B):
(18-amp saw+11-amp dust coll.) = 29
(lights, heat, television, air filter) = 24
Minimum Amps Required (A+B+C) = 75.5
Powering this shop adequately requires 80-amps of extra capacity in the existing service panel, or an 80-amp subpanel.
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