FFieldDeskElectrical and HVAC

Table 310.16 · screening

Read the Table 310.16 ampere column.

Pick the temperature column. Most breakers and lugs are 60°C or 75°C, so the circuit is usually limited to those. 90°C is the insulation rating.

Input values to calculate

Calculated results

SizeAmperes at 75°C
1420 A
1225 A
1035 A
850 A
665 A
485 A
3100 A
2115 A
1130 A
1/0150 A
2/0175 A
3/0200 A
4/0230 A
250255 A
300285 A
350310 A
400335 A
500380 A
600420 A
750475 A
1000545 A
Report calculation

What this sheet does

  1. This page does not size a job. It shows how many amperes each wire can carry.
  2. Pick copper or aluminum, then 60°C, 75°C, or 90°C.
  3. Each row is a wire size and the amperes for the temperature you picked.
  4. On a normal circuit, 14 AWG copper stops at 15 A, 12 AWG at 20 A, and 10 AWG at 30 A. A motor circuit is one case where the breaker can be higher than that.