630-Electric Welders

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I. General

considers both the magnitude and the duration of the load while the welder is in use.

630.12 Overcurrent Protection. Overcurrent protection for arc welders shall be as provided in 630.12(A) and (B).Where the values as determined by this section do not correspond to the standard ampere ratings provided

630.1 Scope. This article covers apparatus for electric arc welding, resistance welding, plasma cutting, and other similar welding and cutting process equipment that is connected to an electrical supply system.

II. Arc Welders

630.11 Ampacity of Supply Conductors. The ampacity of conductors for arc welders shall be in accordance with 630.11(A) and (B).

(A) Individual Welders. The ampacity of the supply con- ductors shall be not less than the / leff value on the rating plate. Alternatively, if the 7, eff is not given, the ampacity of the supply conductors shall not be less than the current value determined by multiplying the rated primary current in amperes given on the welder rating plate by the factor shown in Table 630.11 (A) based on the duty cycle of the welder.

Table 630.11(A) Duty Cycle Multiplication Factors for Arc

Welders

Multiplier for Arc Welders

Nonmotor Motor

Duty Cycle Generator Generator

100 1.00 1.00

90 0.95 0.96

80 0.89 0.91

70 0.84 0.86

60 0.78 0.81

50 0.71 0.75

40 0.63 0.69

30 0.55 0.62

20 or less 0.45 0.55

(B) Group of Welders. Minimum conductor ampacity shall be based on the individual currents determined in

630.11(A) as the sum of 100 percent of the two largest welders, plus 85 percent of the third largest welder, plus 70 percent of the fourth largest welder, plus 60 percent of all remaining welders.

Exception: Percentage values lower than those given in

630.11(B) shall be permitted in cases where the work is

such that a high-operating duty cycle for individual

welders is impossible.

FPN: Duty cycle considers welder loading based on the use to be made of each welder and the number of welders supplied by the conductors that will be in use at the same time. The load value used for each welder
in 240.6 or where the rating or setting specified results in unnecessary opening of the overcurrent device, the next higher standard rating or setting shall be permitted.
(A) For Welders. Each welder shall have overcurrent pro tection rated or set at not more than 200 percent of 7 lmax. Alternatively, if the /, max is not given, the overcurrent pro tection shall be rated or set at not more than 200 percent of the rated primary current of the welder.
An overcurrent device shall not be required for a welder that has supply conductors protected by an overcurrent device rated or set at not more than 200 percent of / lmax or at the rated primary current of the welder.
If the supply conductors for a welder are protected by an overcurrent device rated or set at not more than
200 percent of 7, max or at the rated primary current of the welder, a separate overcurrent device shall not be required.

(B)