Technical information

The same calculation for the minimum capacity is also applied for the conductor

inside the panel: the uprated cross-section is AWG 12 (25 A).

The resistive load command requires the use of a contactor sized in current. Solid

state contactors are particularly suitable for this application: for example, use can

be made of the 156-C20xA3, three-phase with rated current of 20A and

maximum voltage of 600V.

1.10 Lighting branch circuit

100L 500L

These are power circuits for lamps used in the working process, both for lighting

( “standard-duty” lamps) and for other purposes (for example infrared lights for

drying; “heavy-duty” lamps). These are not the panel's maintenance lights.

Also for this type of circuit UL508A gives an overview of the main regulations and

distinguishes between:

• Standard-duty lamps (incandescent or fluorescent): the BCP must be calibrated

at not more than 20 A; conductors must have a capacity above the

size/calibration of the protection;

• Heavy-duty lamps (incandescent or infrared): il BCP must be calibrated at not

more than 50 A; the conductors must have a capacity above the size/ calibration

of the protection;

There are no limits on the power supply voltage.

Some differences are to be considered between the various norms as far as simply

the lighting circuits are concerned:

a) the NFPA 79 standard for Industrial Machinery imposes a BCP with a size no

greater than 15 A and a maximum supply voltage of 150 V; one side of the

circuit must be grounded.

BRANCH CIRCUIT