Technical information

2. Special requirements

Besides all information presented and pointed out in the previous chapters for

industrial machinery, both NFPA 79 and UL508A (clause 65) set out more

restrictive specifications that must to be respected.

Particularly the main limitations can be summed up as follows:

•Use of some specific types of fuses

•Different feeder protection calculation

•Cable and wire: sizing and colours

•Different machine nameplate

•Obligation to calculate short circuit current

2.1 Fuses

A branch and feeder circuit fuse in industrial machinery is limited to Class RK1,

RK5, J,T or CC; class H, K, and G, fuses shall not be used.

2.2 Sizing of the feeder overcurrent protection

A feeder overcurrent protection device in the panel is expressly required only for

Industrial Machinery according to NFPA 79 (and section 66.7 of UL 508A), but its

presence is also required in NEC and CEC, where sizing rules are provided.

The rating/setting must be selected and sized basing on the addition of:

a) Rating/setting of the protection for the largest BCPC

b) 125% of all resistive loads

c) 125% of the large motor load

d) All other loads that can operate simultaneously

2.3 Cables

There are 2 main differences as regards cables; the first type is connected with

power conductors’ minimum sizing that can be used in panels while the second

deals with colours.

2.4 Minimum power cable section

Effective March,2007, 16 and 18 AWG power conductors will ONLY be allowed

under the Industrial Machinery section 66.5.4 with specific protection and will

NOT be allowed under the general panel provisions.

INDUSTRIAL MACHINERY