Thermal-Magnetic Circuit Protectors

These maximum current values assume the use of insulated copper conductors with 75oC temperature rating, and are calculated based on NEC Article 310, Table 310-16. In most cases this value is the maximum ampacity of that wire or combination of wires (as listed in the above table) which has the greatest current carrying capacity. The actual allowable current for a particular application depends on the number, size, insulation class, and other characteristics of the wires used.

b	Replacement adapter is 9080GH64, $1.10 each, standard pack of 10.

c	Discount schedule CP5.

Selection

To properly select a Class 9080 Type GCB circuit protector, follow these steps:

1.	Determine the inrush correction factor from Table 24.29.

2.	Determine the temperature correction factor from Table 24.30.

3.	Determine the sealed current of the load that is being protected.

4.	Multiply the sealed current by the two correction factors and choose the closest circuit protector.

Choosing a circuit protector with a value lower than the calculated value might cause nuisance tripping, while choosing the larger might provide a protector that will not properly protect the load.

Table 24.29:

Table A—Inrush Ratio Correction Table

Note: For resistive loads, use inrush correction factor of 1.0.

Table 24.30:

Table B—Ambient Temperature Correction Table

Ambient
Temperature

70oF

100oF

120oF

140oF

160oF

180oF

200oF

(21.1oC)

(37.8oC)

(48.9oC)

(60oC)

(71.1oC)

(82.2oC)

(93.3oC)

File
CCN

E152841
QVNU2

Example: Solenoid with sealed current of 0.75 A, an inrush ratio of 1:6, and in an ambient temperature of 85oF: 0.75 x 1.5 x 1.05 = 1.18 Choose the 1.2 A protector

Tripping Time: Tripping time of the circuit protector is determined from Table 24.31. Divide the circuit protector value by the temperature correction factor from Table 24.30 to determine actual rated current referenced in Table 24.31.

Table 24.31:

Table C—Tripping Times in Seconds at 70oF (21.1oC)

Percent rated
current

2000% and
greater