# Minimum current ampacity (mca) calculation, Maximum overcurrent protection (mop) calculation, Finding the actual mop value – Mammoth 800 to 5500 CFM: Dedicated Outdoor Air System with Enthalpy Wheels (VHC) User Manual

## Page 26: Important

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MAMM-VHC-IOM-1A (JANUARY 2013)

26

Minimum Current Ampacity (MCA)

Calculation

1.25 x FLA of larger hp motor or compressor = _____

1.25 x heater FLA

= + _____

Sum of all other motors FLA

= + _____

Wheel drive motor and standard controls FLA = + _____

Calculated total MCA

= _____

Maximum Overcurrent Protection (MOP)

Calculation

2.25 x FLA of larger hp motor or compressor = _____

Electric heater FLA

= + _____

Sum of all other motors FLA

= + _____

Wheel drive motor and standard controls FLA = + _____

Calculated total MCA

= _____

Actual MOP (from Table E5)

= _____

Finding the Actual MOP Value

From the calculated MOP value, select the next smallest

value of protection from the Standard Overcurrent Protec-

tion chart below to get the actual MOP value (maximum

value of overcurrent device).

IMPORTANT

If this method leads to an actual MOP value being smaller

than the calculated total MCA, then a larger value must

rather be selected, such that the actual MOP is at least

equal to the calculated total MCA.

Table E4:

For Dual Circuit On/off Units
6 tons

Two 3 ton on/off compressors

8 tons

Two 4 ton on/off compressors

10 tons

Two 5 ton on/off compressors

12 tons

Two 6 ton on/off compressors

14 tons

Two 7 ton on/off compressors

16 tons

Two 8 ton on/off compressors

21 tons

Two 10 ton on/off compressors

For Dual Circuit VRC

®

Units

6 tons

One 3 ton on/off compressor

One 3 ton VRC compressor

8 tons

One 4 ton on/off compressor

One 4 ton VRC compressor

10 tons

One 5 ton on/off compressor

One 5 ton VRC compressor

12 tons

One 6 ton on/off compressor

One 6 ton VRC compressor

14 tons

One 7 ton on/off compressor

One 7 ton VRC compressor

16 tons

One 8 ton on/off compressor

One 8 ton VRC compressor

21 tons

One 10 ton on/off compressor

One 10 ton VRC compressor

Table E5: Standard Overcurrent Protection

3

40

250

4

45

300

5

50

350

6

60

400

7

70

450

8

80

500

9

90

600

10

100

650

12

110

700

15

125

750

20

150

800

25

175

850

30

200

900

35

225

1,000

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