Grouping Derating NFC

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Tableau 52N

Installation Above Ground Grouping on a Single Layer Derating Factor Reference Method
Number of Grouped Cables
1 2 3 4 5 6 7 8 9 12 16 20
Bunched in air, on a surface, embedded or enclosed 1.00 0.80 0.70 0.65 0.60 0.55 0.55 0.50 0.50 0.45 0.40 0.40 B, C
Single layer on wall, floor or unperforated cable tray systems 1.00 0.85 0.79 0.75 0.73 0.72 0.72 0.71 0.70 0.70 0.70 0.70 C
Single layer fixed directly under a wooden ceiling 1.00 0.85 0.76 0.72 0.69 0.67 0.66 0.65 0.64 0.64 0.64 0.64 C
Single layer on a perforated horizontal or vertical cable tray systems 1.0 0.88 0.82 0.77 0.75 0.73 0.73 0.72 0.72 0.72 0.72 0.72 E, F
Single layer on cable ladder systems or cleats etc. 1.0 0.88 0.82 0.80 0.80 0.79 0.79 0.78 0.78 0.78 0.78 0.78 E, F

Tableau 52O

Number of layers 2 3 4 or 5 6 to 8 9 and more
Derating factor 0.80 0.73 0.70 0.68 0.66

Tableau 52P

Number of cables vertically installed Number of cables horizontally installed
1 2 3 4 5 6
1 1.00 0.94 0.91 0.88 0.87 0.86
2 0.92 0.87 0.84 0.81 0.80 0.79
3 0.85 0.81 0.78 0.76 0.75 0.74
4 0.82 0.78 0.74 0.73 0.72 0.72
5 0.80 0.76 0.72 0.71 0.70 0.70
6 0.79 0.75 0.71 0.70 0.69 0.68

Tableau 52Q

Number of cables vertically installed Number of cables horizontally installed
1 2 3 4 5 6
1 1.00 0.87 0.77 0.72 0.68 0.65
2 0.87 0.71 0.62 0.57 0.53 0.50
3 0.77 0.62 0.53 0.48 0.45 0.42
4 0.72 0.57 0.48 0.44 0.40 0.38
5 0.68 0.53 0.45 0.40 0.37 0.35
6 0.65 0.50 0.42 0.38 0.35 0.32

Tableau 52R

Number of cables or circuits Distance between multi-core cables or circuits of single-core cables
Cable to Cable Clearance
Touching One OD (1) 0.25 m 0.50 m 1.00 m
2 0.76 0.79 0.84 0.88 0.92
3 0.64 0.67 0.74 0.79 0.85
4 0.57 0.61 0.69 0.75 0.82
5 0.52 0.56 0.65 0.71 0.80
6 0.49 0.53 0.60 0.69 0.78

Note (1): A clearance of one cable overall diameter

Tableau 52S

Number of ducts Distance between ducts
Touching 0.25 m 0.50 m 1.00 m
2 0.87 0.93 0.95 0.97
3 0.77 0.87 0.91 0.95
4 0.72 0.84 0.89 0.94
5 0.68 0.81 0.87 0.93
6 0.65 0.79 0.86 0.93

Tableau 52T

Derating factor
Number of circuits or multi-core cables
1 2 3 4 5 6 7 8 9 12 16 20
1.00 0.71 0.58 0.5 0.45 0.41 0.38 0.35 0.33 0.29 0.25 0.22

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