96 APPENDIX
bepmarine.com
Wire & Cable Technical Data
3% Voltage Drop at 12 Volts
Conductors Sized (AWG) for 3% Voltage Drop Use 3% voltage drop for any “critical application” affecting the safety of the vessel or its passengers: bilge pumps, navigation lights, electronics, etc.... Important! Length (feet): Determined by measuring the length of the conductor from the positive (+) power source connection to the electrical device and back to the negative (-) power source connection. Note that the power source connection may be either the battery, panelboard or switchboard. Current (amps): Determined by adding the total amps on a circuit. Conductor sizes not covered in Table B or Table C may be calculated by using the following formula: CM = K x I x L E After calculating the Circular Mil Area (CM), use Table E to determine the proper conductor size (National Fire Protection Agency and Coast Guard require that the next larger conductor be used when the calculated CM area falls between the two conductor sizes). CM = Circular Mil Area of Conductors K = 10.75 (Constant representing the mil-foot resistance of copper) I = Current - amps / L = Length - feet E = Voltage drop at load (in voltage drop in a decimal expression) For Example... Q: A bilge pump draws 10 amps. The positive run is 11 feet from the power panel, including the float switch. The negative run is only 10 feet. What size is the wire?
Current (Amps)
Length
5 10 15 20 25 30 40 50 60 70 80 90 100
10' 3m18141210108 6 6 6 6 6 4 4 15' 5m161210108 8 6 6 4 4 4 2 2 20' 6m1410108666442222 25' 8m121086664422211 30' 9m121086444222211 40' 12m10 8 6 6 4 4 2 2 1 1/01/02/02/0 50' 15m10 6 6 4 4 2 2 1 1/0 2/0 3/0 4/0 4/0 60' 18 m 10 6 6 4 2 2 1 1/0 2/0 3/0 3/0 4/0 4/0 70' 21 m 8 6 4 2 2 1 1/0 2/0 3/0 3/0 4/0 4/0 80' 24m 8 6 4 2 2 1 1/0 2/0 3/0 4/0 4/0 90' 27 m 8 4 2 2 1 1/0 2/0 3/0 4/0 4/0 100' 30m 6 4 2 2 1 1/0 2/0 3/0 4/0 110' 33m 6 4 2 2 1 1/0 2/0 3/0 4/0
120' 36 m 6 4 2 1 1/0 2/0 3/0 4/0 130' 40 m 6 2 2 1 1/0 2/0 3/0 4/0 140' 43 m 6 2 2 1/0 2/0 3/0 4/0 150' 46 m 6 2 1 1/0 2/0 3/0 4/0 160' 49 m 6 2 1 1/0 2/0 3/0 4/0 170' 52 m 6 2 1 2/0 3/0 3/0 4/0
3% Voltage Drop at 24 Volts
Current (Amps)
Length
5 10 15 20 25 30 40 50 60 70 80 90 100
10' 3m1818161412121010108 8 8 6 15' 5m181614121210108 8 6 6 6 6 20' 6m1814121010108 6 6 6 6 4 4 25' 8m16121210108 6 6 6 4 4 4 4 30' 9m161210108 8 6 6 4 4 4 2 2 40' 12m1410108666442222 50' 15m121086664422211 60' 18m12108 6 6 4 4 2 2 1 1 1/01/0 70' 21m12 8 6 6 4 4 2 2 1 1 1/01/02/0 80' 24m10 8 6 6 4 4 2 2 1 1/01/02/02/0 90' 27m10 8 6 4 4 2 2 1 1/0 1/0 2/0 2/0 3/0 100' 30m10 6 6 4 4 2 2 1 1/0 2/0 2/0 3/0 3/0 110' 33 m 10 6 6 4 2 2 1 1/0 1/0 2/0 3/0 3/0 4/0 120' 36 m 10 6 4 4 2 2 1 1/0 2/0 3/0 3/0 4/0 4/0 130' 40m 8 6 4 2 2 2 1 1/0 2/0 3/0 3/0 4/0 4/0 140' 43 m 8 6 4 2 2 1 1/0 2/0 3/0 3/0 4/0 4/0 150' 46 m 8 6 4 2 2 1 1/0 2/0 3/0 3/0 4/0 4/0 160' 49 m 8 6 4 2 2 1 1/0 2/0 3/0 4/0 4/0 4/0 170' 52m 8 6 2 2 1 1 2/0 3/0 3/0 4/0 4/0 3% Voltage Drop at 32 Volts Current (Amps) Length 5 10 15 20 25 30 40 50 60 70 80 90 100 10' 3m18181616141412121010108 8 15' 5m18161414121210108 8 8 6 6 20' 6m181612121210108 8 6 6 6 6 25' 8m1814121210108 8 6 6 6 6 4 30' 9m16141010108 8 6 6 6 4 4 4 40' 12m161210108 8 6 6 4 4 4 2 2 50' 15m141288866442222 60' 18m141088664422221 70' 21m121066664222110 80' 24m121066644221100 90' 27m12 8 6 6 6 4 2 2 2 1 1/01/02/0 100' 30m12 8 6 6 4 4 2 2 1 1/01/02/02/0 110' 33m10 8 6 6 4 4 2 2 1 1/01/02/02/0 120' 36m10 8 6 4 4 2 2 1 1/0 1/0 2/0 2/0 3/0 130' 40m10 8 6 4 4 2 2 1 1/0 2/0 2/0 3/0 3/0 140' 43 m 10 6 6 4 2 2 1 1/0 1/0 2/0 3/0 3/0 3/0 150' 46 m 10 6 6 4 2 1 1 1/0 2/0 2/0 3/0 3/0 4/0 160' 49 m 10 6 4 4 2 1 1 1/0 2/0 3/0 3/0 4/0 4/0 170' 52m 8 6 4 2 2 1 1 1/0 2/0 3/0 3/0 4/0 4/0
A: Use the formula to reach the correct answer:
Table D shows that 12 AWG wire has a CM area of 6,500 and is the correct choice. However, SAE wire has a CM area of only 5,833. Under NFPA and USCG regulations, 10 SAE wire must be used.
Powered by FlippingBook