The maximum voltage drop in feeder is 3 % the voltmeter reading = 240 – 0.03 * 240 = 240 – 7.2 = 232.8 volts
The conductor ampacity of 1/0 THWN in dry location ( 900C) = 170 amperes ( NEC Table 310.15(B)(16)) Ambient temperature correction factor at 1080F = 0.91 ( NEC Table 310.15(B)(2)) Raceway conductor bundle adjustment factor for 4 conductors = 0.8 ( NEC Table 310.15(B)(3)(a)) corrected ampacity = 170 * 0.8*0.91 = 124 amperes
First 3000 VA the demand factor is 100% = 3000 * 100 % = 3000 VA remaining (4000-3000) = 1000 ( demand factor = 35%) = 1000 * 0.35 = 350 VA total demand load = 3000 + 350 = 3350 VA
For 5 conductors in flexible cord allowed ampacity percentage = 80 % of rated amapcity Allowed amapcity of each conductor with 150 Ampere rating = 150 * 0.8 = 120 amperes.
NEC Table 250.102(C)(1) For over 3/0 AWG and 350 kcmil the required bonding jumper size is 2 AWG
Protection rating for an electric water heater should be less than 150% of the rating of device. Protection size = 4200 / 240 * 1.5 Protections size = 26.25 A The nearest next size over current device is 30 A.
Conductor ampacity = 125% of FLC = 1.25 * 25 = 31.25 amperes
Temperature correction factor of 1/0 THWN Conductor for 40-750 C = 0.88 The corrected ampacity = 0.88 * 150 = 132 amperes
Service conductor for 225 Amperes load = 3/0 AWG neutral conductor for unbalanced load 110 = 3 AWG
Total 6 10 AWG RHH conductors can be installed in trade size ¾ EMT.
P = 120 * 15 = 1800 Number of receptacles = 1800 / 180 = 10 receptacles
These must be sealed to prevent the entry of gases or moisture in to the building.
Cord and plug connected equipment shall not exceed 80 percent of branch circuit rating 25 * 0.8 = 20 amperes
Ampacity of 2/0 THWN conductor in dry location = 195 A ( NEC Table 310.15 (B)(16)) Correction Ampacity at ambient temperature 450 C = 0.87 (NEC Table 310.15(B)(2)) Corrected Ampacity of conductor = 0.87 * 195 = 170 Amperes
3/0 THWN conductor ampacity in wet location (750C) = 175 Amperes ( NEC 310.15(B)(16)) Ambient temperature correction factor at 1080F = 0.85 ( NEC 310.15(B)(2)) raceway conductor bundle adjustment factor for 4 conductors= 0.8 ( NEC 310.15(B)(3)(a)) The conductor ampacity = 175 * 0.85 * 0.8 = 119 Amperes
Answer : 2/0 AWG Note : Service conductors that supply individual dwelling unit or single dwelling unit can have ampacity rating of 83% of service disconnect. The conductor ampacity for 200 A service disconnect = 0.83 * 200 = 166 amperes Refer : NEC Table 310.15(B)(16) 2/0 AWG with ampacity 175 amperes ( 750 C) is suitable as service conductor