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Wire size is based on the amperage that the load requires. For an accurate answer the motor amperage is needed. That said you can get an approximate figure by this method. 1 HP = 746 watts. This formula for amperage when HP is known. HP x 746/1.73 x Voltage x %Eff x pf. Use a Efficiency % at 90 and a power factor of .85. A horse power of 5 x 746 = 3730/1.73 x 220 x 90% x .85 = 12.81 amps. Code states that motor supply conductors have to be 125% of the full load amps = 16 amps. Code also states that conductors can only be loaded to 80% on continuous load which a motor falls into. A #12 copper wire 90 degree insulation is rated at 20 amps x 80% = 16 amps. A #12 wire will do the job. It will need a 40 amp three pole breaker, 50 amp non time delay fuse or a 30 amp time delay fuse to feed the motor.
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∙ 14y ago
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∙ 12y agoMost common voltages for this applications: 208 vac grounding conductor 1/0 copper, 230 vac grounding conductor 1/0 copper, 460 vac grounding conductor #3 copper, this assumes breaker usage as over current device. Use of fuses would affect wire size.
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Again, to answer this question the voltage of the motor is needed.
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∙ 13y agoNEC table 430.250 says this motor pulls 61 amps at 460 volt. 61 amps X125% =76.25 amps. NEC table 310.15(B)(16) list #4 THWN good for 85 amps. Use # 4 THWN with a 175 amp breaker or 110 amp dual element fuse.
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∙ 10y agoWire size and breaker size is based on the amperage drawn by the motor. Always use the motor's nameplate amperage before using the equation.
The equation for amperage when the HP is known is Amps = HP x 746/1.73 x volts x % eff x pf.
A standard motor's efficiency between 5 to 100 HP is .84 to .91.
A standard motor's power factor between 10 to 100 HP is .86 to .92.
Amps = 100 x 746 = 74600/ 1.73 x 240 x .91 x .92 = 74600/348 = 214 amps.
Feeders for motor loads has to be rated at 125% of the motors full load amps. The wire rating will be 214 x 125% = 267 amps.
A 250 MCM copper conductor with an insulation factor of 90 degrees C is rated at 290 amps.
For conductor protection of the motor feeders, non time delay fuses 600 amp, time delay fuses 350 amps and a breaker has to be rated at 250% of the motors full load amps. The nearest breaker for this amperage will be a 500 amp breaker.
As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
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∙ 12y agoTable 430.250 list this motor at 62 amps. 62 times 125%= 77.5 amps. This would reuire a wire size of #4 copper THWN.
Wiki User
∙ 7y agoIt depends on the supply voltage, the type of conductor, the number of cores, the method of installation, etc.
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Can you replace a three phase motor 3 Hp RPM 1420 with a single phase motor for a planer?
Probably not. The single phase three horse power motor will be much larger in physical size than its three phase counterpart, and will probably not fit.
What is the cable size for 600V 3 phase ac motor?
you need the current of motor or the KW/HP rating
What size motor do you need to run a compressor 2 stage 80 gallon tank i have a 3 phase on it and want to change motor?
You probably need a 5hp or 7hp motor. Look for HP rating o the 3 phase motor and select the same for single phase. 3 phase has same power but is more efficient at electricity use. Also consider a 3 phase converter. It allows a 3 phase motor to run on single phase service.
Can a 380volt's 3 phase motor can be converted to 230volt's three phase motor?
Only if you want to damage it. "277" Volt 3-phase will usually mean 277 from each phase to neutral, and 480 from phase to phase. By "230 3-phase", you likely mean 120 phase-to-neutral, and 208 phase-to-phase. If you really mean 230, then you are probably NOT talking about a three phase motor.
By how many amps may a three phase motor exceed its data plate rating?
On a normal three phase motor on the nameplate there is a value in the S.F. box. This is the service factor. Depending on the size of the motor this value will vary. Smaller size motors usually have a service factor of 1.15.See related links below.
What is the cable size for 1.5KW 3 phase induction motor?
Sir, what is the cable size for 1.5kw 3phase induction motor 400v?
Can you replace a three phase motor 3 Hp RPM 1420 with a single phase motor for a planer?
Probably not. The single phase three horse power motor will be much larger in physical size than its three phase counterpart, and will probably not fit.
Can you run 22 kw 600v 3 phase induction motor?
Yes this size motor can be operated by bringing a 600 volt three phase supply to it.
What is the cable size for 600V 3 phase ac motor?
you need the current of motor or the KW/HP rating
What size motor do you need to run a compressor 2 stage 80 gallon tank i have a 3 phase on it and want to change motor?
You probably need a 5hp or 7hp motor. Look for HP rating o the 3 phase motor and select the same for single phase. 3 phase has same power but is more efficient at electricity use. Also consider a 3 phase converter. It allows a 3 phase motor to run on single phase service.
Minimum breaker size 60 horsepower motor?
Need motor voltage, amperage and phase to give you an anwer.
How do you select earthing conductor size of any motor panel etc?
The ground wire size is determined from the current carrying capacity of the motor feeders.
Can a 380volt's 3 phase motor can be converted to 230volt's three phase motor?
Only if you want to damage it. "277" Volt 3-phase will usually mean 277 from each phase to neutral, and 480 from phase to phase. By "230 3-phase", you likely mean 120 phase-to-neutral, and 208 phase-to-phase. If you really mean 230, then you are probably NOT talking about a three phase motor.
By how many amps may a three phase motor exceed its data plate rating?
On a normal three phase motor on the nameplate there is a value in the S.F. box. This is the service factor. Depending on the size of the motor this value will vary. Smaller size motors usually have a service factor of 1.15.See related links below.
How do you select fuse for motor?
There should be a label on the motor with that information. If not, have the motor checked by a qualified electrician or electronic technician to determine the proper fuse size.
What size capacitor is needed to start a 1 hp 14 amp 110V motor?
A single phase motor does not actually require a capacitor. This device is only needed when a split phase motor is utilised. A split phase motor needs a device to regulate the power factor associated with the split phase.
What size wire do you need for 2HP motor with 120 volts?
12/2 with ground.
