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When do you derate wires in conduit I know the code says more than 3 current carrying conductors but is there a length of conduit run when you should start to derate?
Wiki User
∙ 14y ago
There are two things here to keep in mind. If you are trying to add more conductors to an existing conduit run use the cross sectional area of the conduit to see if more wires can be fitted. The second thing that's relates to length is the voltage drop at the load. To size the conduit work backwards from the load amperage to size the wires. If a long distance is involved a voltage drop calculation will be needed. Then select the conduit size to accommodate the wires recommended for that load amperage. The length of conduit run is not brought into the equation on de rating wire size it is always about keeping the voltage up at the load end of the run by increasing the wire size and selecting the proper conduit size for that wire.
Wiki User
∙ 14y ago
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How many amps for 14 wire how many amps for 12 wire?
#14 copper wire is rated at 15 amps, # 12 copper is rated at 20. The maximum capacity of any wire is 80% so remember to derate your current by multiplying the rated current by .8
What is the lug temperature rating of a breaker?
Look at the faceplate. There should be a 75˚C or 60˚C rating bsed on the temperature rating of the terminals. You have to use the lowest rating shown, ie, if you use 90˚C cable with a 75˚C termination, you have to derate the cable ampacity to a 75˚C. An example is look at 310.15(B)(16) in the 2011 NEC. 500kcmil cable is good for 430A in this table at 90˚C, if you had to derate to 75˚C, you loose 50 Amps and derate to 380A.
The ampacity of a number 12 aluminum wire with rhw insulation installed in a raceway that has 19 other wires is?
A #12 copper conductor with an insulation factor of 90 degrees C is rated at 20 amps. A #12 aluminium conductor with an insulation rating of 90 degrees C is rated at 15 amps. These conductors ratings only applies to three conductors in a raceway. To apply the derate to the conductor requires the size of the raceway. From 7 to 24 conductors in a raceway, both aluminium and copper conductor's ratings have to be reduced by .70, so 15 amps x .7 = 10.5 amps and 20 amps x .7 = 14 amps respectively.
How many computer outlets can go on a 10 amp circuit?
About 8 amps worth, if you derate the circuit for 100 percent duty cycle.
What is the max load on a 30 amp breaker?
The maximum load on a 30 amp breaker is 30 amps at 40 degrees C. If the ambient temperature is higher that 40 degrees C then the breaker will trip at a lower current. Keep in mind the breaker is a dual function device. On a short circuit the magnetic component will trip the breaker instantaneously. If you are designing a branch circuit for a load that is constantly on, code may require you to "derate" the branch by 20 percent so that the ordinary load is not at the rated load of the overcurrent protection.
How can you know cable size for a given current?
NEC code book table 310.15. Find the current you want to send through the conductor, look up which size conductor can handle that amperage. If you are pulling more than three current carrying conductors (hots and neutrals) in the same pipe you need to derate the listed ampacity of the wire. The percentages that you derate to are listed a couple pages before in the code. 4-6 current carrying conductors in the same raceway i believe is derated to 80% and i can't remember right off the top of my head the others.
How many current carrying conductors are allowed in a raceway before derating?
You can put three ccc's in a conduit (any size conduit) before you derate. Keep in mind that for single phase loads (lighting, receptacles) the neutral is also counted as a current carrying conductor. This derating factor does not apply to nipples 24 inches long or less. See NEC Table 310.15(B)(2)(a) for full details on derating regarding ccc's.
Do you derate for a three phase line and load conductors in the same conduit?
Yes, there will be a de-rate applied to this type of installation. In the electrical code book the amperage rating of conductors is for allowable ampacities for not more than three copperconductors in raceway or cable. This is based on an ambient temperature of 30 degrees C. If the ambient temperature of the conductors where the raceway is installed is over 30 degrees C the conductor amperages have to be reduced. Where the number of conductors are from 4 to 6 conductors in a raceway, the conductors amperage has to be reduced by .8
Amps on a 600 mcm copper?
475 amps, per NEC 310-16. Note that this is a maximum; there are many reasons to derate the current carrying capacity of the wire.
What is the current carrying capacity of a 18 awg stranded wire rated to 105 deg c 600 volts with PVC insulation?
The 2005 NEC allows 14 amps for 18 AWG wire in conduit, 18 amps in free air. Solid or stranded does not matter. There is no table that allows more current with higher insulation temperature rating. These values are good only up to 86 deg F ambient temperature, and must be derated according to table 310.16 or 310.17 if the ambient temp is above 86. You must also derate for more than 3 conductors in a raceway. I have not seen a PVC insulated wire rated to 105C. Is there such a thing?
Why is it necessary to derate cables when installed in a duct?
Heat cannot escape the duct as easily as in open air. This results in the same amount of current causing the cable to heat to a higher temperature.
Can you derate a truck in Louisiana to avoid a cdl?
It can be done, but you would actually have to reduce the vehicle's Gross Vehicle Weight Rating to 26,000 lbs. or less.. you're not going to derate a tandem.
How many amps for 14 wire how many amps for 12 wire?
#14 copper wire is rated at 15 amps, # 12 copper is rated at 20. The maximum capacity of any wire is 80% so remember to derate your current by multiplying the rated current by .8
The ampacity of a No. 12 aluminum wire with RHW insulation installed in a raceway that has 19 other wires is?
A #12 copper conductor with an insulation factor of 90 degrees C is rated at 20 amps. A #12 aluminium conductor with an insulation rating of 90 degrees C is rated at 15 amps. These conductors ratings only applies to three conductors in a raceway. To apply the derate to the conductor requires the size of the raceway. From 7 to 24 conductors in a raceway, both aluminium and copper conductor's ratings have to be reduced by .70, so 15 amps x .7 = 10.5 amps and 20 amps x .7 = 14 amps respectively.
What is the lug temperature rating of a breaker?
Look at the faceplate. There should be a 75˚C or 60˚C rating bsed on the temperature rating of the terminals. You have to use the lowest rating shown, ie, if you use 90˚C cable with a 75˚C termination, you have to derate the cable ampacity to a 75˚C. An example is look at 310.15(B)(16) in the 2011 NEC. 500kcmil cable is good for 430A in this table at 90˚C, if you had to derate to 75˚C, you loose 50 Amps and derate to 380A.
The ampacity of a number 12 aluminum wire with rhw insulation installed in a raceway that has 19 other wires is?
A #12 copper conductor with an insulation factor of 90 degrees C is rated at 20 amps. A #12 aluminium conductor with an insulation rating of 90 degrees C is rated at 15 amps. These conductors ratings only applies to three conductors in a raceway. To apply the derate to the conductor requires the size of the raceway. From 7 to 24 conductors in a raceway, both aluminium and copper conductor's ratings have to be reduced by .70, so 15 amps x .7 = 10.5 amps and 20 amps x .7 = 14 amps respectively.
The ampacity of NO 12 aluminum wire with RHW insulation installed in a raceway that has 19 other wires is what?
A #12 copper conductor with an insulation factor of 90 degrees C is rated at 20 amps. A #12 aluminium conductor with an insulation rating of 90 degrees C is rated at 15 amps. These conductors ratings only applies to three conductors in a raceway. To apply the derate to the conductor requires the size of the raceway. From 7 to 24 conductors in a raceway, both aluminium and copper conductor's ratings have to be reduced by .70, so 15 amps x .7 = 10.5 amps and 20 amps x .7 = 14 amps respectively.
