0
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
In general, you should start to derate when you have more than 3 current carrying conductors in a conduit. The length of the conduit run itself does not determine when you should derate. Stick to the guidelines provided in the electrical code for derating calculations to ensure safe and compliant installations.
Add your answer:
Earn +20 pts
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.
How many amps for 14 wire how many amps for 12 wire?
A 14-gauge wire can typically carry up to 15 amps of current, while a 12-gauge wire can handle up to 20 amps. It's important to follow the manufacturer's guidelines and electrical codes when determining the maximum current for a specific wire size.
What is the lug temperature rating of a breaker?
The lug temperature rating of a breaker typically refers to the maximum temperature that the lug (terminal) on the breaker can safely withstand without being damaged. This rating ensures safe and reliable operation of the breaker under normal operating conditions. It is important to adhere to the lug temperature rating to prevent overheating and potential damage to the breaker.
The ampacity of a number 12 aluminum wire with rhw insulation installed in a raceway that has 19 other wires is?
The ampacity of a number 12 aluminum wire in that scenario would typically be around 25 amps, considering standard ambient temperature and wiring conditions. It's important to consult the NEC or a qualified electrician to ensure compliance with local electrical codes and regulations, as specific factors can affect the ampacity calculations.
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.
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.
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.
What is the derating?
Derating factor depends on ambient temperature & how u r laying the cable ie., in Air,Duct,Burried. normally the current carring capacity of a perticular cable is calculated at 40*c, but if u lay the cable in air then it includes the temparture around it,if it increases more the 40*c then the conductor gets heated up by increasing the resistance in it thus the current carring capacity of a given cable decreases, so we will derate the cable The derating factor of induction motor is the ratio of the calculated output power to the rated power
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.
How many amps for 14 wire how many amps for 12 wire?
A 14-gauge wire can typically carry up to 15 amps of current, while a 12-gauge wire can handle up to 20 amps. It's important to follow the manufacturer's guidelines and electrical codes when determining the maximum current for a specific wire size.
