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Discussion Starter · #1 ·
I am wiring a actuator valve that has 480Vac power and 120vac control wiring. I was wondering if I could wire them through the same conduit.


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Was just reviewing this section of the code
Book last night; I do believe your good. Conductors with over 600v with conductors under 600v is a no go unless the lower voltage line is a control line for the high voltage motor, or something to that effect
 

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Guy said:
I am wiring a actuator valve that has 480Vac power and 120vac control wiring. I was wondering if I could wire them through the same conduit. Sent from my iPhone using Tapatalk
. Yes , as long as it's 600 volt rated insulation . You don't want to mix normal and emergency power systems in the same raceway , however .
 

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Discussion Starter · #4 ·
Thanks! TomSpano could you tell me which part of the code is it?


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Discussion Starter · #5 ·
. Yes , as long as it's 600 volt rated insulation . You don't want to mix normal and emergency power systems in the same raceway , however .

What do you mean by emergency power?


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Guy said:
What do you mean by emergency power? Sent from my iPhone using Tapatalk
. I mean from a standby source , such as a generator , or UPS system . Normal power comes from the grid . Emergency ( standby ) power is generated separate from the grid ( generator ) . These two systems should never share a common raceway .
 

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Aside from the insulation rating of the conductors, there is a good reason to avoid this, but it is not a code issue. Current flow in the 480V conductors can induce current to flow in the 120V conductors. It will not usually be much, but depending on the nature of the 120V load, it might cause problems. If you are looking at a motorized valve actuator, it probably will not be an issue. But if the 120V is a control signal going into a more sensitive device, like a digital input on an electronic controller, the induced current may cause it to malfunction. A common result is this; the signal tells someting to turn on, when it does, the 480 flows, inducing a current on the control signal conductors. Then the control signal is removed to tell the load to shut down, but the induced current keeps the digital signal energized enough to interfere with the Stop command and it keeps runnin. There are ways to fix that after the fact, but it's better to avoid it in the first place.
 

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JRaef is correct that it is best to avoid when possible. We have had more then a few service calls to troubleshoot equipment because that was the wiring practice of another contractor.
 

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. I mean from a standby source , such as a generator , or UPS system . Normal power comes from the grid . Emergency ( standby ) power is generated separate from the grid ( generator ) . These two systems should never share a common raceway .
That is not correct...emergency power is only the power that is installed per Article 700. Conductors installed per the rules of Article 700 must be separate from conductors of other systems. Conductors from other standby power sources are not required to be kept separate from conductors from the normal power source. Even conductors for legally required standby systems (Article 701) are not required to be separate from conductors of other systems.
701.10 Wiring Legally Required Standby Systems. The legally required standby system wiring shall be permitted to occupy the same raceways, cables, boxes, and cabinets with other general wiring.
 

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don_resqcapt19 said:
That is not correct...emergency power is only the power that is installed per Article 700. Conductors installed per the rules of Article 700 must be separate from conductors of other systems. Conductors from other standby power sources are not required to be kept separate from conductors from the normal power source. Even conductors for legally required standby systems (Article 701) are not required to be separate from conductors of other systems.
. Whatever ? It's still a bad practice and the NEC is minimal standard by the way , lol ! Sometimes , common sense prevails over what is legal , no ?
 

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don_resqcapt19 said:
That is not correct...emergency power is only the power that is installed per Article 700. Conductors installed per the rules of Article 700 must be separate from conductors of other systems. Conductors from other standby power sources are not required to be kept separate from conductors from the normal power source. Even conductors for legally required standby systems (Article 701) are not required to be separate from conductors of other systems.
no offense don , but in not quite sure of your background , but if you think , you're going to combine normal and emergency circuits in a common raceway on an engineered / heavily inspected commercial project , you're sadly mistaken ! Most job specifications mandate that normal and emergency systems be separate . Sometimes , the NEC standards are flat out dangerous !
 

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We put a lot of start/stop controls in the same conduit as the motor feeders, as long as the motor feeder wire is less than 1/0. Very common for small hp motors
 

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motors and controls.........
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Aside from the insulation rating of the conductors, there is a good reason to avoid this, but it is not a code issue. Current flow in the 480V conductors can induce current to flow in the 120V conductors. It will not usually be much, but depending on the nature of the 120V load, it might cause problems. If you are looking at a motorized valve actuator, it probably will not be an issue. But if the 120V is a control signal going into a more sensitive device, like a digital input on an electronic controller, the induced current may cause it to malfunction. A common result is this; the signal tells someting to turn on, when it does, the 480 flows, inducing a current on the control signal conductors. Then the control signal is removed to tell the load to shut down, but the induced current keeps the digital signal energized enough to interfere with the Stop command and it keeps runnin. There are ways to fix that after the fact, but it's better to avoid it in the first place.
I've run tons of 480 and 120 in the same pipe, usually a start-stop and a motor.

If the motor is not too big and the run is not too long, you'll be ok. But I know for a fact that a 2HP 480V 3Ø motor in the same pipe 650' long with 120 controls absolutely will hold an ice cube relay coil in even if it's completely disconnected from the source. Grounding the coil will make it drop out though (can you guess what my solution was.....lol).

I also know that an unterminated spare wire in a long run with a 480 motor will bite you pretty hard..........
 

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Aside from the insulation rating of the conductors, there is a good reason to avoid this, but it is not a code issue. Current flow in the 480V conductors can induce current to flow in the 120V conductors. It will not usually be much, but depending on the nature of the 120V load, it might cause problems. If you are looking at a motorized valve actuator, it probably will not be an issue. But if the 120V is a control signal going into a more sensitive device, like a digital input on an electronic controller, the induced current may cause it to malfunction. A common result is this; the signal tells someting to turn on, when it does, the 480 flows, inducing a current on the control signal conductors. Then the control signal is removed to tell the load to shut down, but the induced current keeps the digital signal energized enough to interfere with the Stop command and it keeps runnin. There are ways to fix that after the fact, but it's better to avoid it in the first place.
What about vfd inputs? Like control cabinets where everything is stuffed into panduit together. I have a customer with up to 10-20 vfd's in a cabinet.
 

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Black, red, blue, and white. Brown, orange, yellow, gray. Same class wiring. Mix it wherever accepted in tye code.
 
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