# 120V & 480V same conduit



## Guy (Nov 13, 2012)

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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## TomSpano (Jan 26, 2014)

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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## drumnut08 (Sep 23, 2012)

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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## Guy (Nov 13, 2012)

Thanks! TomSpano could you tell me which part of the code is it?


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## Guy (Nov 13, 2012)

drumnut08 said:


> . 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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## TomSpano (Jan 26, 2014)

Wiring methods. Don't have the book handy at the moment so I can't tell you what section.


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## drumnut08 (Sep 23, 2012)

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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## JRaef (Mar 23, 2009)

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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## Kryptes (Aug 6, 2013)

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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## ponyboy (Nov 18, 2012)

300.3(C)(1)

It's done all the time.


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## Big John (May 23, 2010)

Your 120V is very likely a Class 1 Remote-Control circuit and would fall under the restrictions of 725. Specifically check out 725.48


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## don_resqcapt19 (Jul 18, 2010)

drumnut08 said:


> . 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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## drumnut08 (Sep 23, 2012)

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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## drumnut08 (Sep 23, 2012)

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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## cc2kj (Aug 3, 2012)

Yes.... 600 vac insulation.


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## sparky970 (Mar 19, 2008)

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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## micromind (Aug 11, 2007)

JRaef said:


> 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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## Giorgio.g (Mar 31, 2013)

Guy said:


> Thanks! TomSpano could you tell me which part of the code is it?
> 
> 
> Sent from my iPhone using Tapatalk


Look in chapter 3 Article 3 hunit something:whistling2:


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## GEORGE D (Apr 2, 2009)

JRaef said:


> 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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## Cl906um (Jul 21, 2012)

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


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## Cl906um (Jul 21, 2012)

GEORGE D said:


> 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.


sh8rt distance yes. Mixed in cable tray no.


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## T&K (Jun 18, 2012)

I'm confused as to what is so dangerous about running emergency circuits in the same conduit with circuits that are not on the emergency backup system. And further more, just because an "engineer" has a spec for something on a set of drawings, doesn't mean that it is what is needed. I've found most of the "engineered" drawings that I have looked at have been so over-engineered its almost comical.


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## Cl906um (Jul 21, 2012)

T&K said:


> I'm confused as to what is so dangerous about running emergency circuits in the same conduit with circuits that are not on the emergency backup system. And further more, just because an "engineer" has a spec for something on a set of drawings, doesn't mean that it is what is needed. I've found most of the "engineered" drawings that I have looked at have been so over-engineered its almost comical.


If you worked on a ups or emergen c backed up system the potential is pretty high.


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## Awg-Dawg (Jan 23, 2007)

T&K said:


> I'm confused as to what is so dangerous about running emergency circuits in the same conduit with circuits that are not on the emergency backup system.


 I don't think that it is dangerous, it is a matter of compromising the "emergency" system.

If the normal system faults for whatever reason the emergency system is isolated from that problem.


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## T&K (Jun 18, 2012)

cl219um said:


> If you worked on a ups or emergen c backed up system the potential is pretty high.


Are you talking about a circuit that is being backed up by an emergency generator?


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## T&K (Jun 18, 2012)

Awg-Dawg said:


> I don't think that it is dangerous, it is a matter of compromising the "emergency" system.
> 
> If the normal system faults for whatever reason the emergency system is isolated from that problem.


I guess I can see that reasoning. Though I think it's taking things overboard, unless we are talking about life safety circuits. However, to run two separate conduits to a commercial kitchen so you can keep the refrigerator circuit (on backup system) separate from the countertop outlets circuit (not on back up system) that are right next to the refrigerator, seems a touch over engineered and far from dangerous.


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## Awg-Dawg (Jan 23, 2007)

T&K said:


> I guess I can see that reasoning. Though I think it's taking things overboard, unless we are talking about life safety circuits. However, to run two separate conduits to a commercial kitchen so you can keep the refrigerator circuit (on backup system) separate from the countertop outlets circuit (not on back up system) that are right next to the refrigerator, seems a touch over engineered and far from dangerous.


 There is quite a bit of difference between those.

Here is one link that shows the difference.


http://static.schneider-electric.us/assets/consultingengineer/appguidedocs/section10_0307.pdf


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## charliev (Apr 24, 2012)

drumnut08 said:


> 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 !


I think you should go back and read what Don said. He was making a point of clarifying that Art. 700 systems do in fact require separate wiring but not Art. 701 or 702 systems. Art. 700, 701 and 702 systems all have different uses and requirements.


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## Aegis (Mar 18, 2011)

Up here we can't have 347v and 120v in the same conduit. Can you guys in the States have 277v and 120v in the same conduit for lighting?


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## Awg-Dawg (Jan 23, 2007)

Aegis said:


> Can you guys in the States have 277v and 120v in the same conduit for lighting?


 
For the most part, yes we can.

What are you guys worried about?


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## T&K (Jun 18, 2012)

Awg-Dawg said:


> There is quite a bit of difference between those.
> 
> Here is one link that shows the difference.
> 
> http://static.schneider-electric.us/assets/consultingengineer/appguidedocs/section10_0307.pdf


Like I said, I'll agree with keeping them separate when dealing with life safety and legally required systems. I guess I didn't realize that is the types of circuits the thread was referring to. I, for instance, am currently working on a project that has partial generator backup for 9000 square foot multi family dwellings. There is 3 HVAC units for the building, and they are being piped in the slab. The generator is only going to back up the gas furnace portion of the system for heat, but not the condensers for air conditioning. I was trying to figure out what was so dangerous about having a back up generator supplied furnace circuit in the same pipe with a condenser circuit.


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## T&K (Jun 18, 2012)

cl219um said:


> If you worked on a ups or emergen c backed up system the potential is pretty high.


The potential for what? For having a conduit with two circuits in it, and only one of them having power on it? Please explain.


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## Awg-Dawg (Jan 23, 2007)

T&K said:


> Like I said, I'll agree with keeping them separate when dealing with life safety and legally required systems. I guess I didn't realize that is the types of circuits the thread was referring to. I, for instance, am currently working on a project that has partial generator backup for 9000 square foot multi family dwellings. There is 3 HVAC units for the building, and they are being piped in the slab. The generator is only going to back up the gas furnace portion of the system for heat, but not the condensers for air conditioning. I was trying to figure out what was so dangerous about having a back up generator supplied furnace circuit in the same pipe with a condenser circuit.


 
I agree with you.

And, I think the code allows it.


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## Aegis (Mar 18, 2011)

Awg-Dawg said:


> For the most part, yes we can. What are you guys worried about?


It's funny how in Canada we're all trained this way. When an apprentice asks "Can you have two different voltages in the same pipe?" They'll get a look from some electricians as if they said something stupid. Meanwhile in the States all is well with doing it lol

The only reason that sits right with me personally is organization/safety. I don't work live but some guys will (hacks/morons) especially with 120v. If one of these guys is mucking around in a JB and there's also live 347/600v kicking around in there, they could do some damage. So basically it's to protect those kinds of people.

I find so many problems with neutrals on 120v ccts, like 5 ccts with one neutral/using ground as neutral etc. Throwing a higher voltage into it would make it even worse, who knows what these guys would come up with.

You guys have less hacks down there? lol


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## Awg-Dawg (Jan 23, 2007)

Aegis said:


> I find so many problems with neutrals on 120v ccts, like 5 ccts with one neutral/using ground as neutral etc. l


 Im sure that happens everywhere.


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## Guy (Nov 13, 2012)

What about 24vac and 580vac?


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## micromind (Aug 11, 2007)

Guy said:


> What about 24vac and 580vac?
> 
> 
> Sent from my iPhone using Tapatalk


Provided that all wire is rated for 600 volts, it'd be completely legal.


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## Guy (Nov 13, 2012)

micromind said:


> Provided that all wire is rated for 600 volts, it'd be completely legal.



I am sorry I meant 24dc and 120 ac


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## Southeast Power (Jan 18, 2009)

drumnut08 said:


> . 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 .


Ok, would you expect both sources to be on at the same time?


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## Mate (Sep 5, 2009)

Aegis said:


> Up here we can't have 347v and 120v in the same conduit. Can you guys in the States have 277v and 120v in the same conduit for lighting?


Because we have common sense over here. They can mix 480 with 120 but can't land a circuit in a house without arc-faulted it.


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## sparky970 (Mar 19, 2008)

cl219um said:


> sh8rt distance yes. Mixed in cable tray no.


 
What?


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## sparky970 (Mar 19, 2008)

Guy said:


> I am sorry I meant 24dc and 120 ac
> 
> 
> Sent from my iPhone using Tapatalk


 
You could, but you shouldn't


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## Cl906um (Jul 21, 2012)

sparky970 said:


> What?


in control cabinets vfd wires sometimes have to run together for a short distance. in cable tray you have to use shielded cable so it doesnt pick up the 60 hertz frequency induction from the non drive cables.


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## sparky970 (Mar 19, 2008)

cl219um said:


> in control cabinets vfd wires sometimes have to run together for a short distance. in cable tray you have to use shielded cable so it doesnt pick up the 60 hertz frequency induction from the non drive cables.


 
No you don't


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## don_resqcapt19 (Jul 18, 2010)

drumnut08 said:


> 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 !


What am saying is what you are calling "emergency" is not what the code calls it. Yes, the code says normal and emergency circuits must be kept separate. 

I have worked many jobs where the job specs did not require the legally required standby and optional standby circuits to be kept separate from the normal circuits. The code does not require that either.


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## Cl906um (Jul 21, 2012)

sparky970 said:


> No you don't


yeah you do


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## sparky970 (Mar 19, 2008)

cl219um said:


> yeah you do


And your authority telling you this is......


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## CanadianSparky (May 10, 2011)

Mate said:


> Because we have common sense over here. They can mix 480 with 120 but can't land a circuit in a house without arc-faulted it.


I wouldn't be surprised if it became standard here too. Money will always prevail.


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## Cl906um (Jul 21, 2012)

sparky970 said:


> And your authority telling you this is......


the instruction book that comes with vfd's. not a code book. sometimes you have to go by instructions. tells me to run the motor leads in their own conduit. i am saying if you are running tray wire to use shielded cause that is the same as its own raceway... all though listing and labeling is an article in nec.


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## sparky970 (Mar 19, 2008)

cl219um said:


> the instruction book that comes with vfd's. not a code book. sometimes you have to go by instructions. tells me to run the motor leads in their own conduit. i am saying if you are running tray wire to use shielded cause that is the same as its own raceway... all though listing and labeling is an article in nec.


A recommendation is not a requirement.


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## Cl906um (Jul 21, 2012)

sparky970 said:


> A recommendation is not a requirement.


certain drives for motors require this for proper operation. if a certain motor needs to be tweaked to a specific rpm, and keep it, say for a paper machine, i for one would follow the " recommendations." guess i am anal that way..


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## guest (Feb 21, 2009)

cl219um said:


> in control cabinets vfd wires sometimes have to run together for a short distance. in cable tray you have to use shielded cable so it doesnt pick up the 60 hertz frequency induction from the non drive cables.


Absolutely. I made that mistake only once..routed my unshielded motor leads too close to the unshielded control wires (a run of only 3 feet) and BOTH drives, even the one that was off, would false trigger and act erratically. Very dangerous as stopping one machine frequently made the other one start or "bump" without warning. 



sparky970 said:


> No you don't





cl219um said:


> yeah you do





sparky970 said:


> And your authority telling you this is......





cl219um said:


> the instruction book that comes with vfd's. not a code book. sometimes you have to go by instructions. tells me to run the motor leads in their own conduit. i am saying if you are running tray wire to use shielded cause that is the same as its own raceway... all though listing and labeling is an article in nec.





sparky970 said:


> A recommendation is not a requirement.


You better hope I never have to inspect any of your work. Following manufacturer instructions is part of making an installation Code-Compliant. 

And how did you get recommendation from that? He said instructions. 

Finally, failure to follow proper instructions can void any warranty on the drives or even the motors. And you'd end up with a very pissed-off customer when his installation malfunctions and/or fails inspection. 



cl219um said:


> certain drives for motors require this for proper operation. if a certain motor needs to be tweaked to a specific rpm, and keep it, say for a paper machine, i for one would follow the " recommendations." guess i am anal that way..


And you are correct. :thumbup:


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## Carultch (May 14, 2013)

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


See this discussion on the topic:
https://www.youtube.com/watch?v=8YnC-Suw2Zs

In order to mix different systems wiring in the same raceway:
1. ALL wiring has to have an insulation rating for the largest nominal voltage between any pair of wires in the raceway.
2. The neutral wiring of both systems must be separately identified in an approved manner.

Most wiring available is rated for 600V, so it isn't that difficult to satisfy #1.

My recommendation to satisfy #2, is to use white wire for the 120V system's neutral, and gray wire for the 480V system neutral. It isn't a code requirement to follow this convention, but it is what I would follow, even if I weren't running them in the same raceways/enclosures.

Wire size #4 and physically larger, can be taped at terminations for identification (instead of using colored wire). If you are doing this, make sure to do this also at any point you can open a lid and access the wire.


If going by code alone, that is all the rules you have to follow for doing this. This does not guarantee that your wiring will work properly, as one system can induce signals into the other system. It is best if you keep each system's wiring bundled together, separate from the other, such that the magnetic fields balance. It is also best, if you make sure that all equipment is able to withstand any erroneous 480 Volts that may occur.


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## sparky970 (Mar 19, 2008)

cl219um said:


> certain drives for motors require this for proper operation. if a certain motor needs to be tweaked to a specific rpm, and keep it, say for a paper machine, i for one would follow the " recommendations." guess i am anal that way..


I don't disagree, but there is a lot of installs from years past where VFD motors are fed with regular tray cable mixed with other stuff. My work is 95% pulp and paper mills. Most older installs do not use shielded cable. Plenty of new stuff is still installed without VFD cable, typically small hp motors. I will put it in if it's spec, but if it is not, I won't. I would never get work that way.


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## Carultch (May 14, 2013)

Guy said:


> I am sorry I meant 24dc and 120 ac
> 
> 
> Sent from my iPhone using Tapatalk



The code now requires a physical separator, if you are going to share a raceway with DC and AC.


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## ponyboy (Nov 18, 2012)

Carultch said:


> The code now requires a physical separator, if you are going to share a raceway with DC and AC.


For real? I don't see that happening


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## Cl906um (Jul 21, 2012)

sparky970 said:


> I don't disagree, but there is a lot of installs from years past where VFD motors are fed with regular tray cable mixed with other stuff. My work is 95% pulp and paper mills. Most older installs do not use shielded cable. Plenty of new stuff is still installed without VFD cable, typically small hp motors. I will put it in if it's spec, but if it is not, I won't. I would never get work that way.


well, thats kinda backpedaling. the paper mill i had worked at recently just starting doing it the right way with shielded cable too. they were actually engineering it without for years. its not new technology, but were going to change all the synced dc motors to ac drive that requires them to operate at an exact rpm. money is tight i guess for the other motors that arent so technical.


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## Guy (Nov 13, 2012)

sparky970 said:


> I don't disagree, but there is a lot of installs from years past where VFD motors are fed with regular tray cable mixed with other stuff. My work is 95% pulp and paper mills. Most older installs do not use shielded cable. Plenty of new stuff is still installed without VFD cable, typically small hp motors. I will put it in if it's spec, but if it is not, I won't. I would never get work that way.




What are the advantages of using VFD cable instead of regular wire?


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## sparky970 (Mar 19, 2008)

Can you show me in the AB Powerflex 700 where it shows a requirement for motor cabling?


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## Cl906um (Jul 21, 2012)

sparky970 said:


> Can you show me in the AB Powerflex 700 where it shows a requirement for motor cabling?


Page 8 in the installation instructions it tells you what power and control wires are to be shielded. We have installed abb drives mostly, but looked up this for you just for fun. The PDF is available online.


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## T&K (Jun 18, 2012)

cl219um said:


> If you worked on a ups or emergen c backed up system the potential is pretty high.


I still haven't been explained the danger in this cl219um...


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## di11igaf (Jan 1, 2012)

Carultch said:


> See this discussion on the topic:
> https://www.youtube.com/watch?v=8YnC-Suw2Zs
> 
> In order to mix different systems wiring in the same raceway:
> ...


Agree, that requirement is only for the ground conductor though.


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