vfd load side conductors

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tim89s

Member
Location
Brush Prairie WA
The customer wants to add a vfd to an existing exhaust fan. I haven't seen the vfd, the HVAC company is providing. My question is can I run the load side conductors of the vfd in the same conduit, for approx 8', with other conductors. The other conductors wouldn't be the line conductors of the vfd.

Thanks for your time
Tim
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
I think most everyone on here will tell you it's technically not right, that it should be shielded VFD cable or thhn in metal conduit all by itself. The reality is I've seen a lot of shared load side VFD circuits in the same conduit for a lot longer than 8 feet. The drives and conductors weren't failing left and right and most have been plugging right along for years without any issues.

Long story short, I wouldn't worry about it myself, although I don't make it a common practice to share conduits with VFD conductors.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
As long as the conductors of the 8' overlap do not feed sensitive equipment, such as audio electronics, you should be OK. Although dimmers on lighting circuits (any phase controlled SCR switching) might have a problem too.
 

Dexie123

Senior Member
As long as the conductors of the 8' overlap do not feed sensitive equipment, such as audio electronics, you should be OK. Although dimmers on lighting circuits (any phase controlled SCR switching) might have a problem too.

Is this a code or just a design restriction/issue?
 

ADub

Senior Member
Location
Midwest
Occupation
Estimator/Project Manager
Could be a code issue if you apply the installation manual as part of the NEC. Line and load reactors are recommended on some of the VFDs we use. It may depend on the wording in that manual. The manual also says "read entirely" or words to that affect.

Yeah and drive manufacturers also likely recommend you use their brand of vfd cable. Don't fall for that one


Sent from my iPhone using Tapatalk
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
it is not a code issue.

whether it is advisable to do so is another story. personally, I would not get real excited about running them a short distance in the same conduit.
 
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