# Low Voltage Control Systems Wiring



## Shiseiji (Mar 27, 2015)

I've found this:  http://www.summittechs.com/images/Low Voltage Guide.pdf

Anyone know of another good document? I'm also looking for the "smart" way to run the in and out power leads and the control wires into conduit. Basic NM clamps? Rubber wire pinch connectors?

Thanks,

Ron


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## fahrphrompuken (Mar 27, 2015)

What type of conduit are you using? Sealtite, or Liquitite have dedicated fittings with standard box connector ends that provide a smooth edge free path. Also keeps dust, coolant, oil, etc out.

Looks like this....
http://www.hobby-machinist.com/gallery/20130413-180220.60680/full

Bill


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## Shiseiji (Mar 27, 2015)

Right now I've got plain old 3/4" emt dropping down from a metal box on the rafters on the gable wall to a cutoff mounted on 3/4" ply. Emt to the VFD to use the rubber end fitting where stranded wire can pass through.  None of that is sealed. I don't have the VFD in a box.  The control wiring is in 1/2" pipe to fit the exterior boxes. I'm not real pleased with the pipe edges. Neither am I pleased with the pvc box options as they don't have knockouts where i want them. But I am not inclined to get a conduit die for this little job. Though I suppose that could be my first lathe project LOL. I do have emt benders, 1/2 & 3/4". I know a pro job would have 3/4" every place, but . . . it's just one control wire. And the waterproof boxes I have on hand are 1/2."

When a pvc box is used, say to hold the VFD, after holes are drilled, are the fittings simply glued on? Or screw fitting/watertight type with a gasket/packing? Darned if I can find any recommended installation guidance other than the link I posted.

R


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## jim18655 (Mar 27, 2015)

Fittings into the PVC box would be held in place with a lock ring on the connector. I would recommend a flexible connection from the box to the conduit if your bending skills aren't real good. 1/2" is fine for any wire that fits based on conduit fill. If you  use metal conduit into the PVC box for the line voltage power you have to bond the conduits to ground since the box won't supply the bonding like a metal box would. Bond bushings are the typical method. If you open string the low voltage control wires and  just want to protect the wires where they enter the conduit Arlington Industries makes a white plastic bushing that slips on the bare end of the conduit.


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## JimDawson (Mar 27, 2015)

Shiseiji said:


> Neither am I pleased with the pvc box options as they don't have knockouts where i want them. But I am not inclined to get a conduit die for this little job



A step drill works just fine, you need some step drills anyway.  Most have 7/8 (1/2 inch knockout size) as the final step on the smaller ones.  They also make bigger ones for larger conduit sizes.  Look in the electrical section at the big box stores.  There are all kinds of sealed conduit connectors, again the big box store is a good resource.  Spend some time looking through all of the fittings.


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## icore3user (Mar 28, 2015)

Pipe edges after cutting should be reamed to clear all burs and nicks, ( Klein tools makes and ad on pipe reamer for screw drivers that covers 1/2" , 3/4" amd 1" EMT trade sizes , sold at big box stores ) . If you local box store does not carry slip on plastic bushings for EMT, you can always use a EMT set screw connector at each end with as plastic bushing on it to protect the control wires. If you are going to mount the VFD in a box and want the conduits coming in to be dust / oil tight, use rain tight compression fittings and step bit drill ( or hole saw ) the holes only as big as you need to the get them fitting to install with out to  much side play.


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## Shiseiji (Mar 28, 2015)

Bill, Jim & Jim, "Icore," thank you all. Bill, I'm getting a "You do not have permission to view media."  . . .  

My bending skills are so-so . . .  thanks much on the connector information. Have the step drill, so no worries there. The slip on bushing caries at the closest Big Box were so big they wouldn't fit into the connector, so they must be for the set screw connector which I was trying to avoid. Will do some more web research and simply order if necessary. LOL, have a bunch of flex, fittings & bushings for flex. Just was hoping to make it look/be better than that.  Been trying to avoid the "Never time to do it right, always time to do it over." 

Appreciate the help everyone. Any other ideas are always welcome. Still have to deal with the motor connector not being a NEMA L15-30 and either replacing the plug or just hard wiring the darn thing and be done with it. LOL, after getting a 3/4" box . . . does anyone ever have things just go smoothly? 

Ron


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