Multiple voltage cables in one conduit

[smarteng]

Hi Guys,

Can we run Radio cables, DC (12 V) and 12 AWG (3ph, 480V for 1 hp motor) cables in one 1" conduit. What will be effect of running them in one conduit. I understand it's not good engineering,but if it's the only way, what precautions can I take to minimize if not completely avoid interference, noise etc.

Conduit Size: 1"
Conduit Run : Approximately 200'
Cable inside conduit: 3- CM/Class3 cables, 1-12v dc cable, 1 (4 conductors) for 3ph, 480V, 1.8amp, 1hp motor.

Thank you so much.

 

[jaggedben]

You probably can't run a class 3 cable in the same conduit as a 480V circuit, unless that's some kind of class 3 cable that's rated for upwards of 480V. There may be further restrictions if it's actually a class 3 circuit, see Article 725.

The size issue is independent of the voltage issue. I'd wager you'd be okay on the size, unless that's some ridiculous oversize cable.

 

[tallgirl]

What is the 12VDC cable for? If it's just power, look at whatever is using that power has for an input filter, or how tolerant it is of noise. Because you're going to have noise ...

 

[drktmplr12]

Hi Guys,

Can we run Radio cables, DC (12 V) and 12 AWG (3ph, 480V for 1 hp motor) cables in one 1" conduit. What will be effect of running them in one conduit. I understand it's not good engineering,but if it's the only way, what precautions can I take to minimize if not completely avoid interference, noise etc.

Conduit Size: 1"
Conduit Run : Approximately 200'
Cable inside conduit: 3- CM/Class3 cables, 1-12v dc cable, 1 (4 conductors) for 3ph, 480V, 1.8amp, 1hp motor.

Thank you so much.

Perhaps using armored 4 conductor #12 would help here since it is technically in its own raceway and therefore physically separated from the. the armor should effectively keep the emf from the motor relegated to the cable, but not completely. hard to say if it will all fit in a 1".

 

[Jraef]

All wires would be required to have the same level of insulation as the highest level [300.3(C)(1)], so you would need 600V rated wire insulation for the Class 2 and 3 circuits (assuming the 12VDC would be Class 2), even though your actual circuit voltage would be far lower. Then because of the presence of 480VAC circuits, you will want your LV circuits to be shielded. Can you get 600V rated shielded instrumentation cable? Yes, but you may need to look around.

 

[texie]

Hi Guys,

Can we run Radio cables, DC (12 V) and 12 AWG (3ph, 480V for 1 hp motor) cables in one 1" conduit. What will be effect of running them in one conduit. I understand it's not good engineering,but if it's the only way, what precautions can I take to minimize if not completely avoid interference, noise etc.

Conduit Size: 1"
Conduit Run : Approximately 200'
Cable inside conduit: 3- CM/Class3 cables, 1-12v dc cable, 1 (4 conductors) for 3ph, 480V, 1.8amp, 1hp motor.

Thank you so much.

Class 2 and 3 circuits can not be run in the same raceway as power circuits no matter what kid of insulation is used. Study Article 725.

 

[hbiss]

Hi Guys,

Can we run Radio cables, DC (12 V) and 12 AWG (3ph, 480V for 1 hp motor) cables in one 1" conduit.

No! Use separate conduits. Nothing to do with interference, you are not allowed to run LV with line voltage.

-Hal

 

[augie47]

No! Use separate conduits. Nothing to do with interference, you are not allowed to run LV with line voltage.

-Hal

Pretty broad statement on it's own. The ability to share raceways is dependent on a number of conditions.

 

[hbiss]

Pretty broad statement on it's own. The ability to share raceways is dependent on a number of conditions.

Very few and out of those even fewer that can actually be done.

-Hal

 

[drktmplr12]

armored cable would likely not fit it seems.

 

[smarteng]

Thank you all. Really appreciate the help. We end up not doing so to keep compliance with 725.