Can I run 440v and 110v in the same conduit?

I have heard something about magnetic field interference , does anybody there know where can i find some electrical wiring rules or guide?

thanks in advanced

 

All the wiring should be rated 600V. Remember that magnetic field strength is proportional to current and number of turns or passes. (The number of turns has the effect of counting the same current repeatedly.) Voltage is irrelevant. As long as the insulation is adequate, conductors have no way of "knowing" what voltage is present in adjacent conductors, only the current and the rate of change of the current.

 

Yes, if they are fed from the same supply. And yes you will pick up inductive noise from the 440v to the 110v. You should base your decision on what the 110v supply is for. If it supplying electronic equipment then don't run them in the same conduit.

 

Sir:
I would call an electrician. As a rule we do not run control and power in the same pipe or raceway. This is not always the case, but The National Electric Code is the place to go.

There are times when control and power meet. Say in a panel or new work going in next to old work. In this case cross the wires at 90' (degrees)

In my world 480V 3p (277) is most of the time power to run motors.

And 120 or (208) 3p is used for PLC, dc power supplies, lights, control and I/O.

The only place that I have ever seen them run together is a 90volt dc brake that was put on a 230v 3p motor.

I would say NO but check the NEC

 

See NEC300-3(c)(1)

 

There is nothing in the NEC to prevent running 440 and 110 in the same raceway providing that the wires are all rated for the higher voltage.
However as was said there are times when it is not a good engineering practice as the inductive coupling between the wires can cause problems with
PLC inputs. More and more installation specs call for separate raceways for motor and control wiring for this reason, and it is a good idea to do so.

Jeff.

 

>>Voltage is irrelevant. As long as the insulation is adequate, conductors have no way of "knowing" what voltage is present in adjacent conductors, only the current and the rate of change of the current. >>

This statement is not correct. There is capacitive(electrostatic) coupling between these two cables based on voltage difference, frequency, and capacitance between the cables. In the case of power cables under 600V, this effect is generally negligible but in the case of power to signal cables or signal to signal cables, it may not be. The same applies to magnetic(inductive) coupling. In the case of power cables, the effect is generally negligible but in the case of power to signal cables or signal to signal cables, it may not be. One area where these effects might have a power system effect is when the system is powering sensitive electronic equipment.

So good references on the subject are:

Noise Reduction Techniques in Electronic Systems, 2nd Ed," Henry W. Ott,
John Wiley & Son, 1988 ISBN: 0-471-85068-3

"IEEE 518 - Guide for the Installation of Electrical Equipment to Minimize
Electrical Noise to Controllers from External Sources," IEEE, 1982
ISBN: 0-471-89359-5

"Grounding and Shielding Techniques In Instrumentation, 3rd Ed," Ralph
Morrison, Wiley Interscience,1986
ISBN: 0-471-83805-5

"Grounding For The Control Of EMI," Hugh W. Denny, Don White Consultants,
Inc., Gainesville, VA.

"Grounding and Shielding In Facilities," Ralph Morrison & Warren H. Lewis,
Wiley Interscience, 1990
ISBN: 0-471-83807-1

Bill Mostia
=====================
William(Bill) L. Mostia, Jr. P.E.
Partner
exida.com
Worldwide Excellence in Dependable Automation
[email protected](b) [email protected](h)
www.exida.com 281-334-3169
These opinions are my own and are offered on the basis of Caveat Emptor.

 

As a rule, different voltages should not be running in the same conduit. However;

Two voltages may be run in the same conduit provided the lower voltage wiring has sufficient voltage insulation rating to meet the rating of the higher voltage conductors.

Also it is required that the different voltage conductors be running to the same piece of equipment.