Question about what wires to use

I'm doing a project that requires me to send some ac signals from one plc to another that is about 70' away. My intentions was to run one Beldon cable (20conductors/22gauge) and use it for all my signals to the other plc.

Is there any reason not to use this Beldon cable for ac signals?

Note: the Beldon cable will be inside a 1" pvc conduit along with separate wires for dc current. Also the Beldon will NOT be used for both ac and dc.

Thanks, Dave

the Idea of both Ac and CD signals in the same cable is not a real problem.
So long as the voltage is not above 50 V.
For Safety - Relays are used to interface higher voltages.
the risk of Isolating one Panel and still having a live supply in that panel is dangerous

fishenguy,

I'm sorry, but that is not allowed. conductors that remain energized in a control panel after the main disconnect is turned off must be Orange - NFPA 79 13.2.4.1 2007 edition.
there are also wiring requirements that must be met.

Depending on you application, you may also be required to have interfacing relays.

again, depending on your application, the conductors can be run in RNC conduit, not pvc.

You must also have placards on the control panels indicating dual sources of power.

regards,
james

beldon is a brand not a type of cable not enough info to answer your question though

Hello Dave,

Let me start with my first recommendation: Have you considered networking the PLCs and messaging the necessary information between processors instead of cross connecting them with IO? That is the way I would go first, if you can.

I also recommend you get a copy of NFPA 79 Electrical Standard for Industrial Machinery. James mentioned some of the relevant issues - there are several. NFPA79 spells out that Orange (Not Yellow, although lots of people think that is the right color) is to be used for cross system wiring that remains energized, but it makes some exceptions for cables provided you adhere to some specific requirements spelled out in the code. The standard isn't meant to hog tie you. Look at as a guide to help you build quality systems. The handbook is about 40 bucks online and well worth it.

22AWG wire is smaller than what I prefer to use, but it is allowed. The circuit providing power cannot be fused at more than 3 amps. Pay heed to the 3 amp limit - that does not mean you can fuse an IO module at 8 amps just because its rated for 8 and use 22AWG wire just because the PLC module on the other end only draws 150mA on its inputs. You are limited to 3 amps because that is what the wire is rated to carry. All too often I've seen IO modules fused based on what the card is rated at, not what the smaller capacity wire can carry.

My personal preference is to not use anything smaller than #18 unless its OEM wiring already permanently attached to a device by the manufacturer, even for DC discrete and analog signals. (#18 is 7 amps BTW, so the #18 circuit cannot be fed by any breaker/fuse larger than that, no matter what kind of devices may be in the circuit)

The cable must also have insulation rated high enough for the highest voltage it will share a conduit, raceway, or enclosure with. So for example if it shares a wire duct with 480V conductors, even if it just crosses thru the duct, you have to have at least 600V rated insulation. Some of the instrumentation cables have insulation rated at 300V and some is even lower so check before ordering. Also, the insulation rating is the peak to peak voltage so if the cable shares an enclosure with 120VAC then it has to have a 300V rating, 150 isn't going to cut it.

Since you are running a conduit, without knowing more, I would recommend that you pull #18 orange wires - if that works for you.

Orange? Dad blast it, I just got through pulling two yellow wires 120' through 6 j-boxes to connect a signal between two panels.

I guess I need to break down and pay for one of those handbooks too...I am one of those guys who has learned "hand-me-down style" about electrical codes from the old timers...I did go to a seminar for two hours back in '99 but that was more of a "how to use the NEC book" class that I never put to good use.

Since we no longer have an EE I am expected to perform as one, so I need to demand some money be spent on training before I fudge up something more important than insulation color.

OkiePC said:

Orange? Dad blast it, I just got through pulling two yellow wires 120' through 6 j-boxes to connect a signal between two panels.

I guess I need to break down and pay for one of those handbooks too...I am one of those guys who has learned "hand-me-down style" about electrical codes from the old timers...I did go to a seminar for two hours back in '99 but that was more of a "how to use the NEC book" class that I never put to good use.

Since we no longer have an EE I am expected to perform as one, so I need to demand some money be spent on training before I fudge up something more important than insulation color.

Click to expand...

Yes Okie Orange is the "new" yellow. I want to say it was changed 2 years ago(can't be more than 3)so don't feel to bad. Getting the book Alaric mentioned is a good idea. It reads about as well as the NEC so you should have hours of enjoyment with it...

With the NFPA 79 on your desk people will atleast assume you know what you are doing.

I allways buy the handbok to the NEC code book, cause it has pictures. but wait doesent it only have to be orange in one panel? maybe he could put a j-box in the middle just to muddle up things. LOL
Alaric,all kidding aside id go with the com's thing., Steve

The 2007 version says Orange. I don't have the 2012 yet, but just
asked for one to be ordered.

It is my understanding that yellow was deprecated because of the IEC.

yes I saw that it was about $65 now seems the 2007 has deprecaited wonder what color it will be this year? oh and what about UL 508a wouldn't want it to feel left out.
Best regards ,Steve

It is yellow through the whole run from a leased equipment spare output on a Modicon Quantum PLC through their existing circuit breaker to a relay in an interface panel in the attic. The equipment support engineer asked me to remove the exisitng wire that was long ago abandoned on the machine (in another room) and he asked me to tape it and flag it with red tape. We only have ornage brown yellow and black tape, so I used yellow tape and tucked it into the raceway and put all the covers back on the panduit and left it much better than I found it. The panel has a large rectangular wireway above it with long panels. on the front. I took 5 screws out to remove them, and installed about 40 that I had to scrounge for to put it back right...all with a nutdriver...

There are no terminal blocks to switch colors, although that is my preference and probably a requirement. I can easily go back and add blocks though I routed the wire across a din rail just for that reason. Also, I used a white wire for the remote neutral, and labelled it with a reference to the panel with the Modicon. This is probably another violation, but I didn't have any 14awg or smaller wire that wasn't red black or white...

Boy, I was right with you Okie. It was yellow last time I looked, I guess it is time to read it from cover to cover again...

well let me splain..... it like politics.... the wire compay lobies the nec board_
ie: kick back to add. change colors to increse wire sales ect..... same thing happened to crayons.....LOL

Alaric said:

The 2007 version says Orange. I don't have the 2012 yet, but just
asked for one to be ordered.

It is my understanding that yellow was deprecated because of the IEC.

Click to expand...

LOL... I didn't realize it had been that long...where have the years gone.