# inspector wont allow vfd cable



## VELOCI3 (Aug 15, 2019)

https://www.wireandcableyourway.com/uploads/file/29505%20Technical%20Data%20Sheet%20(English).pdf




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## tmessner (Apr 1, 2013)

Thanks: I will pass it by the ahj. I am concerned that it does not have a SO rating.


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## oldsparky52 (Feb 25, 2020)

tmessner said:


> Thanks: I will pass it by the ahj. I am concerned that it does not have a SO rating.


What is an "SO" rating?


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## VELOCI3 (Aug 15, 2019)

Severe outdoor I believe. It’s a more robust SJ type cable

Edit:
S= Service
O=oil resistance
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## Wardenclyffe (Jan 11, 2019)

*SO Cord* or *SO Cable* is a name often used for a power *cord* or portable *cord*. The name comes from the UL letter designations used on power *cords*. ... For example, Type *SO* portable *cord* is a 600-volt service *cord* with an oil resistant outer jacket. 



Why is it called so cord? - Google Search


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## VELOCI3 (Aug 15, 2019)

chainflex® servo cable CF27.D




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## Cow (Jan 16, 2008)

We've ran quite a bit of VFD cable, including the Belden type linked above, but I have never been asked for a cord end/recep.

I would not expect VFD cable which is typically TC-ER rated, including the Belden VFD cable, to be used with a cord end, so I would agree with your inspector.

Maybe Jraef, Micromind, or one the others will see this post and will be able to tell you what they've seen or used in the past.

I'd also lean pretty hard on the supply house to reach out to their various wire vendors to see what they can come up with.

You can't be the only one that's ran into this issue, you just have to find the right person to know what the solution is. 

What would make your life considerably easier, is too know if the customer really needs shielded wire and/or a cord end/recep?

If you can do away with either of those two options, your job will be get considerably more straight forward and be able to utilize readily available materials.


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## tmessner (Apr 1, 2013)

Okay


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## gpop (May 14, 2018)

tmessner said:


> Everybody involved except the person that writes the specs agree that vfd is not needed here. He is a master electrician hired by my customer to be a class action jerk. Sorry about that. He is supposed to over see these dairy barn projects and he writes the specs. Arguing with him is not an option. It will be shielded and it will have an attachment plug for easy replacement. I think they keep a spare motor on hand with a short cord for rapid change out. A few more examples: We use Meltric DSN plugs and stuff, disconnect rated. We are required to use a stainless steel knife switch ahead of the DSN recep. Rotary switches are not allowed, We must use stainless steel disconnects in the same area where switchgear is installed all nema 1 painted steel. The good part is that the bills are not questioned and are paid promptly and we do a lot of work for them.



Its not all that surprising as the equipment is probably being sold with a service contract. Rather than troubleshoot on site which require a skilled person they simply make it plug and play (or at least switch it to see if the problem goes away). They also tend to consider any problem they have ever en counted and spec it into the next job.


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## tmessner (Apr 1, 2013)

gpop said:


> They also tend to consider any problem they have ever encountered and spec it into the next job.


That is a lot of the problem.


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## Jlarson (Jun 28, 2009)

Would he be ok with a type G cable, I mean that's SO cords big brother. You can get shielded type G, we've used that before on portable VFD gigs.


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## JRaef (Mar 23, 2009)

I have used the Belden shielded flexible motor cable linked above and got away with it, *but at times, I have not* and here is why. 

Yes it is outdoor rated, sunlight oil and water resistant, basically the same as any PVC jacketed portable cord. But technically, it is "TCER" cable, TC meaning *Tray Cable*, and although it can be used in tray or conduit or even direct burial, it is NOT the same as SO cord. The S in SO is for "Service" rated which adds the requirement for abrasion and damage resistance, meaning you are going to be dragging in around in the parking lot or across a gravel road where people will drive over it, hence the EPR (rubber) outer jacket. That Belden cable is called "motor cable" because you (presumably) would not be doing that with a motor. But as TC cable it needs to be "supported and protected", so if your machines just have it laying on the ground, i*t is not approved for that use*. If however your Meltric plugs just have a short piece of it going into a cable tray, it's fine. So it depends on how you are using it.

What I now use for those "lay it on the ground" applications is Shielded SOOW cord, it's available from most of the major players, just not in stock in most places, and I have not seen it above #10.






SOOW Cable | Allied Wire & Cable


SOOW is a service cable that is oil, weather, and water-resistant. This cord resists abrasion, gaining, oil, ozone, solvents, and water.




www.awcwire.com





And just as a reminder, on POWER shielded cables, you must ground BOTH ends of the shields, not just one like on shielded comms cables. That them implies that you have ground available at the motor end. Be careful about that.


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## micromind (Aug 11, 2007)

Jlarson said:


> Would he be ok with a type G cable, I mean that's SO cords big brother. You can get shielded type G, we've used that before on portable VFD gigs.


I've used type G shielded too. It's incredibly tough but not as flexible as other types. 

Type G will have 3 conductors the same size. The ground might be the same size or it might be smaller or it might be several smaller ones. Type G-GC is the same as type G except it'll have smaller grounds and one smaller yellow wire for the ground check that MSHA requires. Useless if you're using a plug on the end........

#6 type G will likely have all 4 conductors the same size.


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## paulengr (Oct 8, 2017)

First off a load reactor is silly. On the load side the big issue is reflected wave and you are nowhere near enough cable for that. What the load reactor does for you is to convert 3-5% of the output power into heat that you are pouring all over your VFD. If you were at a line length where you need it, the dv/dt filter does far better for the same money with less than 1% output power converted into heat. If you are under 50 feet it does nothing for you. It might be useful on the line side if you have a possible transient or short circuit issue.

Second what you are looking for is a borderline VFD cable that is flexible cord. This means mining cables.

Look at NEMA WC-58. These are all mining cables so they are all portable cords. Several are shielded. Amercable and Telefonika are two manufacturers. Now there are two issues. The first is that it’s not UL. Fortunately most are tested by CSA so they are Listed. Second is NEC doesn’t list all of them in the portable cord list. Still they are often used for deep well submersible cables, cranes, various marine equipment, and of course mining and excavating equipment.

VFD cable itself is 100% total scam. It’s just grossly overpriced 2 kV cable. The claims by the manufacturers are so ludicrous it’s actually funny. See this article although I probably need to update it a bit. My opinion hasn’t changed.



https://www.linkedin.com/pulse/vfd-cable-snake-oil-paul-campbell


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## tmessner (Apr 1, 2013)

After talking to my lead man on the job, we are going to use standard 6/4 soow cord. The leads are less than 10' and we have a reactor behind the drive. These motors are in a separate building from all of the rfid readers and other sensitive items. Thanks for all of the help. I will let you know if things go south for us.


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## tmessner (Apr 1, 2013)

Paul: I totally agree with you. My Werner sales people agree.


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## paulengr (Oct 8, 2017)

tmessner said:


> Paul: I totally agree with you. My Werner sales people agree. We are dealing with an arrogant know-it-all that knows everything. (Just ask him) Unfortunately he is the one who signs off on the project.


So have him find you an acceptable cable and give him the NEC list of portable cable types. You can’t comply with something that doesn’t exist.

And on those mining cables I used to deal directly with Amercable because I was often buying a few thousand feet at a time. So I could get discounts on say 350 MCM 8 kV SHD-GC that weighs about 10 pounds per foot and costs $50/foot at factory direct discounts! MPF isn’t that bad but not shielded or NEC. That cable runs draglines with 70 yard buckets (2 car garage) with roughly 8-12 MW peak power draw every dig cycle. Dragging SHD-GC by hand is hard work.

A certain VFD manufacturer (Allen Bradley) heavily promotes VFD cable. A couple years ago a port loading facility had severe fluting and reflected wave issues. Fluting was so bad it was eating bearings out of the gear boxes too. The motors were hundreds of feet from the VFDs. So of course Allen Bradley sold them on replacing those thousands of feet of cable with VFD cable. When it did NOTHING AB claimed they terminated it wrong. After installing dv/dt filters on all their VFDs and grounding brushes and insulating bearings on the motors with fluting problems, suddenly we weren’t selling them new motors or rewinds every other week.

Now if you are into selling blood pressure medication I printed out the page from the Allen Bradley manual that stated in plain English that they should have used dv/dt filters, NOT VFD cable. The site manager was pretty red in the face. I thought about showing him my drive prices but I’m not into rubbing salt in fresh wounds.


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## Cow (Jan 16, 2008)

tmessner said:


> After talking to my lead man on the job, we are going to use standard 6/4 soow cord. The leads are less than 10' and we have a reactor behind the drive. These motors are in a separate building from all of the rfid readers and other sensitive items. Thanks for all of the help. I will let you know if things go south for us.


Do you put RFI filters on the vfd's?


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## tmessner (Apr 1, 2013)

Not on this job. We have on others where we have had noise issues.


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## JRaef (Mar 23, 2009)

Even 10’ of unshielded cable on the output will allow a lot of RF noise to bleed out of the cables like a radio antenna, possibly affecting other control systems in the area in ways you may not notice immediately. I don’t recommend doing that.


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## Quickservice (Apr 23, 2020)

Cow said:


> We've ran quite a bit of VFD cable, including the Belden type linked above, but I have never been asked for a cord end/recep.
> 
> I would not expect VFD cable which is typically TC-ER rated, including the Belden VFD cable, to be used with a cord end, so I would agree with your inspector.
> 
> ...


I learned to call Houston Wire & Cable with any kind of technical questions like this. They have never failed to give me the correct answer... usually right off the top of their heads.


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