Parallel equipment grounding conductor

[don_resqcapt19]

This is not new. My library goes back to 1996. It is in there.

But if one does not do heavy feeds, outside, cold weather - conduit is likely more cost effective. So, it is probably not something you have been around much. Not majik - just not stoneage.

ice

It has nothing to do with having used the product or if the product it used in that manner. Show me a document that says the MC cable that uses wires as part of the equipment grounding conductor is suitable for use in parallel installations. Remember that when the rule for a full size EGC in parallel circuits was first put into the code, it only applied to raceways. Cables were included at a later date.

You also mentioned something about "Where conductors are installed in parallel in multiple raceways or cables" suggesting that maybe you were using GFP on the circuit as was in the code prior to the 2008 code. There was a provision that said you could do that if you had a GFP device that was listed for protecting the equipment grounding conductors. There has never been a device so listed and those provisions are no longer in the NEC.

 

[kenaslan]

I must also disagree with ice, I find no info that allows paralleling of type MC-HL cable in any of my books, Southwire, General Cable, or Okonite. I have placed a call to my Okonite engineering rep for clarification, and will post later. I have used these cables extensively in the mining industry and have always used a full size ground. I think ice is confusing Canadian code with the NEC. Paralleling of the ground wire when using Teck90 cable is completely allowed in Canada. However here in the USA it is not. Also using a combination of both the metal sheath and internal EGC would not be a ?full size? EGC as it is a COMBINATION of the two. The product data sheet of CLX cable lists the grounding size of the cable. You may use this value and nothing else.

 

[iceworm]

What applies to one does not necessarily apply to the other.

There is nothing in 250.122(F) that says that. In fact that section says "...Where conductors are installed in parallel in multiple raceways or cables ..."

Conduit is not cable. That is why they are spelled different. You are only looking at one code section. And there is no argument that both conduits and cables must have an EGC sized per 250.122.F

As for the code treating cables and conduits different , I point out that 250.118.10.c definitly treats conduit and cables different.

ice

 

[iceworm]

... Show me a document that says the MC cable that uses wires as part of the equipment grounding conductor is suitable for use in parallel installations. ...

You have already asked that and I have already answered. However, you have not yet answered:

Can't say I have either. Never knew I needed one. The code is permissive. Do you have a document that says "no". Paralleled installation is not listed in 330.12.

ice

 

[iceworm]

... You also mentioned something about "Where conductors are installed in parallel in multiple raceways or cables" suggesting that maybe you were using GFP on the circuit as was in the code prior to the 2008 code. There was a provision that said you could do that if you had a GFP device that was listed for protecting the equipment grounding conductors. There has never been a device so listed and those provisions are no longer in the NEC.

Although I am a pretty good engineer, I have never been able to use devices that don't exist.

ice

 

[kenaslan]

I must also disagree with ice, I find no info that allows paralleling of type MC-HL cable in any of my books, Southwire, General Cable, or Okonite.

I ment to say paralling of the EGC. Yes you can parallel MC-HL but not the EGC. Full size means full size. Without a full size ground you have an unsafe installation.

 

[iceworm]

... I think ice is confusing Canadian code with the NEC. ...

Well, you blindsided me with this comment. I did not see this comming. I'm unsure how to answer. Is this meant to be arrogant and demeaning? Or do you seriously think I have an open copy of the NEC sitting next to an open copy of the CEC (if that is the right name) on my desk?

The latter is so ludicrous, I strongly suspect the former. However, just in case:

No, I don't have a copy of the Canadian Electric Code anywhere in my office. No, I have never had any opportunity to read or study the CEC.

Given these, it is highly un-likely that I would have sufficient knowledge to possibly allow confusion on this subject.

Yep, that's me, just color me "dumb as a post" concerning the CEC.

ice

 

[iceworm]

... I have placed a call to my Okonite engineering rep for clarification, and will post later. ....

Excellent idea. I talked to George (with Okonite - not a rep) in Portland. Just curious, who are you dealing with? I will be very surprised if Okonite comes back with, "No, you can't parallel CLX. The grounding conductor is too small. The sheath can not be used as a grounding conductor." If they do, I will have a lot of work to do - starting with a call to Okonite asking for a letter clarifying their position on paralleling CLX.

One reminder, Okonite does not publish all of the necessary data in the CLX Product Data sheet. One must also read their CLX Cable Handbook.

... I have used these cables extensively in the mining industry and have always used a full size ground. ...

Perhaps you are confusing MC-HL with with Type G or Type W. Both of which are quite common in the mining industry (so I have read - never worked in the mining industry) I use both G and W for temporary services (construction). As I'm sure you already know:

G has a grounding conductor, but it is not always big enough for parallel installations.

Type W, does not have a grounding conductor. One generally orders 4c, using the fourth as a full size grounding conductor.​

I.... The product data sheet of CLX cable lists the grounding size of the cable. You may use this value and nothing else.

And you deny that 250.110.10.c says something quite different? Why is that?

ice

 

[iceworm]

I... Yes you can parallel MC-HL but not the EGC. Full size means full size. Without a full size ground you have an unsafe installation.

I don't follow you on that one.

1. What exactly is unsafe about using the sheath of CLX for the grounding conductor?

2. What exactly is unsafe about using the parallel combination of the sheath and internal grounding conductors as the EGC?​

One thing (among many others - truth, Don's creditability is high) I give Don credit for is he is not attacking the safety or physics behind using the parallel combination of the sheath and internal grounds. He arguments are strictly a legal issue.

ice

 

[kenaslan]

OK. I have the correct answer. Ice, it would help if you quoted the correct code. Also try not being so snitty. Rudeness will get you nowhere.

250.118(10)b is the correct answer.
I also have the Okonite table for anyone interested. I cannot upload the "CLX Sheath as a Ground Conductor pdf", as it exceeds the forum size limits. I can email it to anyone interested in this info.

250.118(10) Type MC cable that provides an effective ground-fault current path in accordance with one or more of the following:
a. It contains an insulated or uninsulated equipment grounding conductor in compliance with 250.118(1)
b. The combined metallic sheath and uninsulated equipment grounding/bonding conductor of interlocked metal tape?type MC cable that is listed and identified as an equipment grounding conductor
c. The metallic sheath or the combined metallic sheath and equipment grounding conductors of the smooth or corrugated tube-type MC cable that is listed and identified as an equipment grounding conductor


I cannot upload the CLX Sheath as a Ground Conductor pdf. as it exceeds the forum size limits. I can email it to anyone interested in this info.

 

[iceworm]

... Ice, it would help if you quoted the correct code. ...
250.118(10)b is the correct answer. ...

CLX Type MC (XHHW) product data sheet, page 3-1:

Sheath: Close fitting, impervious, continuous, corrugated aluminum C-L-X per UL1569​

Assuming you are using NEC 2011, I'm pretty sure that meets 250.118.10.c not b. "b" is interlocked armor. Right now I'm thinking I did quote the right section.

And I'm certain you are using the 2011 cause 10C was not in the 2008.

ice

 

[iceworm]

... Also try not being so snitty. Rudeness will get you nowhere. ....

ken -
Prior to stamping my forehead with the R I suggest you read what you wrote. Your premiss that I can not tell if I am reading the CEC vs the NEC is pretty demeaning.

However, as I said, if your intent was not demeaning, then the second half of my response applies. I don't own nor have never read any of the CEC. Therefore, I am certain I am not confusing the two. This is not rude, it is a dead serious response to a near ludicrous comment.

I will translate your current comment as you had no intent to be demeaning. Okay, I'll let it go - I promise, no more from me on this.

ice

 

[don_resqcapt19]

Conduit is not cable. That is why they are spelled different. You are only looking at one code section. And there is no argument that both conduits and cables must have an EGC sized per 250.122.F

As for the code treating cables and conduits different , I point out that 250.118.10.c definitly treats conduit and cables different.

ice

My comments have only been about using the MC cable in parallel applications where the EGC in each cable must be full sized per 250.122(F). I don't see anything that tells me that the EGC in the 500 kcmill MC cable is suitable for use in 800 amp circuits.

 

[iceworm]

OK. I have the correct answer. ...
250.118(10)b is the correct answer. ....

I'm not following you completely. 250.118.10.b (or "c" as the case may be) is the answer to what? I'm serious. I'm not sure just which question you are answering.

ice

 

[kwired]

Although I am a pretty good engineer, I have never been able to use devices that don't exist.

ice

Using devices that don't exist changes your title to "inventor"

 

[don_resqcapt19]

...I also have the Okonite table for anyone interested. I cannot upload the "CLX Sheath as a Ground Conductor pdf", as it exceeds the forum size limits. I can email it to anyone interested in this info.

...

Can you post a link to that document?

 

[don_resqcapt19]

Although I am a pretty good engineer, I have never been able to use devices that don't exist.

ice

When the rule that said you could use GFP to protect a smaller than required EGC in parallel circuits first came out, the code was not completely clear that you need to to have a GFP that was listed for the protection of EGCs, and standard GFP equipment was being used.

 

[iceworm]

My comments have only been about using the MC cable in parallel applications where the EGC in each cable must be full sized per 250.122(F). ...

Yes. I got that. And I got it that you only are considering the internal grounding conductors as the cable EGC. I'm pretty sure I am clear on what you are advocating. I've been trying to read all of the posts carefully.

... I don't see anything that tells me that the EGC in the 500 kcmill MC cable is suitable for use in 800 amp circuits.

Yes. Got that as well. It follows from the above statement.

My translation is you do not interpret 250.118.10.c as defining the EGC for paralleled MC-HL cables. I got that.

So, give me a grade on how I am doing at paying attention to your position. :happyyes: or :happysad:

ice

 

[iceworm]

When the rule that said you could use GFP to protect a smaller than required EGC in parallel circuits first came out, the code was not completely clear that you need to to have a GFP that was listed for the protection of EGCs, and standard GFP equipment was being used.

Yes this is an interesting subject. There is nothing new about setting protective relays to trip inside of equipment damage curves. It is commonly done for transformers, cables (or conductors), motors, generators - and likely lots of other stuff I don't deal with. Generally speaking, coordination is not about protecting the end use equpment. Coordination is about protecting the conductors, distribution equipment, structures, and sometimes even people.

There was no stretch to pick a suitable protective relay and set it to trip inside of the equipment grounding conductor damage curve. This concept works well for bigger stuff - and, of course, any parallel circuit could easily be considered bigger stuff.

Why the code panel decided that particular protective device (EGC) needed a special mention about listing has always baffled me.

As to why no one ever built and listed one is not because the technology was not there, it is because the market was not there. JMO

ice

 

[don_resqcapt19]

...Why the code panel decided that particular protective device (EGC) needed a special mention about listing has always baffled me.

As to why no one ever built and listed one is not because the technology was not there, it is because the market was not there. JMO

ice

I agree with both of the above. The correct settings on the GFP would protect the EGC.