even more 110.14(C) question

[hardworkingstiff]

In previous threads I have asked about using type W cable at marinas and we've discussed how even though Table 400.5(B) allows for a higher ampacity than 310.16, 110.14(C) limits you to 310.16 due to temperature limitations (unless equipment is listed otherwise).

At the power center, we often will loop feed a couple/three power centers on one feeder. One particular power center we use has a copper buss bar and studs for our terminations. We use a UL listed lug on the type W cable (and a listed crimp). These lugs are bolted to the buss bar back to back.

Let's use the example of a 1/0 W cable on a 120/240-volt feeder. Using 400.5(B) at 75C we have an ampacity rating of 207-amps (I think). Let's say we are loop feeding a power center that has (2) 50-amp receptacles and dead-ending at a 2nd power center that has (2) 50-amp receptacles. The cable has an adequate ampacity but 110.14(C) does not allow it (at least that is the consensus from previous threads) because it limits the terminations to 310.16 ampacities.

Here is an argument I'm thinking about making and I'm asking for feedback.

The 1st power center has the lugs bolted back to back. This type of connection is an approved connection (i.e. motors). Since all the current that goes to the 2nd power center will pass from the feed in lug to the feed out lug (yes, while they are both bolted to the buss bar), the buss bar will actually not see/feel the current that is just passing through. Therefore, the buss bar will only ever see/feel the current that is being used by that particular power center and not anything that is being used by the 2nd power center. Can we then say that the "termination" at the 1st power center is only 100-amps and not 200-amps?

 

[augie47]

Lou, Am I reading into the question that you are wanting to use the higher (200 amp) temperature termination rating at that point ?
If so, IMO, yes.

 

[jwelectric]

Would 400.8 come into play here?

 

[hardworkingstiff]

Lou, Am I reading into the question that you are wanting to use the higher (200 amp) temperature termination rating at that point ?
If so, IMO, yes.

Yea, I just can't get past the 75C rated W cable not being allowed to be used at 400.5(B) rating because of termination issues. Looking to understand and have possible alternate methods of interpretation that the local AHJ would agree with. They are a stubborn bunch at times (like I'm not :roll. :grin:

 

[hardworkingstiff]

Would 400.8 come into play here?

Not sure exactly what you're getting at, 8but for my application:

400.8 1st sentence says "Unless specifically permitted in 400.7 ...."

400.7(10) Where specifically permitted elsewhere in the Code.

555.13(2) specifically allows using Portable Power Cables for wiring of marinas.

I hope this addresses what I think you are alluding to.

 

[augie47]

Lou,
I don't know if this helps but there is a pictorial (which, unfortunately I have not yest located) that showed a 75?C termination run to a junction and connected to a 90? rated cable at both ends thus allowing one to use the 90? rating where the cable did not terminate on 75? equipment.
If your cable terminates on a terminal strip which has a 75? or 90?
terminals I would think you can use the appropriate cable ratings.
Perhaps someone else has that pictorial handy.

 

[hardworkingstiff]

Lou,
I don't know if this helps but there is a pictorial (which, unfortunately I have not yest located) that showed a 75?C termination run to a junction and connected to a 90? rated cable at both ends thus allowing one to use the 90? rating where the cable did not terminate on 75? equipment.
If your cable terminates on a terminal strip which has a 75? or 90?
terminals I would think you can use the appropriate cable ratings.
Perhaps someone else has that pictorial handy.

Thanks Augie, I know and have the drawing (SQ D I believe).

The pedestal manufacturer has stated their buss bar is rated for the W ampacities of 400.5(B), but the local AHJ is requiring the UL listing for this specifically.

On future jobs we (the Engineer and I) have no problem in up-sizing the cable size, but we have a stopped job (engineered using 400.5(B) ampacities) that needs a new permit and the customer has purchased all the material that we are going to have difficulties with if/when it gets going again. I'm trying to get my ducks in a row for when this happens.

 

[Smart $]

Lou,
I don't know if this helps but there is a pictorial (which, unfortunately I have not yest located) that showed a 75?C termination run to a junction and connected to a 90? rated cable at both ends thus allowing one to use the 90? rating where the cable did not terminate on 75? equipment.
If your cable terminates on a terminal strip which has a 75? or 90?
terminals I would think you can use the appropriate cable ratings.
Perhaps someone else has that pictorial handy.

Thanks Augie, I know and have the drawing (SQ D I believe).

The pedestal manufacturer has stated their buss bar is rated for the W ampacities of 400.5(B), but the local AHJ is requiring the UL listing for this specifically.

On future jobs we (the Engineer and I) have no problem in up-sizing the cable size, but we have a stopped job (engineered using 400.5(B) ampacities) that needs a new permit and the customer has purchased all the material that we are going to have difficulties with if/when it gets going again. I'm trying to get my ducks in a row for when this happens.

The first question I have before going down this road (hmmm... getting a deja vu sensation here just now... so that would be again???) is: What is the terminal temp rating at the supply end of the "W" cable? To use higher than 310.16 75? ampacities, the terminations?and equipment?at both ends must be rated at least 90?... and even then it doesn't get you out of using 310.16.... you just get to use the 90? column.

 

[hardworkingstiff]

The first question I have before going down this road (hmmm... getting a deja vu sensation here just now... so that would be again???) is: What is the terminal temp rating at the supply end of the "W" cable? To use higher than 310.16 75? ampacities, the terminations?and equipment?at both ends must be rated at least 90?... and even then it doesn't get you out of using 310.16.... you just get to use the 90? column.

Yea, I don't want to see that "condition of use" thing get going again.

The supply end will be changed to a THHW conductor rated at 200-amps per the 75c column of 310.16 prior to the breaker. This option is not readily available at the power center end of the cable.

 

[Smart $]

Yea, I don't want to see that "condition of use" thing get going again.

The supply end will be changed to a THHW conductor rated at 200-amps per the 75c column of 310.16 prior to the breaker. This option is not readily available at the power center end of the cable.

As I see it, there are two clauses (empasized below) which allow you to use other than Table 310.16 ampacities.

• 110.14(C)(1) general, in part states, "Unless the equipment is listed and marked otherwise, conductor ampacities used in determining equipment termination provisions shall be based on Table 310.16 as appropriately modified by 310.15(B)(6)."
• 110.14(C)(1)(b)(2) states, "Conductors with higher temperature ratings, provided the ampacity of such conductors does not exceed the 75?C (167?F) ampacity of the conductor size used, or up to their ampacity if the equipment is listed and identified for use with such conductors "

If (and that's a big IF) your equipment—the power centers—is listed, marked, and/or identified for use with Type W cable/conductors, there is no problem using Table 450.5(B) for the coordinated conductor ampacity.

EDIT: If you are using Type W 75?C rated cable, the 110.14(C)(1)(b)(2) clause would be rendered moot.

 

[hardworkingstiff]

This is the letter the manufacturer sent. I deleted the manufacturers name for political reasons.

In regards to the ampacity of our incoming conductor buss terminations (manufacturer's name here) pedestals are designed and tested per UL231 standards for Power Outlet Pedestals, as such the pedestals have been temperature tested at the maximum rated ampacity, 250A, at the terminations. This rating will suffice for the type of 75 Deg. C conductors listed in NEC Table 400.5 (B)

They have printed labels you get from an office supply with their name, no address nor phone number nor UL symbol for me to install on the terminal block. These labels say it's OK to use the ampacities on Table 400.5(B) of the NEC. The customer has already purchased all of the pedestals and wire, so that's why they are sending me the labels. I probably could have printed a better looking label on my laser printer.

I'm just looking for a plan B if the AHJ is not convinced (which the AHJ has stated) that the manufacturer understands the issue. It may be OK when it comes time to do this, but I'm a bit anal on this and would like to have another angle to come from if I need to. So I was just looking at the angle that although 2 conductors are bolted to the buss bar, the actual termination only sees the 100-amps being used by the 1st power center (because the lugs are bolted back to back and the pass through amperage never sees the buss bar) and the 1/0 rating in table 310.16 is 150-amps at 75c so we are good to go.

 

[Smart $]

...

I'm just looking for a plan B if the AHJ is not convinced (which the AHJ has stated) that the manufacturer understands the issue. It may be OK when it comes time to do this, but I'm a bit anal on this and would like to have another angle to come from if I need to. So I was just looking at the angle that although 2 conductors are bolted to the buss bar, the actual termination only sees the 100-amps being used by the 1st power center (because the lugs are bolted back to back and the pass through amperage never sees the buss bar) and the 1/0 rating in table 310.16 is 150-amps at 75c so we are good to go.

I understand your reasoning, but it has the wrong premise. Yes, current plays a role in termination limitations, but it is the heat generated by the current which has direct influence. The current is an indirect influence. It only becomes direct when you also consider size and material of the conductor (i.e. copper or aluminum, typically).

IMO, the labels you mention should suffice, if installed as you say, under the manufacturer's support and direction (though it won't help much in a liability suit if you have to state you got the labels at your local office supply ).

There's only one way out.

 

[hardworkingstiff]

I understand your reasoning, but it has the wrong premise. Yes, current plays a role in termination limitations, but it is the heat generated by the current which has direct influence. The current is an indirect influence. It only becomes direct when you also consider size and material of the conductor (i.e. copper or aluminum, typically).

I was hoping no one would say this <sigh>.

IMO, the labels you mention should suffice, if installed as you say, under the manufacturer's support and direction (though it won't help much in a liability suit if you have to state you got the labels at your local office supply ).

They really did come from the manufacturer.

There's only one way out.

I love that song, and I have been in that situation in 1974, stuck upstairs, ..... but that's another story not for this forum. :grin:.

 

[jwelectric]

Not sure exactly what you're getting at, 8but for my application:

400.8 1st sentence says "Unless specifically permitted in 400.7 ...."

400.7(10) Where specifically permitted elsewhere in the Code.

555.13(2) specifically allows using Portable Power Cables for wiring of marinas.

I hope this addresses what I think you are alluding to.

Wasn't looking anything up and working from my head so thank you for clearing this up.

 

[220wire]

I ran into this situation before. My questions are: Could you derate the load any to help with the needed amapcity? Are you able to use the ampacities of the manufacturer or the NEC?

RV peds are similar too in regards to looping them. I wonder how they compare