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#81236 07/29/02 09:45 AM
Joined: Jul 2002
Posts: 6
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3 Way Offline OP
Junior Member
First, I admit to being a PE who went thru college with no NEC training and learned enough to handle a few exam questions. There is so much to learn about the code I wanted to tap your experience. Here's a couple questions.

Q1> For equipment connections >100amps, is it permissible to use 90C ampacity wire (adjusted for derates) so long as equipment lugs are rated 90C?
NEC 2002 Re 110.14.c.1.b.2

Q2> Is it permissible to use type DLO cable (90C Diesel Locomotive cable ... re Houston Wire and Cable) in a conduit raceway provided equipment lugs are rated 90C? Further, DLO is not shown in 310.16 ... does this mean it should never be used?

Appreciate your thoughts ... 3 Way

2017 / 2014 NEC & Related Books and Study Guides
#81237 07/29/02 10:18 AM
Joined: Jul 2002
Posts: 38
E
Member
Q1: In order to use the 90C ampacity ratings, every connection must be rated at 90C, that means any splices and terminations. I'm not an expert, but I'm not aware of any equipment that has 90C rated terminations.

#81238 07/29/02 12:27 PM
Joined: Nov 2000
Posts: 2,148
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You can use 90°C wire anywhere you want as long as you use it at a current rating equal to or lower then the current rating for the same size conductor based on the temperature rating of the terminal and equipment. For example 3/0 at 90°C has an ampacity of 225 amps. You can use this wire with 200 amps of load on 75°C rated equipment and at 165 amps for 60°C rated equipment. If you have 6 current carrying conductors in the raceway, you can derate from the the 90°C rating. Remember that both the equipment and terminals must be rated at 90°C to use the full 90°C rating.
As far as the DLO cable, I often use it for large DC motors that have 700 volt armatures. DLO is rated at 1000 or 2000 volts depending on the type, and it sure makes it easier to make the connections in the motor junction box. The last DC motor that I hooked up had 8 535.3kcmil DLO cables for the positive lead and 8 more for the negitive lead. I guess that its use in this type of application is a code violation, but I don't see any hazards created by its use.
Don


Don(resqcapt19)
#81239 07/29/02 10:18 PM
Joined: Apr 2002
Posts: 2,527
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Moderator
You may want to see: https://www.electrical-contractor.net/ubb/Forum2/HTML/000606.html

About Q2—

Some DLO has an NEC "RHH/RHW-2" rating, but it must be so identified for use as building wiring. Ask Houston if theirs is appropriately listed on the cable jacket.

For the sake of other readers, DLO flexibility comes from individual rope-lay 24AWG strands. http://www.amercable.com/DLOInst.asp [Compare that to 37-strand 500kcmil THHN}

#81240 07/30/02 08:26 AM
Joined: Jul 2002
Posts: 6
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3 Way Offline OP
Junior Member
Bjarney -- thanks for the Amercable link; their product looks good.

Will also follow-up w/ Houston and Anixter about jacket markings, although I don't recall either showing RHH or RHW-2 nor do I remember either rated CT for tray use.

I'm still a bit confused on using 90C wire on 75C lugs. DLO cables list ampacitiy for 90C @ 30C ambient. Any way to derate for use w/ 75C lugs? For instance, 4/0 is rated 405 amps! What would same 4/0 be rated @ 75C?

3-Way

#81241 07/30/02 10:36 PM
Joined: Dec 2001
Posts: 440
Likes: 1
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3 way,
Don is correct, but let me throw it at you from a different direction. The lowest temperature rating of the equipment, lugs, splices, wire, etc. is the limiting factor. 75 degree lugs will limit 90 degree wire to the 75 degree column in 310.16. So, if you buy a disconnect with 75 degree lugs, you can use 90 degree wire, but you can't exceed the ampacity ratings from the 75 degree column of Table 310.16. As far as derating for temperature, or number of conductors in a conduit is concerned, if you use 90 degree wire, start your calculation with the number in the 90 degree column. Work your calculation, and check it to make sure that it will carry the load, and meets or exceeds the 75 degree column, and you are good to go.
Hope it helps. I'll stay away from the DLO question for now.

Regards,
Doc
HMEL 688


The Watt Doctor
Altura Cogen
Channelview, TX
#81242 07/31/02 08:06 AM
Joined: Nov 2000
Posts: 2,148
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3 Way,
The 405 rating is the 90°C ampacity of 4/0 copper in open air. Look at Table 310.17. If you are using it in a raceway you need to use Table 310.16 and if in cable tray you need to look at the rules in 392.11(B).
Don


Don(resqcapt19)
#81243 07/31/02 11:59 AM
Joined: Jul 2002
Posts: 6
3
3 Way Offline OP
Junior Member
Good feedback...

I contacted Amercable to request catalog and info re DLO ampacity @ 75C. They have a conversion chart for different temps and gladly mailed a copy.

i'm involved with industrial motors, switchgear, MCC's, etc. We use cable tray extensively and RGS where required. i've never allowed DLO in trays (the Houston variety w/ Hypalon jacket) since it wasn't so rated. However, Amercable uses a different jacket that is tray rated. i'm inclined to try theirs using appropriate temp derates. much of our gear has the option for 90C lugs (for extra cash of course). our electricians sure like DLO's flexibility and smaller diameter vs THHN, etc. they say it's easier to pull in conduit.

Oh, another advantage of Amercable vs Houston, is the RHH / RHW-2 label on the jacket.

does anyone know if 90C lugs are an option for service entrance equipment? ever seen such?

Thx, 3-Way

#81244 08/20/02 05:08 PM
Joined: Mar 2001
Posts: 345
T
Member
3 Way Wrote:
Quote
does anyone know if 90C lugs are an option for service entrance equipment? ever seen such?

We got some as a special order from Square D years ago for some power equipment in a desert environement. The engineers were trying to compensate for the extremely high ambient temperatures inside photo voltaic powered communications equipment shelters.
--
Tom


Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
#81245 08/20/02 07:35 PM
Joined: Apr 2002
Posts: 2,527
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Moderator
"...advantage of Amercable vs Houston, is the RHH / RHW-2 label on the jacket."

Please be advised such NEC ratings for DLO are by no means exclusuve to either firm.

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