Using 90°c wire at 90°c ampacity

[Coppersmith]

If such 90c pressure connector or enclosures exist listed at 600 V or less, then here is Hell frozen over as promised.

They do exist as mentioned in post #1.

 

[packersparky]

Yes, this is precisely what I described.

Bonus question: 110.14(C)(2) seems to be about feeders exclusively. What if we are not talking about a feeder? What if we are talking about branch wiring going to utilization equipment? Does the 75 to 90 degree transition still have to be in a separate box on either side?

IMO it cannot be used for a branch circuit.

 

[ramsy]

IMO it cannot be used for a branch circuit.

See 210.19(A)(1) Exception

However, no such animal is seen listed for 600 V or less.

 

[Coppersmith]

See 210.19(A)(1) Exception

However, no such animal is seen listed for 600 V or less.

That section only says the wire has to be of the proper ampacity. No argument there.

Not sure which animal you are referring to: utilization equipment, wire, connector or something else.

90°c wire exists, 90°c connectors exist, boxes to put them in exist, 90°c raceway exists, and utilization equipment is moot since we are not connecting to it at 90°c.

 

[ramsy]

..90°c wire exists, 90°c connectors exist, boxes to put them in exist, 90°c raceway exists, and utilization equipment is moot since we are not connecting to it at 90°c.

The NRTL Certification for 90°c operation of terminal or Polaris blocks --in separate enclosures-- should satisfy the AHJ's and claims adjusters.

Polaris blocks may exist for 90°c operation, but the NRTL listing is usually medium voltage and more expensive, not 600 V or less.

 

[Coppersmith]

The NRTL Certification for 90°c operation of terminal or Polaris blocks --in separate enclosures-- should satisfy the AHJ's and claims adjusters.

Polaris blocks may exist for 90°c operation, but the NRTL listing is usually medium voltage and more expensive, not 600 V or less.

copied from Polaris's website:

POLARIS™Pre-Insulated ConnectorsMulti-Conductor Connector, One Side Wire EntryIPL SeriesSPECIFICATIONS• UL Listed 486B Wire Connector (Dry location).• Temperature Rating/Voltage: AL9CU.Cold temperature rated to -45 °C, rated 600V, 90 °C.• Wire Type: Dual rated for use with copper and/or aluminum cables.Not for fine-stranded, flexible wire.• Torque Chart: See page 34.

 

[ramsy]

Here is the Polaris Installation Guide that shows 600 V dual-rated Cu/Al @ 90c, except for "tt 600 SERIESAREAL7CUAND75 C"

This Guide is not the actual product listing certification from UL.
Did the NRTL / UL classification require testing 90c at continuous use?

When encountering 90c claims at 600 V or less, product certification from NRTL's may show its not continuous use.

What prevents insurance adjusters from looking up Polaris product listings, and using that to prove your negligence?

 

[don_resqcapt19]

Here is the Polaris Installation Guide that shows 600 V dual-rated Cu/Al @ 90c, except for "tt 600 SERIESAREAL7CUAND75 C"

This Guide is not the actual product listing certification from UL.
Did the NRTL / UL classification require testing 90c at continuous use?

When encountering 90c claims at 600 V or less, product certification from NRTL's may show its not continuous use.

What prevents insurance adjusters from looking up Polaris product listings, and using that to prove your negligence?

Almost all termination or splice points are listed for use at 90°C. The equipment that they are installed on is typically not so listed and the equipment itself, and not the terminating lug is the limiting factor. Where the termination or splice point is not part of the equipment, they can be used at 90°C
From the UL Guide for "Wire Connectors and Soldering Lubs (ZMVV)

Ampacity level rating:

A. Equipment use — Equipment wiring requirements may restrict the sizing, ampacity and temperature ratings of connected conductors. Equipment requirements may limit 90°C or higher-rated conductors to 60 or 75°C ampacity in accordance with Electrical Equipment for Use in Ordinary Locations (AALZ).​

B. General use — Connectors rated 75°C are intended for use at ampacities not greater than those for 75°C-rated conductors, and connectors rated 90°C are for use at ampacities not greater than those for 90°C-rated conductors. Connectors may be marked with "75C" or "90C" to represent these levels. Alternatively, these rating levels may be represented by a 7 or 9 associated with the marking "CU," "AL" or "AL-CU," e.g., "AL9," "AL9CU," "AL7CU," "CU7," "CU9." Connectors not marked with an ampacity number 7 or 9 have an assumed level per the following table. Use of higher-temperature-rated conductors is not prohibited, provided the ampacity levels continue to be based on the 75 or 90°C ratings.​

​

 

[ramsy]

UL uses numbers on each product's UL label to check for valid listings, and the testing standards passed.

Unfortunately, as is often the case, the Polaris Install Guide shows an invalid UL label, with no numbers. See upper left corner.

97% of fake, counterfeit, or field installed UL labels originate from Chinese counterfeiters, neither valid nor provided by UL. This one was easy to spot, with no numbers on the label.

 

[ramsy]

Almost all termination or splice points are listed for use at 90°C. The equipment that they are installed on is typically not.. From the UL Guide for "Wire Connectors and Soldering Lubs (ZMVV)

Thank you for the listing info. Did not realize 90°C lug listings are typically found with 600 V or less ratings.

I see outside insulation on those Polaris lugs may limit voltage, but don't see 600 V insulation holding up to a continuous 90°C. A valid NRTL label pointing to a test standard would certainly help settle that question.

 

[electrofelon]

Thank you for the listing info. Did not realize 90°C lug listings are typically found with 600 V or less ratings.

I see outside insulation on those Polaris lugs may limit voltage, but don't see 600 V insulation holding up to a continuous 90°C. A valid NRTL label pointing to a test standard would certainly help settle that question.

If they say 90 degree, then they can take it - I dont think they would be rated for 90 degrees if they couldnt :?: Practically all conductors are rated 90 degrees. Most wire nuts are even rated 105 degrees.

 

[ramsy]

Here is a Polaris OEM flyer showing "AL9CU" for lug ratings that match Don's description of the UL catagory (ZMVV)

For me, this settles the OEM's intention for use of its 600 V lug insulation with 90°C ampacity.

Inspecting the packaging for a valid UL label with proper file number reference, and examining the UL 486B test standard, may help clarify how it handles 90°C.

 

[Carultch]

If I am reading the specs correctly, Polaris connectors are rated at 90°c. If I am running 90°c wire between two panels with 75°c terminals and I terminate the wire in Polaris connectors and then run a short length of larger wire sized at 75°c ampacity to the panel terminals, can I use the 90°c column on the ampacity chart to size the wire? This might save some money on larger wire sizes.

In theory, you can do this, as long as you are terminating in separate enclosures from the 75C rated equipment. In practice, the only reason I'd see to do it, would be if you are salvaging an error. Maybe it could be a value engineering decision, but I don't see that working in practice. What you'd save in wire size for the majority length, you'd spend in the tap blocks, separate enclosures, and extra complexity. And if it is a serious enough length, voltage drop management will also become an issue.

 

[Coppersmith]

In theory, you can do this, as long as you are terminating in separate enclosures from the 75C rated equipment. In practice, the only reason I'd see to do it, would be if you are salvaging an error. Maybe it could be a value engineering decision, but I don't see that working in practice. What you'd save in wire size for the majority length, you'd spend in the tap blocks, separate enclosures, and extra complexity. And if it is a serious enough length, voltage drop management will also become an issue.

There are no errors here. On my current project the panel is several hundred feet from four new utilization equipment units. The wire is already upsized for voltage drop reasons. Boxes are already installed both at the panel and at the utilization equipment to allow space to downsize the wire to fit the terminals on the breakers and the equipment. Polaris connectors are already being used to transition the wire sizes. The wire is already XHHW-2 which is good for 90°c. All of this money has already been spent and all this complexity was required and has already been put into the system.

Unfortunately it did not occur to me to use the 90°c wire at it's 90°c ampacity until after I built the system and ordered the wire. If I had designed it that way I could have used smaller wire and used smaller conduit which would have SAVED money. Note that voltage drop has already been accounted for.

 

[winnie]

Unfortunately it did not occur to me to use the 90°c wire at it's 90°c ampacity until after I built the system and ordered the wire. If I had designed it that way I could have used smaller wire and used smaller conduit which would have SAVED money. Note that voltage drop has already been accounted for.

If you had designed the system using 75C ratings, and then _upsized_ that wire for voltage drop, then you are already using the conductors at less than the 75C ampacity. So for design (voltage drop) reasons you are already not able to use the 90C amapcity.

Only if the run were short (not much voltage drop) or you could tolerate lots of voltage drop would using the 90C ratings allow you to save money.

-Jon

 

[Coppersmith]

If you had designed the system using 75C ratings, and then _upsized_ that wire for voltage drop, then you are already using the conductors at less than the 75C ampacity. So for design (voltage drop) reasons you are already not able to use the 90C amapcity.

Only if the run were short (not much voltage drop) or you could tolerate lots of voltage drop would using the 90C ratings allow you to save money.

I might be confused, but I think if I designed the system for 90°c ampacity and then upsized the wire for VD, it would probably end up being at least one size smaller than if I started at 75°c.

 

[wwhitney]

I might be confused, but I think if I designed the system for 90°c ampacity and then upsized the wire for VD, it would probably end up being at least one size smaller than if I started at 75°c.

No, it would be the same. Voltage drop does not depend on insulation temperature.

You calculate the smallest wire allowable based on insulation temperature, and the smallest wire that keeps you under your voltage drop limit. Then you use the bigger of the two sizes for your wire. So if voltage drop controls for 75C insulation temperature, it would certainly control for 90C insulation temperature.

Cheers, Wayne

 

[Coppersmith]

No, it would be the same. Voltage drop does not depend on insulation temperature.

You calculate the smallest wire allowable based on insulation temperature, and the smallest wire that keeps you under your voltage drop limit. Then you use the bigger of the two sizes for your wire. So if voltage drop controls for 75C insulation temperature, it would certainly control for 90C insulation temperature.

Ok, I definitely was/am confused.

I looked up the VD formula and I ran some calculations manually. The formula does not contain a variable for insulation temperature as stated above and in previous posts. And on a long run of wire, once you determine the size wire needed it already has a higher ampacity than even the 90°c column allows so the insulation temperature column is moot and more importantly the insulation temperature cannot be used to reduce the wire size. My apologies if I seemed stubborn in this discussion.

==================================

300 foot run
42 amps needed (without VD #8CU is 55 amps at 90°c, #8AL is 45 amps)
208 volts at 3% max VD = 6.24v

VD = 2 x K x I x D / CM

For 1/0 AL (ampacity at 75°c = 120 amps, ampacity at 90°c = 135 amps)
VD = 2 x 21.2 x 42 x 300 / 105600 = 5.059v

For #1 AL (ampacity at 75°c = 100 amps, ampacity at 90°c = 115 amps)
VD = 2 x 21.2 x 42 x 300 / 83690 = 6.38v

 

[winnie]

Okay, I think I see now.

There are 2 different ways of looking at this, by looking at wire ampacity first or by looking at voltage drop first.

There could be situations where if you pick the wire based on the 90C ampacity, and then calculate voltage drop, and increase size from the 90C ampacity requirements, you will end up with a conductor that is still smaller than that sized using the 75C ampacity. This situation will be found only for extremely large conductors, eg. if you need a single conductor with 500A ampacity then with 90C insulation you need 700kcmil, but with 75C insulation you need 900kcmil.

Or you could look at voltage drop first. As you note, most calculations don't take into account temperature (and when calculations do include temperature, the voltage drop gets _worse_ as conductor temperature increases). To get a particular voltage drop for a given current and circuit length, you need so many circular mils of conductor cross section. It doesn't matter what the insulation temperature rating is, since voltage drop depends on the conductor only.

-Jon

 

[kwired]

Well, what if they had the building heat on? Then I would be saving them money.

Depends on details. Did energy lost from those conductors transfer to space that is desired to have heat or was it lost to outside the space needing heat? Did that lost energy from the conductors cost more or less than the heat from the conventional heating system?

In theory, you can do this, as long as you are terminating in separate enclosures from the 75C rated equipment. In practice, the only reason I'd see to do it, would be if you are salvaging an error. Maybe it could be a value engineering decision, but I don't see that working in practice. What you'd save in wire size for the majority length, you'd spend in the tap blocks, separate enclosures, and extra complexity. And if it is a serious enough length, voltage drop management will also become an issue.

:thumbsup:


VD is dependent on conductor resistance, which changes with cross sectional area as well as temperature. Something I don't think was brought up yet is that if the conductor is operating at 90C it should have higher resistance than same conductor at 75C and insulation won't change a thing. 75C insulation just deteriorates more rapidly than 90C insulation at this temperature but won't change current carrying ability of the conductor itself.