Systems being designed at MV-105 capacity is not an attesting of compliance. It can just as easily be the opposite.
As to ambient + rise, you're the one making the 105°C-rated terminations permitted claim without substantiation, so you tell us...
Conductor Ampacities
- Thread starter LLTEI
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As to ambient + rise, you're the one making the 105°C-rated terminations permitted claim without substantiation, so you tell us...
Looked at a mv system today
all 105 cables used at rated ampacity
Nexus rep was there, mv 90 cables will be gone in 3 years or so
they were all terminated
go figure
inspected by local, 3rd party and state agencies
compliant and placed in service
Hmmmmm
Credibility? On the internet?
Lol
people actually seek self worth and validation lol
nutso ain't it
Can you imagine people actually having emotional involvement?
weird
this has so little to do with 'real life' that it is unfathomable
bigger issues
last night during my power sys II final I get a text that my wife was at e room with a possible heart attack
kept her overnight, just sprung her
she's fit as a fiddle
stress test bp/rate was 130/80 and took 9 minutes to 165 pulse
stress related, especially crazy tax season, coupled with her ms took a toll
she's got to learn to say f&$k it when approriate
which is most of the time lol
Still questionable. In the MV portion of the industry, many go about design and implementation without full regard to NEC compliance. They think MV is no different than utility work.
The NEC places an MV 90°C-rated termination temperature limit unless otherwise identified (UOI). All you have to do is show us the UOI. Mere speculation doesn't count one iota towards that end.
Good thing you have no authorative say in the matter
no they don't, they allow 105 cable and teminations
it's reality, it's being done every day around the world
but I get it
they are all wrong and you are correct
gotcha
I'm not saying they or you for that matter are wrong. All I'm saying is you are not showing anything to substantiate your claim that it is compliant... and that is all I am asking for.
FWIW, there is no change to the wording of 110.40 on the table for 2017 NEC approval.
The reality proves it
all mfgs make 105 cables
all are ul and nec compliant
the nec allows use at rated ampacity and above (up-rated based on ambient)
they are all terminated
there is no need for change
'shall be permitted' NOT 'shall be'
and 'unless otherwise identified'
your interpretation is the ampacity of the 105 is limited to that of the 90
then why don't they say that?
why show the 105's higher ampacity if it is limited to the 90's by the termination?
why even make 105 cables if the ampacity is limited to 90, ie, can't be utilized?
because that is not the case
It seems you are not differentiating between conductor ampacity, to which adjustment and correction factors apply, and minimum conductor size due to termination temperature limitations of 110.40, which is based on the 90°C ampacity rating of the conductor.
it is you who mistakingly thinks 110.40 limits ampacity
The conductor is not rated 90, but 105
meaning that at rated ampacity it runs 105
and does not have to be derated or limited to the equivilent 90
if so why make it?
wwhitney
Senior Member
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I just realized that 110.14(C) is a general requirement for all voltages, not just 0-600V. So 110.40 uses the "shall be permitted" language for 90C termination ampacities to provide relief from the base temperature for terminations ampacities of 60C or 75C specified in 110.14(C).
Are these 105C MV equipment terminations not "listed and identified" for 105C? If they are, then 110.14(C) permits using 105C ampacities for the termination. So what are you guys arguing about?
Cheers, Wayne
iirc 110.40 is for > 600
There are a couple questions
is it code compliant to terminate a 105 cable with a 90 termination?
the cable is operated per nec at 80% of its rating (cable ampacity = 1.25 x load)
yes
are there terminations rated 105?
yes
will the cable when run at 80% reach 105
no
probably not even 90
I see this as a spirited discussion with big egos involved lol
There are a couple questions
is it code compliant to terminate a 105 cable with a 90 termination?
the cable is operated per nec at 80% of its rating (cable ampacity = 1.25 x load)
yes
are there terminations rated 105?
yes
will the cable when run at 80% reach 105
no
probably not even 90
I see this as a spirited discussion with big egos involved lol
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- Connecticut
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The NEC does not require that cable be operated at 80% of its rating.
The part you are missing is what the equipment itself is rated. In LV equipment, you can find terminals rated 90°C, but the equipment as a whole unit is only listed for 75°C operation. Thus, the minimum conductor size is based on the conductor ampacity equivalent at 75°C, even when using e.g. 90°C-rated wire.
The same concept applies to over 600/1000V equipment, but the minimum conductor size is based on the 90°C ampacity equivalent in the appropriate Table... UOI equipment is used.
Just trying to get you (or me) sorted out on this matter. Spirited discussion, yes... but no super ego to bruise here. :happyno:
- Location
- Connecticut
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- Engineer
FIFY
It wasn't broken :?
I know, but some think the 80% is automatic in LV requirements, though it is actually the converse of 125% factoring for continuous loads. No such 125% continuous factoring requirement for MV.
Not sure if I am the one who missed it lol
The mv SW without question is rated for use with 105 cable
105 cable does not de-rated to use it
>600 v feeder
if only xfmrs sum of rated i
very seldom loaded to 100%
xfmr + util equip
xfmr i sum + 125% balance
if no xfmr 125% of load
If supervised location under engineering supervision
most cases I would guess
most apply the 125% (I do)
if next size is a std, use it
if not, and close, downsize to std size
judgement call based on duty cycle, etc
but in the overall scope using ~125% as a rule of thumb costs little
if only xfmrs sum of rated i
very seldom loaded to 100%
xfmr + util equip
xfmr i sum + 125% balance
if no xfmr 125% of load
If supervised location under engineering supervision
most cases I would guess
most apply the 125% (I do)
if next size is a std, use it
if not, and close, downsize to std size
judgement call based on duty cycle, etc
but in the overall scope using ~125% as a rule of thumb costs little
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