Breaker with 90? terminations
- Thread starter augie47
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I don't think I ever installed a breaker with more than 3 digits...:lol: Even if the breaker was rated 90C at the terminals the equipment would also need to be rated 90C
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I tried searching but got nowhere. The best thing to do is to call the manufacturers and see if one is available. My point before was that the breakers may have 90C lugs but that isn't helpful since the equipment is not rated 90C. I
I have not checked but I understand that some equipment do have 90C lugs but the unit itself is only 75C
I have not checked but I understand that some equipment do have 90C lugs but the unit itself is only 75C
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
This lug, for instance is rated 90C -- that is what the 9 means in the CU9AL
Interesting leading question not knowing the rest of the story. Are you implying that you want to use 90, degC rated wire and apply it at 90degC? Even so you must keep one thing in mind that the beaker/device has tested and listed for use with and applied with wire rated at ampacity of 75degC unless otherwise allowed uy the application information.
As such, what is you point?
The only breakers that I know of where 90degC rated wire must be used are 100% rated breakers. When applied according to their instructions in order to achieve their you also must use 90degC rated wire BUT the wire is to be applied at 75degC.
As such, what is you point?
The only breakers that I know of where 90degC rated wire must be used are 100% rated breakers. When applied according to their instructions in order to achieve their you also must use 90degC rated wire BUT the wire is to be applied at 75degC.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Remember it is the termination not the lug.
Most molded case breakers are listed to UL489, which pretty much prevents them from having terminations which allow conductors to be sized based on the 90C insulation.
Power circuit breakers, like those in drawout switchgear, are listed under different standards and rarely have terminations made directly to the breaker itself. This 'lug landing pad type' of construction is almost always available for use with conductors sized based on 90C.
Enclosure design also impacts the termination rating.
Most molded case breakers are listed to UL489, which pretty much prevents them from having terminations which allow conductors to be sized based on the 90C insulation.
Power circuit breakers, like those in drawout switchgear, are listed under different standards and rarely have terminations made directly to the breaker itself. This 'lug landing pad type' of construction is almost always available for use with conductors sized based on 90C.
Enclosure design also impacts the termination rating.
Would the question now be is this a molded case beaker which to my knowledge 2500a is the largest or a power breaker?
The question was somewhat generic. A fellow inspector has a job where the conductors would have to be figured at their 90? rating to be large enough. I can't recall the exact size but the range was 2000-3000. We were discussing options and I thought I recalled a breaker that could be employed in that situation'
In hindsight I think A 100% breaker is what was on my mind.
In hindsight I think A 100% breaker is what was on my mind.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Don't forget the enclosure.
I don't believe UL Listed switchboards have terminations for 90C sized conductors, unlike ANSI switchgear which commonly has them.
Are you referring to a 100% rated breaker?
If I remember correctly when the UL489 breaker is listed for application to 100% rating yes the enclosure must be suitable for application at 100% in addition to the wire be rated 90degC but applied per 75degC.
Also, I agree that ANSI gear is applied by a different set of rules.
That is correct. But continuous loads do not have to be factored at 125%. That could amount to better than the factored value at 90?C ampacity for an all or nearly all continuous load.
You are correct when I overlooked adding that note. When sizing the wire it is based upon not 100%+125% as you would with a common 80% rated breaker but 100%+100% which gives one an opportunity to optimize the wire size thus the requirement for 90degC rated wire. Actually, an 80% breaker is no different that a 100% breaker excerpt for the addition of a heat rize test which allows it to be UL listed for a 100% application.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Even if the terminations were 90deg, I've never seen a breaker in an enclosure that was tested / listed for 90 degree termination ampacity, even ANSI type.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
What is voltage?
I no expert in the over 600 volt equipment but think there may be some chance of seeing 90C terminal ratings there.
I am not aware of anything in 600 and below that is 90C though.
I no expert in the over 600 volt equipment but think there may be some chance of seeing 90C terminal ratings there.
I am not aware of anything in 600 and below that is 90C though.
kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
MV equipment is rated for 90 degree C. But the cable is also rated for 90 and 105 deg C; i.e. MV90 and MV105 cable. Most MV cable manufacturers have quit making MV90 because its easier to just make one type. Although the ampacity is still listed in the NEC. It is applied in the same manner as the same 75 and 90 degree cable, code wise.
You will not find 90 degree rated low voltage equipment, I have discussed this topic with manufacturers and it is too costly for them, and there really is no reason to do it; i.e. no market.
You will not find 90 degree rated low voltage equipment, I have discussed this topic with manufacturers and it is too costly for them, and there really is no reason to do it; i.e. no market.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
I think that a stand-alone enclosed hang-it-on-the-wall 100% rated breaker will often have 90C rated terminations, usually Cu only. But... you STILL would have to size the cables for the 75C rating. I can't think of any scenario in which you can SIZE the cables going into any breaker using the 90C column, regardless of the rating of the terminations etc.
Sometimes I wonder if the 90C column should even exist, except as an exception with the rules spelled out as to the ONLY times those ratings can be used. This issue seems to cause more confusion than it's worth.
Agree. I have found for those not trained in the Code (and some that are) it can be one of the most "misapplied" sections
big john
Senior Member
- Location
- Portland, ME
It was already proposed, but the CMP rejected the idea.
EDIT: Nevermind, I see the proposal also would've removed the ability to use the 90? for derating which is no bueno.
However, I still don't understand the CMPs response that someone might actually need to termination at 90? rated equipment.
Last edited:
- Status