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In other words if we twist things a bit we can make it look like you did not misstate things.
Din Rail Mount Breakers
- Thread starter Dennis Alwon
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In other words if we twist things a bit we can make it look like you did not misstate things.
mbrooke
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In other words if we twist things a bit we can make it look like you did not misstate things.
Ok, maybe I could have been more explicit on that one, but my point is UL489-molded case breaker testing has no 80% requirements.
mbrooke
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Ok, correct me if I am wrong, but the white book appears to be going by the NEC rather then advocating the NEC go an 80% route for continuous loads?
I believe ANSI got involved in there somewhere, too.
IIRC, the statement is made as a recommendation.
This is what I understand what you question of the device is.
Be aware of the difference of the common UL489 and the UL10-77 listed supplimentary protector type OCPDs.
Supplementary protectors are used to provide overcurrent protection where branch protection (for example, UL 489 MCCB or MCB) is already provided or not required. The units can be installed as a component within, or as a part of an appliance or a piece of electrical equipment.
Supplementary protectors are ideal replacements for fuses that are applied as a supplementary protector (in addition to branch protection if required)
They are quite often 35mm DIN-rail mountable, utilizing spring clips
These are standard protectors, recognized by UL and CSA under UL 1077 and CSA 22.2
They are CE marked in accordance with Low Voltage Directive CE LVD 2006/95/EC.
Supplimentary protectors are also commonly available with different trip curve choice options unlike the UL489 !isted devices which can provide better protection and / coordinatoin. But it must be emphisized the UL1077 does not replace the necessarily use of the UL489 listed devices as required be the NEC.
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All true, however the breakers in that link are UL489 listed.
Many, if not most of the DIN rail mounted breaker mfrs are offering a UL489 listed version now, mostly because people were misusing the UL1077 breakers and getting red tagged once the inspectors were educated.
But there are still issues with using them, especially at 480V, i.e. they are only slash rated, the AIC is lower than many people realize, and these somewhat misleading marketing statements about them being "100% rated".
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Agreed. That why it is important to understand what the differences of UL489 andUL1077 devices are, where the use of UL1077 devices are allowed by the NEC what a 100% rated device is and how it is tyo be allplied, etc.
With " 80%" and "100%" rated OCPDs it is often misuderstood that a 100% tasted OCPD is superior to an 80% tasted OCPD. They are not. In order foir a 100% tasted device to be listed as such it must go through addition tests to allow it to graduate to the honor of getting a badge of the UL listing for a 100% application.
What that amounts to to being able to for go the conductors must be sized to carry 125% of the continuous current + 100% of the noncontinuous current rule the the OCPD rating is sizes to protect the wire the OCPD is then actually applied at 80% of its rating. Thus, you magically now have an "80% rated breaker." When a breaker has been tested using 100%+100% it can pemit you to use a smaller conductor depending upon what the computed load ends up to be. In order to do so that wire must be 90degC rated wire not 75degC but the rating must still be per the 75degC column. In doing so you can save money by using a smaller wire since 90degC rated wire is commonly used anyway.
The trade off is that the wire must be protected by a listed 100% rated OCPD which is more expensive and that the 100% rated OCPD MUST BE installed per the installation strictly per its instructions. The advantages really only apply withe larger conductor/breakers where the cost savings of using a smaller conductor is beneficial.
With smaller breakers it is very impractical.
So it is a matter is understanding what 100% is referring to, is it how they are UL489 tested as one of the previous post pointed out or how the wire is sized, 125%+100% or 100%, and the breaker applied, at 80% or 100%.
It is about the wire.
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So back to my original question of why does dim rail breakers have the 100% rating and others are not marked that way. I assume it has something to do with PV but I don't know if that is true or why it is so.
As one of the others posted the commonly N UL489 breaker is as lso tested and tasted as t 100% BUT it is how the breaker can be applied.
The so caslled "100% rated breaker" that you are referring to how do you sized the conductors that it is supposed to be protecting? Do you size therm accordong to the NEC, 125% of the continuous load + 100% of the non continuous load, the wire must be rated to carry that laod. Then do you size the breaker to protect the wire? If so where does that 100% that you are talking about come into play?.
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I understand that but again- why is one marked and not the other if they are both rated 100% continuous. Regardless of whether or not the end result may be the same I figured there may be some reason why the dim rail breaker has the 100% rating mentioned.
Sure the wire must be rated to carry the load but if everything is rated 100% continuous then you could load the breaker to 100% even for continuous loads. No??? Not sure if the dim rails are rated 100% or not. I guess I was thinking there was a reason for the dim rail breakers being marked as such. Maybe it is just the different manufacturers using that as a sales gimmick
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One difference that might be a factor is that DIN rail breakers to not have stabs to a common bus that shares the heat load. Instead they have individual input and output wires that carry off the heat.
The heat loss from the side of the breaker case, as blocked by the breaker immediately adjacent to it, would be similar for breaker panel versus DIN rail, so this would not be as big a factor.
The heat loss from the side of the breaker case, as blocked by the breaker immediately adjacent to it, would be similar for breaker panel versus DIN rail, so this would not be as big a factor.
I undersdtand wehere you asre comming from should the commn UL489 breasker be marked as suitasble for 80% continuous of its rating but the HFD3150 thast I'm holding in my hand has no marking as such. Yes, that 100% marking may be a marketing gimmick. But are the other breakers applied in the same way
I do find it interesting that this question hasn't been posed directly to the manufacturer. What the significance of this mark. And if a 15a DIN rail mounted and the common load center mounted breaker are applied in the same way or what in fact is the advantage of the breaker marked 100%.
You may getting out in the weeds on this as there are no marking on breakers installed in load centers nor on the enclosure. It is back in the fact of how the we are is sized and that breakers as re sized to protect the wire.
Does the NEC recognized the application of a DIN rail mounted breaker differently?
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