Square D Mag Gard FHP interrupting rating

[philly]

Does anyone happen to know what the interrupting rating is for a Square D Mag Gard FHP Motor Circuit Protector (MCP) breaker? From looking at the Mag Gard FHL breaker which has an interrupting rating of 25kA I would venture to guess that the FHP breaker had the same rating since the only difference with the P vs the L refers to the mechanical connection of the breaker?

These FHP breaker are being used as part of combination starters located in a Square D Model 6 MCC. The Short Circuit Rating on the front of the MCC said that it was rated for 42kAIC, however these FHP breakers may only be rated for 25kA. Would the overall rating of the MCC then be 25kAIC since these FHP breakers are only rated for 25kA?

What is an MCC does not have any information on the front in regards to the short cirucit rating? Do you simply have to go off of the lowest rated breaker installed in the MCC?

 

[jim dungar]

Does anyone happen to know what the interrupting rating is for a Square D Mag Gard FHP Motor Circuit Protector (MCP) breaker? From looking at the Mag Gard FHL breaker which has an interrupting rating of 25kA I would venture to guess that the FHP breaker had the same rating since the only difference with the P vs the L refers to the mechanical connection of the breaker?

These FHP breaker are being used as part of combination starters located in a Square D Model 6 MCC. The Short Circuit Rating on the front of the MCC said that it was rated for 42kAIC, however these FHP breakers may only be rated for 25kA. Would the overall rating of the MCC then be 25kAIC since these FHP breakers are only rated for 25kA?

What is an MCC does not have any information on the front in regards to the short cirucit rating? Do you simply have to go off of the lowest rated breaker installed in the MCC?

The third letter in the part number deals with the mounting of the device "L" means lugs on the line side and "P" means bus mounting pad.

A Mag-Gard breaker must be used as part of a listed assembly, therefore you should be looking at the 'series-combination' rating of the MCC starter bucket.
Many people that perform a 'device evaluation' as part of an arc flash analysis incorrectly pass judgement only on the breaker's AIC rather than the bucket's SCCR. They mis the facct that the starter (contactor and overload block) also has an SCCR.

UL Listing requires that every MCC bucket have an SCCR label in it.

Yes, an MCC's overall SCCR is limited to that of the lowest SCCR of any device installed in it.

 

[philly]

The third letter in the part number deals with the mounting of the device "L" means lugs on the line side and "P" means bus mounting pad.

A Mag-Gard breaker must be used as part of a listed assembly, therefore you should be looking at the 'series-combination' rating of the MCC starter bucket.
Many people that perform a 'device evaluation' as part of an arc flash analysis incorrectly pass judgement only on the breaker's AIC rather than the bucket's SCCR. They mis the facct that the starter (contactor and overload block) also has an SCCR.

UL Listing requires that every MCC bucket have an SCCR label in it.

Yes, an MCC's overall SCCR is limited to that of the lowest SCCR of any device installed in it.

Thanks

I'm trying to determine an "equpment evaluation" for an MCC that has several of these FHP breakers in the MCC. These breakers have an interrupting rating of 25kA and are subjected to a fault duty of 38kA and therefore fail the device/equpiment evaluation. The Nameplate of this MCC however lists a short circuit rating of 42kA.

So would this MCC have an overall rating of 42kA or would it have to be 25kA since this is the lowest rated protective device installed in the MCC. The MCC has a main breaker so maybe its possible that these breaekrs are series rated. Thes FHP breakers are Motor Circuit Protectors (MCP's)

I've seen some MCC's say on their namplate however that the equipment rating is based off of the lowest rated protective device installed in the equipment up to a maximum rating.

 

[Jraef]

Thanks

I'm trying to determine an "equpment evaluation" for an MCC that has several of these FHP breakers in the MCC. These breakers have an interrupting rating of 25kA and are subjected to a fault duty of 38kA and therefore fail the device/equpiment evaluation. The Nameplate of this MCC however lists a short circuit rating of 42kA.

So would this MCC have an overall rating of 42kA or would it have to be 25kA since this is the lowest rated protective device installed in the MCC. The MCC has a main breaker so maybe its possible that these breaekrs are series rated. Thes FHP breakers are Motor Circuit Protectors (MCP's)

I've seen some MCC's say on their namplate however that the equipment rating is based off of the lowest rated protective device installed in the equipment up to a maximum rating.

You didn't read Jim's response thoroughly. What he said is correct, it does not natter what the breaker rating says, it only matters what the ENTIRE STARTER ASSEMBLY is rated for as a tested and listed unit. It's often the case that the sum of the parts does not appear to equal the whole. But you must remember that on a mag-only breaker, it has NO OTHER ACCEPTABLE USE other than as part of a listed tested assembly. So if in the listing and testing of that assembly, the mfr chooses the test it at a higher level than the rating of one component, that's up to them. If it passes, it passes, end of story.

The "dirty little insider secret" on that though is that most of the time, there is no physical difference between a breaker listed at 35kAIC and it's brother listed at 65 kAIC, other than the label and the price. It's actually too expensive to manufacture parallel products like that, so they only make one that will pass at the higher level, but they label it for the lower in order to have a reason to get a higher price whenever they can. You will have a hard time getting any of them to admit it openly, but that is the truth. So when Sq D went to list that bucket at 42kAIC even though the breaker said 35, they knew before they started that it was going to pass.

 

[jim dungar]

Thanks

I'm trying to determine an "equpment evaluation" for an MCC that has several of these FHP breakers in the MCC. These breakers have an interrupting rating of 25kA and are subjected to a fault duty of 38kA and therefore fail the device/equpiment evaluation. The Nameplate of this MCC however lists a short circuit rating of 42kA.

You need to know the SCCR of the starter bucket (it is too bad that this info is skipped by most arc flash data collectors).
Have you checked with Schneider Electric using the serial number of the MCC?

from their website:
One of their Electrical Shortz publication on UL845
http://static.schneider-electric.us... Voltage Motor Control Centers/8998DB0802.pdf
"The short-circuit-current rating of an MCC motor-starter unit may be higher than the interrupting rating of the circuit breaker in the unit. For example, some of our Listed starter units that have short-circuit-current ratings of 65 kA or 100 kA at 480 V contain an FH thermal-magnetic circuit breaker, which has an interrupting rating of 25 kA at 480 V. The explanation for this is that when combination motor controllers are tested under the requirements of UL 845 and UL 508 it is the entire package (that is, the entire combination controller) that is tested and rated, not the individual components."