Fault currents motor contribution

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xptpcrewx said:
Sections 110.9 or 110.10 do not require "calculations", they simply require that equipment/devices are properly applied. Calculations are one method to demonstrate compliance. Based on this thread (in addition to what I already explained to you in the DM), I believe your questions have been thoroughly answered. Whether you agree or want to accept it is another issue altogether.[/B]
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See below calculation require NEC

don_resqcapt19 said:
You are not reading what I am saying. I have never said that the calculations are not required.
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Calculation would be the only way
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hhsting said:

Calculation would be the only way
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Wrong. If the utility says the AFC is 25-kA, but the design documents specify equipment rated 65-kA. No calculation necessary.

Besides it was already stated the power system study is typically done after the work has started. I don’t think you have any reason to be demanding fault calculations unless it’s standard protocol for your plan submittal process.
 
xptpcrewx said:
Wrong. If the utility says the AFC is 25-kA, but the design documents specify equipment rated 65-kA. No calculation necessary.

Besides it was already stated the power system study is typically done after the work has started. I don’t think you have any reason to be demanding fault calculations unless it’s standard protocol for your plan submittal process.
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I dont see. If you have motors that contribute you still need study done even though 25kA AFC from utility

If lets say utility fault currents say 50ka and 10ka panels are provided their are motors even small ones alot of them like 300 plus elevator motors plus other motors in new high rise building sounds like calculation needed study with motor contribution needed before

Typically done after work? they need to prove compliance so typically doesnt cut it. See post# their is no spec for short circuit study
 
hhsting said:
I dont see. If you have motors that contribute you still need study done even though 25kA AFC from utility

If lets say utility fault currents say 50ka and 10ka panels are provided their are motors even small ones alot of them like 300 plus elevator motors plus other motors in new high rise building sounds like calculation needed study with motor contribution needed before

Typically done after work? See post# their is no spec for short circuit study
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Then reject the plan and be done with it.
 
I have done projects where the fault current was chosen using the infinite bus method. The equipment was required to be fully rated, but the contractor could use series rating if he provided the study.
 
hhsting said:
See below calculation require NEC



Calculation would be the only way
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You still can't read.

Calculations are required, but there is nothing in the NEC that requires the calculations be provided to the AHJ.

I am done here
 
don_resqcapt19 said:
While those sections do require the calculations, nothing in those sections requires the calculation be made available to the inspection authority as part of the permit process.

You are asking for information that the NEC does not require the engineer to provide. There are some rules where the code requires calculations to be made available to the AHJ, those sections do not.

If you want that information to be provided with the plans submitted for plan review, your local permit ordinance must specify that the short circuit study be supplied along with the plans and specifications when they are submitted for review.
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Don
I too struggle with this issue.
With respect to your second para, first sentence….how does this fit with 110.24A…last sentence. “Inspect” implies Inspection authority.
Is the author of the submitted documents not the one who should provide this ?
 
don_resqcapt19 said:
You still can't read.

Calculations are required, but there is nothing in the NEC that requires the calculations be provided to the AHJ.

I am done here
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How is that different from lets say someone provides 60a bkr #12awg cable and nothing in NEC says to upsize cable be provided to ahj? No wording in NEC that says provide or shall be provided to ahj???
 
hhsting said:
How is that different from lets say someone provides 60a bkr #12awg cable and nothing in NEC says to upsize cable be provided to ahj? No wording in NEC that says provide or shall be provided to ahj???
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Actually how is it different from grounding electrode sizing, grounding electrode I think most throughout code where does it says shall be provided to inspecting authority or to ahj or to inspector?
 
MyCleveland said:
Don
I too struggle with this issue.
With respect to your second para, first sentence….how does this fit with 110.24A…last sentence. “Inspect” implies Inspection authority.
Is the author of the submitted documents not the one who should provide this ?
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it remains my opinion that where the inspection authority wants to see this type of information, they need to have something in there permit process that requires such information to be submitted will the plans and specs.
 
hhsting said:
How is that different from lets say someone provides 60a bkr #12awg cable and nothing in NEC says to upsize cable be provided to ahj? No wording in NEC that says provide or shall be provided to ahj???
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In reality there is nothing in the NEC that requires the person requesting a permit to provide anything to the inspection authority when the permit is applied for. You get only what your permit process requires the permit requester to submit. This is not an NEC issue...it is an administrative issue.
 
don_resqcapt19 said:
In reality there is nothing in the NEC that requires the person requesting a permit to provide anything to the inspection authority when the permit is applied for. You get only what your permit process requires the permit requester to submit. This is not an NEC issue...it is an administrative issue.
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i disagree i mean come on why even have NEC code then and adopt it? 60brks on #12 awg and your saying nope let it go not in NEC? Oh its admin issue?

You want official translation? I bet they will say no its violation need to be changed but its not spelled out in NEC shall be provided to ahj to inspecting authority. Same way as 110.9 and 110.10 require calculation study but not spelled out provide to ahj or inspecting
 
Motor contribution to AIC is a lot more involved than verifying breakers vs wire sizes. The former often takes engineering expertise where the latter can be checked by Tables.
If you perceive a problem, I would suggest you advise the design professional to confirm his AIC ratings (and confirm your request).
If you start completing the calculations and there is an error, you can be as liable as the engineer.
Unless you have the credeitials and expertise to travel down that road you may place yourself and your department in liable.
But I have mentioned that previously and it fell on deaf ears.
 
don_resqcapt19 said:
it remains my opinion that where the inspection authority wants to see this type of information, they need to have something in there permit process that requires such information to be submitted will the plans and specs.
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Very well…I need to start reading into this at a few city building departments.

I brought this issue up with the State Board a few years back…
chain of events:
Did not believe that info was not being provided.
Did not have to be provided, but only a conditional permit should be issued without.
Demanded proof.
Proof provided from six departments across three counties.
Agreed info needed to be provided.
Letters sent to all departments.
Seven days letter, notify all departments assured State issue was handled on backside of project.
Projects visited after completion…zero labels on main or any mech or industrial equipment.

So how do you inspect the inspection.
 
MyCleveland said:
Very well…I need to start reading into this at a few city building departments.

I brought this issue up with the State Board a few years back…
chain of events:
Did not believe that info was not being provided.
Did not have to be provided, but only a conditional permit should be issued without.
Demanded proof.
Proof provided from six departments across three counties.
Agreed info needed to be provided.
Letters sent to all departments.
Seven days letter, notify all departments assured State issue was handled on backside of project.
Projects visited after completion…zero labels on main or any mech or industrial equipment.

So how do you inspect the inspection.
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My opinion remains that the permitting process is totally unrelated to the installation rules in the NEC. The permitting process is covered by the administrative rules that were, or should have been, adopted, when the code was adopted. These administrative rules should specify all of the documentation that is require to obtain a permit.

The code itself, does not cover the issuing of permits or even the inspection of the work. It only give the installation rules that the AHJ can use for the inspection process.
 
augie47 said:
Motor contribution to AIC is a lot more involved than verifying breakers vs wire sizes. The former often takes engineering expertise where the latter can be checked by Tables.
If you perceive a problem, I would suggest you advise the design professional to confirm his AIC ratings (and confirm your request).
If you start completing the calculations and there is an error, you can be as liable as the engineer.
Unless you have the credeitials and expertise to travel down that road you may place yourself and your department in liable.
But I have mentioned that previously and it fell on deaf ears.
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So lets say I request short circuit and motor contribution calculation and engineer provides calculated AIC rating at location X on riser without showing calculation steps and at location X has panelboard interrupt rating Greater than the calculated AIC.

Your saying that if I question the AIC at location X and steps he used if its correct or incorrect then I am liable? What if I dont question the AIC rating steps used to arrive to be correct or incorrect wont department and I be liable then?
 
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