Plan Rejection, Load Calculations

[Npstewart]

I received the following rejection on a project we did. It is a STANDARD rejection that was obviously copied and pasted. I used the same load calc I always use for commercial, (and never have issues with) which basically breaks everything down and takes the load at 100% except the lighting which I multiply at 125%. Heres the rejection:


Please revise the Service Calculation to conform to the prescriptives in the NEC: General Lighting load as greater of connected -OR- using value from Table 220.12 NEC; Comply with NEC 600.5 for sign circuit requirements. Calculate per 220.14(F) @ 125%; Gen. purpose receptacles @ 180VA; Special purpose/ dedicated loads shall be itemized @ actual value; HVAC: greater of Heat -OR- A/C (loads per 440.34); All Motor Loads (Largest @ 125%); All continuous loads @ 125% (sign, lighting, etc.); Storage Type Water Heaters (120g or less) shall be considered (calculated/ protected as) a continuous load (125%) per 422.13. *Also, itemize the following continuous outlet loads: Illuminated Menu, Backlit signage, etc. to demonstrate inclusion.


I know it looks like its long, but like I said its standard, I know this because he cites a electric storage water heater, but my water heater is a instant gas heater. My question is, it appears he wants me to multiply EVERYTHING almost by 125%, however the NEC only says to use 125% "For the purpose of sizing BRANCH circuits". For instance, a water heater has to be taken at 125% if it is under 125 gallons, however the code states that it is only for SIZING branch circuits. So if you have a water heater that is 4500 watts, the breaker is required to be sized for 125% however, the load itself should be taken at 100%. If you read the rejection, it appears he wants me to artificially increase the load correct? Also, I usually DO increase my lighting in the load calc by multiplying my lighting load by 1.25, but this also is only supposed to be for sizing branch circuits.

Any opinions would be appreciated because I see this interpreted differently quite often, thanks.

 

[Npstewart]

Also, I think the reason why it is required to multiply by 125% (continuous load)is because 1.25 is the inverse of 80%. For continuous loads you shouldnt fill the breaker over 80%.

 

[nakulak]

imo the reason is because of the definition of continuous load. imo everything he noted is per NEC (but I am no expert)

 

[Npstewart]

Its in there, but hes missing an entire statement that says "for the purpose of sizing branch circuits".

 

[nakulak]

how about posting the load calculation and somebody can pick it apart or agree ?

 

[steve66]

Well, I do think motor feeders need the extra 25% of the largest motor calculated in. And I'm not really seeing where he is asking for everything to be taken at 125%.

I would suggest seeing if you can call the person who wrote the comment. They can probably be more specific over the phone about what they see that they don't think complies.

Steve

 

[Npstewart]

Im just going to post my revised load calculation where everything is broken down specifally. My point is that the 125% shouldn't be carried to the service calculation, it should stop at the branch circuit level. I think this revised one will work, and I do have a call/email into him.

 

[nakulak]

Its in there, but hes missing an entire statement that says "for the purpose of sizing branch circuits".

I looked at the calculation. which items are you disagreeing with ? the allowable demand factors are spelled out in part III and IV, and I don't see permitted reductions for lighting, hvac to less than 125% ? (what type of occupancy is this ?)

 

[Npstewart]

This is a fast food restaurant. I don't disagree with my own load calculation, I disagree with the reviewers comment (see original post) that certain items in the load calculation have to be multiplied by 1.25.

In my opinion you should only have to multiply something by 1.25 to size the branch circuit, hence the NEC saying "for the purpose of sizing branch circuits" that is just saying not to load a breaker more then 80% of its value for certain items such as a water heater or lighting. He is asking me to multiply certain items in the load calc by 1.25.

 

[OTT2]

This is a fast food restaurant. I don't disagree with my own load calculation, I disagree with the reviewers comment (see original post) that certain items in the load calculation have to be multiplied by 1.25.

In my opinion you should only have to multiply something by 1.25 to size the branch circuit, hence the NEC saying "for the purpose of sizing branch circuits" that is just saying not to load a breaker more then 80% of its value for certain items such as a water heater or lighting. He is asking me to multiply certain items in the load calc by 1.25.

230.42 (A) requires that you take the continuous loads at 125% unless the equipment is listed for operation at 100% of its rating!

The examples in Annex D seem to support this as well.

Your right about the standard rejection format, that's a fairly normal comment for a plan review.

 

[skeshesh]

It could be a typical response he copy pasted. Main two actions should be to itemize actual loads on other than convinience receptacles that you listed under "misc. & receptacles" and using a 1.25 multiplier for your largest motor load. Why are you not providing a panel schedule? I usually provide panel schedules for individuals small panels (100A-400A range) and do a load summary upstream of the new equipment to show the system has the capacity to serve the new load (and also verify the conductors and OCPD upstream of new installation).

 

[Smart $]

This is a fast food restaurant. I don't disagree with my own load calculation, I disagree with the reviewers comment (see original post) that certain items in the load calculation have to be multiplied by 1.25.

In my opinion you should only have to multiply something by 1.25 to size the branch circuit, hence the NEC saying "for the purpose of sizing branch circuits" that is just saying not to load a breaker more then 80% of its value for certain items such as a water heater or lighting. He is asking me to multiply certain items in the load calc by 1.25.

I don't believe that he's asking (requiring) you to do what you think. My impression is the examiner wants a more detailed calculation. One that lists loads as covered in Article 220. If what you show in your pdf is what you plan to submit, all I can tell you is that would come nowhere close to making the grade around here for a commercial job.

 

[BJ Conner]

Load Calcs

Load Calcs

Comments.
Most of the Load calculations I have seen and done are in VA or KVA.
Should the toal available be 225 Amps or 180 ( 225amps x 80%)?

 

[Smart $]

Comments.
Most of the Load calculations I have seen and done are in VA or KVA.
Should the toal available be 225 Amps or 180 ( 225amps x 80%)?

The result of a proper load calculation is a VA amount that must be made available. Continuous, non-continuous, and/or demand factoring is already included in the result. So on a service capable of delivering 225A, your load calculation result must be 225A (converted to VA) or less.

 

[Npstewart]

OK so lets say you have NO continuous loads, in theory you can load the main breaker up 80%? If you have your showing all your continuous loads, then you can go to 100% I suppose?

I was under the impression that the main breaker can only be loaded up 80% because the main breaker itself is under a continuous load.

This can be a very confusing subject.

 

[Npstewart]

One that lists loads as covered in Article 220. If what you show in your pdf is what you plan to submit, all I can tell you is that would come nowhere close to making the grade around here for a commercial job.

What else could I list or show? Would you mind posting one you have? This is a very small restaurant, the load calculation SEEMS suitable. I have used it in different states, from North Carolina to California. I haven't ever seen one that is more detailed to tell you the truth. If you do have one, it would be great to see what others are doing, thanks.

 

[steve66]

OK so lets say you have NO continuous loads, in theory you can load the main breaker up 80%? If you have your showing all your continuous loads, then you can go to 100% I suppose?

I was under the impression that the main breaker can only be loaded up 80% because the main breaker itself is under a continuous load.

This can be a very confusing subject.

If everything is non-continuous, I believe you can load a breaker up to 100%. Not everything will run at the same time, so the breaker will probably never see its full rated current. If it does see its full rated current, it will only be for a relatively short time.

 

[Smart $]

What else could I list or show? Would you mind posting one you have? This is a very small restaurant, the load calculation SEEMS suitable. I have used it in different states, from North Carolina to California. I haven't ever seen one that is more detailed to tell you the truth. If you do have one, it would be great to see what others are doing, thanks.

I don't do load calculations, so I don't have one handy. My statement above is a reflection of what I have witnessed on plans that I have performed work from.

IMO, load calculations should appear in the same manner as Annex D of the NEC, without the majority of explanatory text. Also, items which are one-or-the-other type can list both... such as general illumination could list both ft? calc and connected if larger, noting connected has been used in the totaling. Additionally showing both heat and cooling load values, even though only one is included in the totalling.

I also noticed the comment in the rejection notice about the illuminated menu, backlit signage, etc. These are an individual load type that need itemized rather than amassed under one entry for signs and outline lighting.

Regardless of how itemized you get (or not), if it appears much like the Annex D calculations, I believe yours would be better received.

 

[Npstewart]

Thanks for your opinion.

My panel schedule shows individualized loads, and notates which loads are continuous. I haven't ever seen an itemized load calculation before.

I suppose everyone shows things differently adapting to the requirements of the specific municipality.