Commerical Panel Load Calc

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I have an existing panel load calc sheet. On the sheet is are a few entries i don't know how to calculate. The panel is a 225a bus 120/208 3phase.
It is fed with 250mcm CU. It is mostly used for slot machines and a few odd lighting circuits, but we are adding a few poker tables and need to permit the job and provide a load calculation.

1. Panel Demand KVA?
2. Panel Demand Amps?
3. High Phase Amps with LCL?

Thanks Dave
 

bob

Senior Member
Location
Alabama
I have an existing panel load calc sheet. On the sheet is are a few entries i don't know how to calculate. The panel is a 225a bus 120/208 3phase.
It is fed with 250mcm CU. It is mostly used for slot machines and a few odd lighting circuits, but we are adding a few poker tables and need to permit the job and provide a load calculation.

1. Panel Demand KVA?
2. Panel Demand Amps?
3. High Phase Amps with LCL?

Thanks Dave

IMO 1 and 2 are the same thing. You are looking for the peak KVA demand that will occur on the panel during a selected time period, usually 15 or 30 minutes. In a commercial environment the lights and A/C will be estimated at 100%. You then must consider what other loads may add to this load during the time period. As for a #3, what is LCL?
 

Smart $

Esteemed Member
Location
Ohio
IMO 1 and 2 are the same thing. You are looking for the peak KVA demand that will occur on the panel during a selected time period, usually 15 or 30 minutes. In a commercial environment the lights and A/C will be estimated at 100%. You then must consider what other loads may add to this load during the time period.
Ummm... that would be selected time periods... over required number of days. IIRC, that would be 30. Alternative Article 220 feeder calculation.

As for a #3, what is LCL?

I assume it's regarding a delta hi-leg service (e.g. 240/120 3? 4W). LCL = Line—Center-tap—Line.
 
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bob

Senior Member
Location
Alabama
Ummm... that would be selected time periods... over required number of days. IIRC, that would be 30. Alternative Article 220 feeder calculation.

No it would not. The OP wants to calculate the demand not measure it. I might agree if the OP wanted to take a meter and measure the demand. If so you would be correct in referring to the NEC requirement of 30 days. In this case your statement is wrong.
 

Smart $

Esteemed Member
Location
Ohio
No it would not. The OP wants to calculate the demand not measure it. I might agree if the OP wanted to take a meter and measure the demand. If so you would be correct in referring to the NEC requirement of 30 days. In this case your statement is wrong.
By all means, please elaborate... specifically, the use of this calculation as you describe it. Perhaps cite a reference or three.

I don't purport to be correct 100% of the time Often, after due diligence I will figure out if I am blatantly wrong. But this one is escaping me so far ;)
 
Panel Calc's

Panel Calc's

IMO 1 and 2 are the same thing. You are looking for the peak KVA demand that will occur on the panel during a selected time period, usually 15 or 30 minutes. In a commercial environment the lights and A/C will be estimated at 100%. You then must consider what other loads may add to this load during the time period. As for a #3, what is LCL?

#3 LCL == > High Phase Amp With Long Continous Load

On these load calc sheets there is a difference between "straight" KVA and Panel Demand KVA? How is that calculated ? As I understand it - KVA is just P=I*E*1.73 with KW => P=I*E*1.73 * pf.
Thanks Dave
 

inspector141

Senior Member
Location
Westminster, MD
Dave,

Straight KVA is all the loads added up.

Demand KVA is using all of the demand allowances in article 220. Such as table 220.42, table 220.44, 54, 55...

In addition, a demand could omit non-coincidental loads (220.60)such as an A/C and an electric VAV box, in which case you omit the smaller of the two.

Once completing the demands, you now have a calculated load for the feeder and panel. The panelboard and its feeder can be sized based on this demand load. Many designers would allow for future loads, but the NEC does not require it.
 

bob

Senior Member
Location
Alabama
#3 LCL == > High Phase Amp With Long Continuous Load

On these load calc sheets there is a difference between "straight" KVA and Panel Demand KVA? How is that calculated ? Thanks Dave

Your panel schedule shows the panel connected KVA. You have to determine what the demand KVA will be. I am not familiar with the load of a poker table or slot machine so I can not help you.

Smart
The NEC guides you thru the process of sizing the panel. You know that the panel size will be greater that the actual demand on the panel. You have applied the NEC load factors when arriving at the panel size. You will need you vast experience and High IQ to make a decision as to what you think will be the actual demand. I would agree that the most accurate way would be to put a recording meter on the panel, but that would be done after the job is completed.
 
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Smart $

Esteemed Member
Location
Ohio
Smart
The NEC guides you thru the process of sizing the panel. You know that the panel size will be greater that the actual demand on the panel. You have applied the NEC load factors when arriving at the panel size. You will need you vast experience and High IQ to make a decision as to what you think will be the actual demand.
I don't know who you think you are talking to, but I assure you, your condescending approach to this discussion earns you no points with me.

I would agree that the most accurate way would be to put a recording meter on the panel, but that would be done after the job is completed.
(I suppose it's my turn ;)) Do you even understand the requirements of Article 220?

The NEC prescribes two methods of feeder sizing (i.e. minimum ampacity rating, for which the panel must be rated equal or greater) in Article 220. It takes no vast experience and High IQ to do the calculations. Yes the understanding of the requirements may be daunting for the greenhorn (which again I feel compelled to assure you I am not).

If you have an existing panel that you want to add loads to, you have two choices under the NEC: 1) do a load calculation per Article 220, or 2) do a demand recording of 30 days per Article 220. Per the NEC this is the end of the discussion. However, if you believe you have a better method, you are more than welcome, and I invite you, to join in the code making process at any time, even though you may have to wait years for any change to take place.
 

bob

Senior Member
Location
Alabama
I don't know who you think you are talking to, but I assure you, your condescending approach to this discussion earns you no points with me.

I meant no disrespect to you. I was trying to lighten up on the discussion but I did respect you experience is solving this problem. I apologize if this offended you. It was not my intent.
 

bob

Senior Member
Location
Alabama
If you have an existing panel that you want to add loads to, you have two choices under the NEC: 1) do a load calculation per Article 220, or 2) do a demand recording of 30 days per Article 220. Per the NEC this is the end of the discussion.

You are correct. In the post it says that he has the existing load calculation sheet. To me this sounded as though he had already made the NEC required calculations
and was trying to determine the max demand that would be the real world demand and not that determined by the NEC. After re-reading the post I apparently misunderstood
what was wanted.
 
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