Does anyone follow Table 220.12?

[Mr. Bill]

I tend to ignore the values in table 220.12. Most energy Codes are 2 to 3 times more strict. Yes, burn me at the stake, I'm ignoring a portion of the Code. Do I really need to provide (2) 120V circuits for lighting in a 900sf classroom (900 * 3VA = 2700VA) if the State's energy code limits the room to 1350W (900 * 1.5W = 1350W)? Does HVAC also need to use this table for heat load calculations? This would oversize the cooling systems. Really seems like a waste of money if another Code limits energy use.

Does anyone follow Table 220.12? Or am I reading it wrong?

 

[LarryFine]

Do I really need to provide (2) 120V circuits for lighting in a 900sf classroom (900 * 3VA = 2700VA) if the State's energy code limits the room to 1350W (900 * 1.5W = 1350W)? Does HVAC also need to use this table for heat load calculations?

I believe these numbers must be used for load calcs for the service, not that you must actually run those circuits.

 

[bphgravity]

I too feel Article 220 is on the conservative side and does not realistically represent the demand of loads in a typical building. With that said, the calculations required in Article 220 have nothing to do with energy calcs. So, I am not really sure what point you are trying to make... ???

 

[Mr. Bill]

So, I am not really sure what point you are trying to make... ???

Do I really need to provide (2) 120V circuits for lighting in a 900sf classroom (900 * 3VA = 2700VA)...

II. Branch Circuit Load Calculations
220.10 General. Branch-circuit loads shall be calculated as shown in 220.12, 220.14, and 220.16.
220.12 Lighting Load for Specified Occupancies. A unit load of not less than that specified in Table 220.12 for occupancies specified therein shall constitute the minimum lighting load. ...
Table 220.12
...
Schools 3 VA/sf
...

I brought this up on another thread and rather than divert from the OP I started a new thread. I've never had plan review or an inspector ever mention this section. I've never known another engineer follow this. I thought I'd ask the question to a larger group. Maybe I'm misreading it. It sounds like it's for branch circuit sizing like the 180VA per receptacle.

 

[steve66]

Yes, I always use this for sizing the service and feeders. But never for the branch circuits. You only need to provide branch circuits for what's actually installed.

Yes, the energy code usually only allows 1 VA per sq ft. for lighting, but with all the computers now, I'm not sure 1 va per sq ft is enough for receptacles.

And sometimes you can apply demand factors to the table (table 220.14 for example).

After all, its usually nice to have some spare capacity on the service.

Steve

 

[charlie b]

I believe a state code in my neighborhood tells us that, when sizing the service, we need only provide for the lighting loads permitted under the energy code.