HVAC Load calculation

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Electriman

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Greetings,

What is NEC accepted method to calculate the HVAC condenser electrical load? is multiplying the MCA (minimum circuit ampacity) by voltage accepted by NEC?
 
Electriman said:
Greetings,

What is NEC accepted method to calculate the HVAC condenser electrical load? is multiplying the MCA (minimum circuit ampacity) by voltage accepted by NEC?
Click to expand...

It's already done for you, just follow the label posted on the unit.
 
Electriman said:
Greetings,

What is NEC accepted method to calculate the HVAC condenser electrical load? is multiplying the MCA (minimum circuit ampacity) by voltage accepted by NEC?
Click to expand...
That's how I do it on a new design where load is not really an issue. Just remember that the MCA already has 25% built in to it. For a remodel, where I am trying to get things to work in an existing service, I will use the FLA or RLA for load. I think either way is acceptable to the NEC for service sizing.
 
Electriman said:
Service load
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2017 NEC Section 220.5(A) "Voltages: Unless other voltages are specified, for purposes of calculating branch circuit and feeder loads, nominal system voltages of 120, 120/240, 208/120, 240, 347, 480/277, 480, 600Y/347 and 600 volts shall be used".

To select conductor sizes refer to 310.15(A) & (B).
 
Knightryder12 said:
That's how I do it on a new design where load is not really an issue. Just remember that the MCA already has 25% built in to it. For a remodel, where I am trying to get things to work in an existing service, I will use the FLA or RLA for load. I think either way is acceptable to the NEC for service sizing.
Click to expand...
Does FLA or RLA consider both compressor and fan?
 
Electriman said:
Does FLA or RLA consider both compressor and fan?
Click to expand...
On the nameplates I normally see each motor is listed separately as far as FLA and or RLA.
Then again, I am normally only interested in MCA & MOCP.
 
"Loads are calculated on the basis of volt-amperes (VA) or kilovolt-amperes (KVA) rather than watts or kilowatts (KW) to calculate the true amperes values. However, the rating of equipment is given in watts or kilowatts for noninductive loads. Such ratings are considered to be equivalent of the same rating in volt-amperes or kilowatt-amperes".
 
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