Jerramundi
Senior Member
- Location
- Chicago
- Occupation
- Licensed Residential Electrician
Hey guys, I hate to come back with another Electric Range question, but I need some clarification from the masters!
This time I have a 120/240v Electric Range w/ a nameplate rating of 14kW.
In previous discussions, you all clarified for me that Table 220.55 and the subsequent Notes #1 - #3 were for Service and Feeder Load calculations ONLY.
That Note #4 is for Branch Circuit Load calculations.
My first question is... if Note#4 makes it permissible to utilize Table 220.55 to calculate the Branch Circuit Load for a single Electric Range, does that then make Notes #1 - #3 applicable for the same calculation?
In other words, for my 14kW nameplate rating, am I correct to apply Note #1 and increase the Column C Maximum Demand of 8kW by 5% for every additional kW over 12kw (14kW - 12kW - 2kW; 2 x 5% = 10%) to a Maximum Demand of 8.8kW?
I understand the heating elements cycle, but this just seems really low for a 14kW nameplate rating. For multiple units I understand this in terms of how it applies to Service and Feeder Load calculations as they are assuming not every element of every unit will be used at once... but again 8.8kW just seems really low for a nameplate rating of 14kW.
My second question is... if this is a Chord and Plug Connected Load do I need to size the Branch Circuit up to 50A?
Assuming my calculations in part one are correct and my calculated load is 8.8kW... 8800W/240V = 36.67A and I would utilize a 40A circuit, but 80% of a 40A circuit is only 32A... thus, should the branch circuit be increased to 50A to accommodate the chord and plug 80% limitation?
My third question is... should the branch circuit need to be increased to 50A... are we talking ONLY talking about the branch circuit conductors when we say a chord and plug connected load cannot exceed 80% of the branch circuit rating?
In other words, given the calculate load of 36.67A, could I utilize a 40a equipment chord and a 40 receptacle on a 50A branch circuit w/ a 50A OCPD?
My fourth question is... can anyone explain to my why this 80% rule applies for a dedicated circuit? I understand, for example, if there were other receptacles on the circuit and additional things plugged in why you would want to limit a chord and plug connect load... but why for a dedicated circuit?!
My fifth and final question is... if I were to just say forget the chord and plug option and go hardwired, do I technically need a disconnect within sight of the unit? I know a disconnect for an electric range sounds like madness, but this is the result of having my nose in the NEC, haha.
Thanks in advance for all the help,
Jerramundi
This time I have a 120/240v Electric Range w/ a nameplate rating of 14kW.
In previous discussions, you all clarified for me that Table 220.55 and the subsequent Notes #1 - #3 were for Service and Feeder Load calculations ONLY.
That Note #4 is for Branch Circuit Load calculations.
My first question is... if Note#4 makes it permissible to utilize Table 220.55 to calculate the Branch Circuit Load for a single Electric Range, does that then make Notes #1 - #3 applicable for the same calculation?
In other words, for my 14kW nameplate rating, am I correct to apply Note #1 and increase the Column C Maximum Demand of 8kW by 5% for every additional kW over 12kw (14kW - 12kW - 2kW; 2 x 5% = 10%) to a Maximum Demand of 8.8kW?
I understand the heating elements cycle, but this just seems really low for a 14kW nameplate rating. For multiple units I understand this in terms of how it applies to Service and Feeder Load calculations as they are assuming not every element of every unit will be used at once... but again 8.8kW just seems really low for a nameplate rating of 14kW.
My second question is... if this is a Chord and Plug Connected Load do I need to size the Branch Circuit up to 50A?
Assuming my calculations in part one are correct and my calculated load is 8.8kW... 8800W/240V = 36.67A and I would utilize a 40A circuit, but 80% of a 40A circuit is only 32A... thus, should the branch circuit be increased to 50A to accommodate the chord and plug 80% limitation?
My third question is... should the branch circuit need to be increased to 50A... are we talking ONLY talking about the branch circuit conductors when we say a chord and plug connected load cannot exceed 80% of the branch circuit rating?
In other words, given the calculate load of 36.67A, could I utilize a 40a equipment chord and a 40 receptacle on a 50A branch circuit w/ a 50A OCPD?
My fourth question is... can anyone explain to my why this 80% rule applies for a dedicated circuit? I understand, for example, if there were other receptacles on the circuit and additional things plugged in why you would want to limit a chord and plug connect load... but why for a dedicated circuit?!
My fifth and final question is... if I were to just say forget the chord and plug option and go hardwired, do I technically need a disconnect within sight of the unit? I know a disconnect for an electric range sounds like madness, but this is the result of having my nose in the NEC, haha.
Thanks in advance for all the help,
Jerramundi