Neutral calculation

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ciupol

Member
Location
Fargo, ND
Have a question about calculating neutral load for the service. In example D1(a) in Annex D in the section for neutral load calculation dryer is included in the calculation (at 70%). In the description for this example it is stated that dryer is a 240V equipment. Why do we have to include dryer in neutral calculation? I thought that 240V loads do not generate neutral current.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
A true 240V load does not put any load on the neutral. (In a normal residential system, that is.)

But most driers are 120/240V devices. I would expect only a small neutral load for the 120V motor and controls, but perhaps some driers have high 120V loading, say for low temperature operation.

-Jon
 

ciupol

Member
Location
Fargo, ND
Thanks for the answer.
One additional question though. So how can one know which loads should be included in neutral calculation? Should I always include all loads, even those marked 240V in the calculation?
 

Smart $

Esteemed Member
Location
Ohio
Thanks for the answer.
One additional question though. So how can one know which loads should be included in neutral calculation? Should I always include all loads, even those marked 240V in the calculation?
Only 240V 1? 3-wire equipment, i.e. 120/240V. Cooking appliances, clothes dryers are the typical residential loads; some HVAC equipment...

No 240V 1? 2-wire equipment.
 
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