appliances

tuhijo_2000 · Apr 6, 2015

Hello forum friends. I was hoping that someone could help me with a queation related to motor operated appliance. The total load of a motor operated appliance on a branch circuit shall not exceed what percentage. Is it 50, 70, 80 or 100%?

Marvo · Apr 6, 2015

Is this a design project you're working on or are you fixing one of your home appliances?

Standard induction motors are inefficient if they're running under low load conditions so I'd say 80-90% loaded would be fine. I'd be more concerned about the suitability of the motor for the type of duty cycle you're using it for.

View attachment S1_dutyCycle.pdf

davesparks · Apr 6, 2015

From the terminology this sounds like a question related to the NEC rather than BS7671, But unless the OP can rewrite it in such a way that makes sense we may never know what he's trying to ask?

tuhijo_2000 · Apr 6, 2015

Marvo said:
Is this a design project you're working on or are you fixing one of your home appliances?

Standard induction motors are inefficient if they're running under low load conditions so I'd say 80-90% loaded would be fine. I'd be more concerned about the suitability of the motor for the type of duty cycle you're using it for.

View attachment 28731

Well, actually is neither. I am going to have a test for employment. The position does not require any electrical repairs. The job if for autorepair. My brother in law has the same position at this job and he stated that for some odd reason , the company include alot of questions that does not relate to the job to be performed. Go figure. He provided me with a copy of the test and that is one of the questions. i honestly doubt that i will ever encounter an appliance inside of a car. I can understand if i was required to work on Recreational vehicles. But that is not the case.

Marvo · Apr 6, 2015

Maybe I misunderstood your question. What size branch circuit does your question refer to and is the appliance fixed or not? There are NEC defined limits on 15 and 20A circuits;

15 and 20 ampere branch circuits. A 15 or 20 ampere branch circuit shall be permitted to supply lighting units, or other utilization equipment, or a combination of both. The rating of any one cord-and-plug-connected utilization equipment not fastened in place shall not exceed 80 percent of the branch-circuit ampere rating. The total rating of utilization equipment fastened in place, other than luminaires, shall not exceed 50 percent of the branch-circuit ampere rating where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.

tuhijo_2000 · Apr 7, 2015

Marvo said:
Maybe I misunderstood your question. What size branch circuit does your question refer to and is the appliance fixed or not? There NEC defined limits on 15 and 20A circuits;

I really don't have a clue. I did read the article you sent and noticed that the question on the test does not specify if its a fixed applianceor not. I do appreciate your help. You are awesome.
Sergio