Recent content by batman2010

Hi all, when specifying a motor disconnect switch according to art.(430.110) of NEC it shall not be less than 115% of the FLA of the motor; sticking with this formula will lead to a disconnect rating less than the rating of the circuit breaker protecting the motor which means the inrush...

Thank you for the response, this makes sense now since counting for both makes the conductors too large.

hello all, i am running feeders to (2) 3 phase , 480V, 75HP pumps. FLA for each pump is 96A and they are located at a distance of 176 feet from the panel. according to code: 96A * 1.25 = 120 A, then adjusting for voltage drop gives me #1/0 wires now do i need to add derating factor if i am...

A 3P-125A CIRCUIT BREAKER IN ANOTHER PANEL THAT IS FEEDING THE TRANSFORMER IS PROTECTING THE PRIMARY

Hello all, I have a main circuit breaker panel that is fed from a 480v-208v transformer and the transformer is required an over current protection on the secondary, would the main circuit breaker be considered as protection for the transformer secondary or it is considered as protection only to...

Thanks for the clarification, it is very helpful. MJ

THE over current protection is a circuit breaker inside the starter enclosure comes from the manufacturer and it has a contactor with an overload.

Hello folks, I am working on a project that involves (8) 3 phase, 480V, 75HP pumps fed from an existing MCC. We are replacing those pumps with new ones at the same HP ratings. The existing starters in the MCC have circuit breakers as an overcurrent protection rated at 150A. According to the NEC...

thank you for the input

I am designing a project for a sport's field lighting. There is an existing high voltage 4160V/2400V- 208V/120V 50KVA transformer for the existing field and parking lights. After selecting my new field lighting fixtures, the load would be 3 phase, 175A only for the field lights and add about...

My understanding of an emergency panel is that it has to be connected ahead of main service switch so in case of a loss in power due to a short circuit , the emergency lights will stay on. I am looking at some design drawings and i see that they connected emergency lights through a circuit...

I would say it has to be a combination starter (starter + disconnect) for it to be considered as means of disconnect. Thank you guys for the input.

Branch circuit definition is The part of a distribution system consisting of circuit conductors, between the final overcurrent protection and the outlet or load attached. [not multiple loads}

weather a "branch circuit breaker overcurrent device" is a "circuit breaker in panel" or not, i think we both agree that a circuit breaker in panel is considered a branch circuit overcurrent device and this being said it is only permitted by code to be used for motors under 1/8 hp (code)

Article 430.109 (B) clearly permits the use of a branch circuit over current device ONLY with motors of 1/8 HP or less, this means that it can't be used for larger motors, also 430.102 mentions the use of a lockable mechanism required when providing a disconnect for such motors, reference to...