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...
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...
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...
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...
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...
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...
my understanding is a "listed molded case circuit breaker" definition is that it is a single separate breaker that is not part of an electrical panel. I am basing this assumption because in article 430.109(B) it shows the exception to use a circuit breaker in panel (branch circuit overcurrent...
I used to believe that a circuit breaker in panel can be used as a disconnecting means for motor loads like in boiler rooms when the panel is within site until i read Article 430.109 in the NEC (NFPA 70) defines the type of disconnecting means allowed for motors and controllers. I am concluding...
Hello all,
I would appreciate any input on this,
I am having talks back and forth with the electrical contractor regarding grounding a newly installed transformer in the electrical room to existing grounding system, that is what the plan calls for. His problem is that he can't locate or find...
Thank you guys for the feedback, they already shut down the system and I am trying to coordinate with the owner since they are coming back at me. My only excuse that if it is not a code issue to disable the FA system!
