I am not sure the voltage and current of the remote start circuit as this is for a temporary generator connection at a hospital that is only brought on site temporarily from time to time. The existing installation has the 2#14 generator start with the 3phase,4Wire, 480V feeder from a tap box...
I just ran by an issue where I have a 3phase, 100A disconnect feeding (2) 3phase, 50A disconnects that serve electric space heaters. The load side of the disconnect has (3) #2AWG feeding into a wire gutter where Polaris splices were used to splice down to (2) 50A feeders at #8AWG each going to...
All, thanks for clearing it up and hanging through my brain fart. So when it comes to motor loads, increasing the line resistance (and subsequently the voltage drop at the motor) will result in increased energy losses (i.e. bigger bill) which is why the Energy Code incorporated the voltage drop...
Ouch Waross... Thanks for not touching on any of the questions in the comment and for providing a short comment that is obviously insulting and not helpful. My original response was that an increase in voltage drop is due to an increase in losses in the line, which would increase the power being...
The new California Energy Code has adopted the fine print notes of the NEC for voltage drop. I am well aware of the undesirable affects of excessive voltage drop on circuits, especially motor loads (decrease in starting torque and overheating of the winding) but me and a coworker were wondering...
NEC allows for a maximum 250% the FLA of a motor for an inverse-time CB. Is there somewhere in the NEC that allows you to use a 20A CB as the minimum CB size for protecting motors?
As an example, I have a 1-1/2HP 460V, 3PH motor with an FLC of 3A. 3A x 2.5 = 7.5A, so does the circuit...
Davidbeach,
Ah ok I see, I was mixing things up in my head.
Magoo2,
I would really like to see those traces but I don't see them in your post?
Also, can you tell me if my understanding below is correct:
If the network is an ideal, pure resistive network, the fault current would be...
All,
I have been a little unsure about this, so I was hoping the community could help clear it up for me. For a 3 phase, Wye distribution, I have read that a three phase bolted fault is a balanced fault and a single line to ground fault is an unbalanced fault.
If a three phase bolted fault...
DPC, you're right and I didn't mean to imply the panel was rated for arc flash (obviously that is really incorrect). Obviously arc flash incident energies are for determining PPE requirements for live work.
I meant to say the explosion resulting from the fault. I thought, that depending on...
Gotcha. So there really isn't any restrictions to how many knock outs you can add to a panel? I feel like at some point wouldn't it undermine the panelboards ability to withstand the forces imposed on it during an arc flash incident?
Although I just called some other contractors I know and...
Hey All,
Did a search and couldn't find a previous post... Does anyone know if it is acceptable to add a knock out to the side of an existing panel in which there is no more room on the top of the panel for a new conduit? Would doing this void the UL listing of the panel?
Thanks for any...
All,
I think you all have very good points, and I feel the topic could be argued to eternity... I guess no matter what, it falls on the worker to read labels prior to working and to follow procedures (and hopefully the employer has put in place good maintenance procedures).
Hamburger,
Light...
Waross,
Agreed changing the trip time does not lessen the arc intensity but lessens the clearing time of the arc which impacts the energy at the fault.
I wrote the statement too fast. I agree the location of the arc has no affect on the magnitude of the arcing fault current, as this depends...
I didn't realize the fault current through the upstream device that is tripping would be different, but now that I think about it, it makes sense. I had read the equations of IEEE 1582 on how to calculate the arc fault current, but I didn't realize it also had equations for determining the...
We have a project where we will be installing a new Eaton Magnum DS Low Voltage Switchgear with an arc flash reduction maintenance switch.
1. Does the maintenance switch set the main breakers to their lowest settings to reduce arc flash hazard while working on the gear?
2. If so, should the...
I am using SKM to perform a power system analysis (short circuit,coordination, and arc flash). When performing he arc flash calculations through the software per IEEE 1584, the table summary gives me the bus bolted fault current, bus arcing fault current, protective device bolted fault current...
