I have a three phase 4 wire panelboard (3-phase + neutral). This panelboard is about 150 feet from the transformer.
Is it required that the neutral wire has to come directly from the Y point of the transformer? Or can use the ground wire near the panelboard as a neutral?
In transformer, the Y point of the secondary is connected to ground. Can we connect the body of the transformer with the same Y-point (for equipment grounding)?
Also can we ground the generator in the same way as transformer (connect the Y point of generator to ground)?
If we put a terminal block in an enclosure, for example universal-enclosure of Schneider, then do we need to consider the short circuit rating of only of the terminal blocks, or short circuit rating of enclosures as well?
I need to size the circuit breaker for a 208V feeder that supplies power to three 5HP motors in parallel. Vendor will take care of the overload and short circuit protection of individual motors. I only have to size the thermal magnetic circuit breaker for the main feeder that supplies power to...
I need some help in sizing the breakers of transformers. We have following equipment.
1. 300 kVA Utility Transformer (12.47kV – 480V). (There is a 460V fire pump motor on this utility transformer)
2. Then a 480V transfer switch
3. Then a 150 kVA transformer (480V-208V)
4. Then a 208V panelboard...
I have to specify electrical equipment (like panelboard, light fixtures, etc) in an airport-hangar. The hangar has walls and roof but the problem is that it has a very large door from which the planes will come in and go out. In addition to this large door, there are two small doors as well.
I...
Does anybody know how to connect a load-bank to a transfer-switch?
I understand that load-bank will be connected at the terminals of the transfer-switch and will be in parallel to generator. Please let me know comments...
I am relatively new to NEC, and need some help in sizing the breakers for lighting fixtures and non-motor load.
For example, maximum how many 400W Metal Halide lighting fixtures can be placed on breaker of 20A 120V single-phase?
And how many watts of non-motor load can be placed on a 15A...
Is GFP (ground fault protection) a requirement for 480V distribution panel in NEC world?
We have a utility transformer (12.47kV – 480V), then a 480V distribution panel, then a dry type transformer (480V – 120/208V) and then a 120/208V distribution panel.
I understand that GFP is not required...
I have a three core power cable and a single core ground cable, both cables are going to a motor.
I need to put a junction box for both of these cables before motor. In other words I need to put a junction box in between power supply and motor.
Now can I ground the body of the junction box...
We are installing a distribution panel in a building. The building has sprinklers. So a weatherproof (Nema 3R) panel will be required. The problem is that it can be dangerous in case the sprinklers go off at the same time when someone is performing maintenance at the panel.
If we put a warning...
I have to start a 100HP fire pump motor; the maximum allowed voltage drop at motor starting is 15%.
Can this be accomplished with a stand-by generator of 300kW? Thanks for your help.
We have an explosive (class 1 Div 2) building that has to be air-conditioned. The air-conditioning units will be placed on the roof.
The problem is that the air conditioning unit will suck the explosive gas from inside the building, and so the roof top air-conditioning unit should also be...
I am wondering what does NEC 110.26(E) imply. Does it mean that all electrical equipment should have a space of 6 feet at the top? 6 feet appears to be too much.
I am trying to put a 5 feet tall panelboard in a 10 feet high room. is it possible?
What should be the conductor size to ground 100HP 208V fire pump? The fire pump is fed directly from the 208V secondary of the transformer. There is no overcurrent protection in between transformer secondary and fire pump. However there is 30A circuit breaker on the primary side (12.47kV) of the...
Let’ say if there are ten motors on a bus fed by ten breakers then we have to consider the short circuit current contribution of all ten motors in order to size the bus.
What about the sizing of each breaker? Should the short circuit contribution of all ten motors be considered for the sizing...
I have a question about the short circuit rating of the capacitirs. Can an automatic power factor correction capacitor which is rated for 30kA, be used at a location of 50kA if a current limiting fuse/breaker is used as the incomer of the capacitor bank?
