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When I worked for the utility we used conduit ventilators at the base of the pole to improve the chimney effect of the conduit. I never saw any calculations - this was before all the high power computers & software you have today. O-Z/Gedney (OZ/G) is one of the manufactures, they come in...

Is there a formula for calculting amperes based on HP for the NEC Table 430.250? The table only goes to 500 HP and I have a 520 HP motor @ 575 VAC.

Pennsylvania is getting a lot of drilling pads for Marcellus shale. These drilling pads can have 3 MW or more of diesel generators supplying motors as large as 1600 HP. What is the appropriate electrical code for these drilling pads?

To add to dpc's comments, the fuse holder is also subject to thermal cycling. Thermal imaging of the equipment may show loose connections between the fuse and the fuse holder.

The AA-10 is a pneumatic operator on the oil circuit breaker (OCB). This is not the type/model of the circuit breaker. You are seeing the pre-insertion resistor in the 115 kV OCB.

The 225A 2KES225T rating plug is too small for a 150 kVA 480-208Y/120 transformer. The full load current on a 150 kVA, 480V transformer is 180A. Per NEC, with primary and seconday overcurrent protection on the transformer, the 480V CB-TX2 could be 180A x 250% = 450A. Like Zogzog said, change...

Does anyone know where I can get a manual for a Siemens Furnas Nordic 2000+ 91TE34AFA soft starter? Thank you.

On the diagram, each transformer is 12.5 MVA, 110/27.5kV. The two transformers serve three busses labeled 52kV. I assume the two transformers are not paralleled on the 52kV bus - either the switch -Q11 in cubicle HA06 or HA09 is open. My hand calculation (ignoring the 110kV transmission) is...

I have 5-10 kW wind turbines - each turbine has it's own inverter. I have a 146 kW PV array with one inverter. The load is 100kW @ 480Y/277VAC 60Hz. I am installing energy storage (another inverter) to be able to store excess PV energy during the day and use it at night. I want to 'island'...

I am an EE that noticed what I think is a problem with traffic signals located on the far side of the intersection. Drivers are looking at the signal and will stop for a red light where they can see the signal. Stop Here On Red signs and painted stop lines are not seen (they are looking at the...

NEC 230.50(B)(1) says protection for service cables is required "where subject to physical damage." Running SE cable down a pole is no different than running SE cable down the side of a house. NEC 338.12(A)(1) again points out the need for protection only "where subject to physical damage."...

And if you include (in)efficiency you need a 3.5kW(DC @ STC) of PV modules.

I'm having trouble understanding your company's requirements. How are you comparing capacity (kW) to energy (kWh). If I am an average 500kWh per month customer, that is an average annual energy consumption of 6000kWh. To produce 6000kWh per year of photovoltaic (PV) energy I need to install...