I'm doing an arc Flash evaluation of my bldg distribution system, and I'm trying to understand why the calories vary so much under certain circumstances.
My example is I have 2 identical 480V power circuit breakers with 600 amp trips, one breaker feeds a 400kva 480-208/120 transformer, the...
I work in a large research lab with many individual lab spaces. For the last 50 years, we have used GE DH bus duct rated at 3 phase, 208 volt, 100 amps. That product is no longer available and parts are getting harder to find, so I was wondering what others might be doing for bringing similar...
We have been using an EPO circuit for 25 years for laboratory rooms, invented by someone back in the day. It's not good but it works, usually. Sometimes it doesn't.
I attached a diagram of the circuit. Basically, diodes are used to allow for indicating lights when power is ON or when the...
I am looking at replacing the 250 watt metal halide lighting in my parking lot. It appears that the new style of fixture(Cree ARE-EDR-5M-R5) that consists of an array of LED's is not intended to have a field replaceable bulb. Cost of new fixture is about $1200. Retrofit bulbs are now available...
I have switchgear with GE AK breakers. In doing calculations(SKM Software), I have determined that if I reduce the instantaneous setting to 1.5 I can limit the arc flash exposure. My question is if I can turn the dial while the breaker is energized.
I have a situation where I have an existing 100 amp 3 phase service out of a panelboard. I would like to split the service in a junction box by terminating on a power distribution block and then feeding 3 individual 2 pole 30 amp receptacles mounted in the side of the jbox. There are #1AWG...
I have some existing parking lot 250 watt and 400 watt metal Halide fixtures. They are Lithonia Polestars. The latest searches I do seem to indicate that there are LED equivalent bulbs, but they are expensive $200- $300. Has anyone tried to do this and had any issues with overheating. The...
I have an area that is classified Class 1 - Div 2. It is for hazardous material storage, and the classification is only should leakage of vapors occur. If I need to run an analyzer and print a report to a printer via plugging standard 6' 120VAC cords into haz location receptacles, am I...
We just built a helipad and installed Flight Light HL-392 LED perimeter lights. We have been having a lot of intermittent trouble with the lights, either the remote signal not working from the approaching helicopter, or the lights coming on when they are not supposed to. Has anyone had any...
My building has 13.8kv feeders that come in underground thru manholes. We opened up one and saw some dark discoloration that appears to be not only on the cable, but on the metal cable support. Has anyone seen anything like this. Is this a "tracking" issue. All grounds are good and there have...
Here is my situation. I have a very small VFD(2hp) housed in a very large enclosure(standard Square D issue) next to a conference room. The enclosure has a muffin fan that is very loud. I want to reduce the speed of the cooling fan, since the drive enclosure is in an air conditioned room...
We had a voltage sag over the weekend. Our 13.8kv feeder dropped down to around 11.5kv
We then experienced lot of motor starters and VFD's that cutout.
When we went to restart everything, it was noticed that most of the dropouts was on newer equipment as opposed to older 35 and 50 year old...
I looked through the forums here and could not find an exact answer, but here is nmy situation. I have a 5kv chiller motor with a VFD. The VFD has a dsiplay and shows output power and output voltage. I then have CT's and PT's on the input side that I use to read a Powerlogic display on the...
I've searched through the posts here, but haven't found an exact answer. I am installing a small 600 watt output wind turbine that will go through an iverter. I don't want to tie into the grid as there is just too much paperwork for that. I'd like to take the 120VAC output of the inverter to...
I have a Square D Power Logic system that I wneed to connect PT's into. According to their diagrams, I can set it up as a 2PT,3CT 3 phase delta system.
The PT's I have are unusual(I think) in that they each have 6 leads. In the original circuit they were used in, they were wired such that 2...
I have a furnace type tool that is being designed. It's electrical load profile is 480 volts, 3 phase, 200 amps constant load, but when the tool process is in use, the current spikes to 840 amps for 6 seconds out of every minute. This process lasts maybe an hour or two, then the tool would be...
We are testing some solar panels and are trying to backfeed about 600 watts of power into our system through an existing GFCI receptacle. The GFCI keeps tripping. Grounding is installed per manufacturer, but inverter is 240 volts AC output and is passed thru 240/120VAC transformer before...
I just installed some Magnecraft 785 latching relays. The diagram indicates you apply voltage to terminal B and neutral to latch and terminal 8 and neutral to reset. I was using this with some existing relays in a room EPO circuit. What I found is that when I reset, I also was applying...
I need to power 2 loads each from a 480 volt 250 amp breaker. The temporary service is coming from outside a bldg. Can I just have a panelboard with nothing but the 2 - 250 amp breakers or do I need to provide a main breaker per NEC in the panelboard as well.
