just curious, I have some used 208/120 (and 480/277) panelboards with 2 pole breakers.
other than for loads you would want to turn on simultaneously (lighting loads for example), I'm trying to think what sort of equipment, if any, would use that sort of power.
I am considering using a breaker for a motor short-circuit and ground-fault protection (standard thermal-magnetic sq.d FAL series) as per NEC 430.52.
I'm not sure if this is classified as an instantaneous trip or an inverse-time breaker. I downloaded the trip curves, but its not clear exactly...
is there a rule-of-thumb for estimating U value for a plate and frame heat exchanger for a given plate material and heat transfer area?
I have the basic details, but not the details of chevron angle, plate thickness, etc. I have downloaded the PHE software, but its difficult without all teh...
Any problems with this? The design calls for a Square-D LAL36400 400A breaker, The same breaker with shunt trip is available new for a lot less from an NOS supplier. I imagine the shunt circuit can just be ignored and it will function identical to the regular breaker?
I am trying to spec a disconnect/motor controller for the following motors, all are in class 1 div 1 group D, all are 480 3ph motors
(6) 1hp motor with start/stop only
(3) 10 hp motor with VSD
Since we are in a hazardous location, I am trying to consolidate equipment to save $$
looking at...
For an industrial facility, which has all equipment hard-wired, what is the required spacing of convienience outlets? These will be placed around the perimeter of the building for temporary maintenance loads such as tools, shop vacs, portable lighting, etc. The 12' spacing for residential and...
Is there anything inherently wrong with using a motor starter that is larger than required? For example, say a 1hp motor requires a 00 starter, but I have an extra size 1 starter laying around. Assuming I use the correct thermal elements sized according to the 1hp motor, I imagine it would work...
in a 480/277 delta circuit, should I use the 1.73 factor when calculating kVA from 277 lighting currents?
In other words when calculating KVA for a 480V motor load, the formula is V x A x 1.73 /1000
if I have 3 1A lights on three legs of a 480/277, is the kVA calculated by:
3 x 1 x 277 x 1.73...
what is the rule of thumb for the size of a 3ph. (480V) motor that requires a starter? I'm assuming I can start 1-2hp motors with a simple relay energizing a 3-pole contactor circuit. The relay is controlled from an 'off/run/start' switch. I have used these types of circuits to send power to an...
First off, thatns for all the excellent advice on other threads. (You know who you are!)
We are using a transformer in our installation to go 480Delta:208Y/120 to feed office loads and receptacles. My question is what use do I have for the 208Y power? can I run (some) 240V single phase loads by...
OK, a class I group D area is defined as an area where a flammable vapor/air mixture can exist under normal operations. If this mixture is contained within a vessel, is the area around the vessel classified, or only if a flammable vapor/air mixture exists under normal operations in the...
We are installing 480/277 3phase in our building. I want to install 277V lighting fixtures that use 1.9A @ 277V. Is the following logic correct?:
1) I should try to balance the current in the circuit by running equal numbers of lights on each leg.
2) wiring three fixures on each line to...
I'm looking for any good references or rules-of-thumb for mixer scale up. Are there any rules of thumb for power input required to produce similar mixing intensity in vessles of larger sizes? Apart from being a function of viscosity, etc, is there a simple relationship between power input...
We are constructing a chemical processing facility which produces soapy water as one of its waste streams. It is primarily soapy water, sodium or potassium based. Typically this stream is diverted to city water treatment with no issues. however, our proposed plant location is in a rural area...
I am investigating using used aboveground storage tanks for biofuel. The catch is that the building department requires horizontal force calculations on any aboveground fuel tanks installed (we are in california, seismic zone 3). Manufacturers will typically provide seismic calcs for holddown...
