NEC 502.4(B)(4) requires all boxes and fittings to be "dusttight". NEC 500.2 defines dustight as "enclosures constructed so that dust will not enter under specified test conditions". It has a fine print note:
FPN: See ANSI/ISA 12.12.01-2000, Nonincendive Electrical...
I would like to modify my question above.
Given the above IEC 309 receptacles, is it against the NEC to have some 30A and/or 60A receptacles that would be energized by motor starters and others of the same exact pin configuration that are always energized by feeder circuit breakers all in the...
jbartos
Based upon your reply, my comments are then:
1) Is having the 100A circuit breaker (albeit with adjustable overloads) protecting a 60A receptacle in violation of 210-21(b)(1)?
2) A 20hp or 25hp load could be connected with a 60A plug to the setup that I described and this would be...
I would like to install a 480V, 3ph, 60A, 40hp rated IEC receptacle on the load side of a 100A CB, IEC 60A contactor, and 23-75A adjustable electronic overload for a 30hp motor. I have used receptacles many times to feed portable motor loads that have a portable motor starter on them, but this...
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I am looking for design references for busbar design. Specifically the physical design of bolted joints of busbar and the physical design for bracing due to magnetic forces induced by fault currents. My application is for 250VDC around 1000A but any reference would be fine.
Also if anyone...
Here are my comments for what they are worth:
Per ELECTRICPETE on 10/23, I have never heard of that phenomena. Most of the ungrounded systems that I have seen out here in California are ungrounded wyes but PG&E never used GE padmount transformers, usually Cooper.
Per WTHALL on Oct. 24, since...
Thanks again to everyone for their replies. I have learned some additional information. The starter panel is supposed to be designed to UL508A. A copy of this is around $400. There are ampacity tables in the standard. I feel that the standard was not followed so I will probably buy a copy...
For NEC Table 310-17, what is the definition of "free air"? A major manufacturer of motor control equipment has sized conductors to motor starters inside enclosures (such as a Hoffman NEMA 4 enclosure) based upon Table 310-17, ampacities in free air. I have always used this table for...
For standard fire pump installation (from utility not a generator) I agree DRWeig and partly with dpc. DRWeig is correct for the reasoning behind the code rule. dpc is correct except that the conductors don't have to be oversized, this is an exception to the overcurrent protection rule (motor...
Thanks everyone for the suggestions.
I know that 300hp is not "large" for everyone, however I usually try to use 4160V, not 480V, for anything over 200 to 250hp.
I also used an incorrect term. "Derate" (or adjustment) is the term the NEC uses for accounting for more than...
I am sizing motor leads to a 300hp motor. Per NEC, I need ampacity of 361A x 1.25 or 451A. The installation is in a locale that gets very hot. Temperatures over 110 deg. F are not uncommon. Using derate of .82 for 75 deg. C conductors at 105 - 113 deg F. ambient and code requirement of...
I have designed charging rooms for golf carts. Contact Club Car (leading manufacturer of golf carts) and they have design guidelines. What you are proposing is overkill. Just interlock your exhaust and makeup air system and the hydrogen monitor to the charging equipment. If the exhaust...
