I would question how effective turning off the switchboard would be with the power off. The current through the components is what causes the temperature differential. Once de-energized the component start cooling off skewing the results. Best bet is put in the IR windows.
Agreed, the autotransfer switch will be locked in the emergency position & the circuit breaker feeding it from the substation will be locked out as well.
We are looking to back feed power, in case of loss of our generator, through a circuit breaker from a branch feed used to load bank test a generator. The breaker will be a Square D PGA36100SA rated to 1000 amps at 480 volts. All other power to the building will be down while repairs are made to...
We are getting ready to do a major electrical shutdown to service our 13.2 kv switchgear. While we are down there are serveral items that get done on a regular basis including the DRLO scan of the busses & feeders. We have IR scans done every year and I am wondering about the value of the DRLO...
You could plan for worst case by using the short circuit current energy plus the heat of combustion at about 19,660 Btu/lb 45.7 MJ/kg assuming mineral oil coolant. Converting energy into blast pressure is beyond my understanding though.
DPC - the manufacturer has placed no stickers or anything on the tool indicating it was built to any specific code or went through any 3rd party testing. I was thnking it was refered to in general under 29 CFR 1910.303 or something and all of the standards spelled it out. I can't find anything...
Just received a large tool to install that has a large area open for ventilation. I would be fine with that except a 6" wide by 36" tall part of that area leads into the electrical controls at 480V. Are there requirements for electrical cabinets to be enclosed, finger safe, and of sufficient...
Apparently we have tools that operate at 13.6 mhz and 2.54 ghz and I've been asked if we need to add RF & MW guidelines to our electrical safety policy. All the emmissions are supposed stay inside the tools but we have technicians that check boards and subassemblies that have busses with those...
Sorry didn't complete the reply.
(C) Other Space Used for Environmental Air. This section applies to space used for environmental air-handling purposes other than ducts and plenums as specified in 300.22(A) and (B). It does not include habitable rooms or areas of buildings, the prime purpose of...
The raised floor in the cleanroom is only an air plenum as much as the area above a suspended ceiling used for return air is an air plenum. The NEC handbook specifically uses a return air plenum above the ceiling as an example.
The 2009 NFPA 70E section 130.3 requires an arc hazard analysis be done at every major renovation or modification, and periodically not to exceed 5 years. Short circuit and coordination studies are part of that. The section states the design of the protective device, it's opening time and...
Standard electical code applies, use the NEC. Note a warehouse doesn't usually meet the exception for supervised industrial installation in section 240.
Most violated sections I run into are the ones for working clearances & dedicated spaces around disconnects and circuit breaker panels.
Am I being overly restrictive and costing the company more money than necessary?
Our cleanroom floors are used for return air and running various utilities to the manufacturing tools. As such I believe they fall into the "other space used for environmental air" described in NEC 2008 300.22(C)...
I have been tasked with generating our electrical safety policy &, If I am reading OSHA 1910.335 and the NFPA 70E correctly, it would appear that anyone working on live electrical circuits above 50 volts needs to wear insulating gloves and protectors. Having worked my way through college as a...
A brand name motor drive manufacturer writes:
"Motor size is often increased by 1.2 to 1.5 times for load applications such as fans, blowers and pumps. Consequently, the motors in such applications are generally operating at 70% rated capacity when the rated output of the equipment is reached...
All chambers are 120Vac, 26A, single phase.
Transformer is a standard Square D and the name plate is on the link.
http://www.geocities.com/v6racer.geo/pictures/DSC04702.jpg
It overheated and shorted but not necessarily in that order. The picture below show the center winding. Testing with a DMM show all phases shorted together and to ground.
The transformer feeds a 225a 208v circuit breaker panel with 11 circuits. The loads are mostly 26A single phase...
