To be more specific; I used NFPA 70E equations D.8.2 and D.8.3 to determine the incident energy and also used Table D.8.7 and got very different answers. Unless I really screwed up the math I don't know why the results are different.
Can someone direct me to a clear explanation of the equations shown in Annex D of NFPA 70E? I have been trying to reconcile some calculations I did recently and am coming up with widely different answers.
I am unsure how to determine what "adjacent" means when refering to a Class I hazardous area. I am reviewing some old building prints which define the area withing 12' of the floor as Class I Division I. Does that mean that the rest of the room above 12' is Division II. I also have a Div I...
If the grounding system at a building is acceptable now how often should the ground resistance be tested to ensure continued performance? I am concerned about the integrity of the buried grounding electrodes.
Is there a difference between a contact described as positive-break versus one described as force-guided? I think they are actually of different construction but am confused by my readings of many descriptions.
I was given some ONSET HOBO data loggers to integrate into a Siemens building control system. Has anyone communicated between the ONSET Remote Site Manager software and the Siemens building control software. Everyone tells me there is a way but cannot be more specific.
I am to copy an existing e-stop circuit to a new project. I'm not sure about some of the existing design details. Can I use a standard momentary pushbutton with a mushroom head as an e-stop into a safety relay? I think the relay would still actuate correctly if one N.C. pushbutton contact...
I am writing a spec for a transfer switch from an old source I found. That spec specifically prohibited the use of an in phase monitor for the switch. Why would I not want in phase monitoring?
I have always used NFPA 79 to size the main disconnect in a control enclosure. We are redoing a machine headed to Ontario and I don't have a Canadian electrical code handy. Are there different requirements for a main cabinet disconnect in Canada?
Has anyone some experience with the A-B Drive Executive software and a 1305 drive? I'm interested in the programming connections and cables necessary. I ask in the forum as I cannot contact my local AB rep at this time.
I am learning on the job about aircraft fueling hydrant pits. My reading of literature suggests that there is no longer a requirement for electrically bonding the fueling equipment during fueling. I am looking for requirements to bond the hydrant pit and other electrical devices to the earth...
I have been asked to provide an E-Stop at an aircraft fueling hydrant pit. I am new to design of such equipment but am unsure of the requirement for this and have not seen this equipment on any of the hydrant pits I inspected. Could someone direct me to the pertinent safety or design...
