October 31
Tracking Arc Flash in Australia sets worker’s clothing on fire.
This type of arc is not even talked about in the literature. Dr. David Sweeting of Australia and I have been working in our papers to bring it to light. iIgnited clothing causes MOST of the injuries in arc flash. One DuPont internal study indicated it contributes to 80% of the injuries in electrical incidents. This was not an electrical worker but the story enlightens us to be sure we use flame resistant, arc rated clothing. It makes a huge difference.
Anyone have any calculations for DC Arc Flash faults yet?
The new NFPA 70E standard has several options. It is coming out in a Report on Proposals (final in 2012) which will have the suggested changes.
Several papers have been published on this now and they are leading us toward the idea that DC can do about 1.2-1.3 more than a 3 phase fault in AC.
The hardest part is fault current calculations for the DC source.
I’m on the NFPA 70E DC Arc Flash Taskforce and I offered a proposal to add DC to the tables. This was revised by our taskforce and entered into the record. This will be published in June or July for public comment. I’ll have a link to it on the blog and in the newsletter when it is out.
Hugh Hoagland