How do you label movable equipment that is 30 or 60 amps 480 volts? That can be plug in to outlets that are protected by fuse or circuit breaker.
Do you try to find the worst clearing time device?
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| Author: | H2Os [ Tue Jan 13, 2009 4:59 pm ] |
| Post subject: | How would you label secondary equipment? |
| How do you label movable equipment that is 30 or 60 amps 480 volts? That can be plug in to outlets that are protected by fuse or circuit breaker.
Do you try to find the worst clearing time device? |
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| Author: | wbd [ Tue Jan 13, 2009 7:18 pm ] |
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H2Os wrote: How do you label movable equipment that is 30 or 60 amps 480 volts? That can be plug in to outlets that are protected by fuse or circuit breaker.Do you try to find the worst clearing time device? I'm a little confused by your question. What are you trying to label? Is work done inside this equipment while it is energized or are you concerned about an arc flash while plugging the equipment in? |
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| Author: | H2Os [ Wed Jan 14, 2009 5:03 am ] |
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Working inside this equipment while it is energized. |
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| Author: | Zog [ Wed Jan 14, 2009 6:24 am ] |
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H2Os wrote: Working inside this equipment while it is energized.
Doing what? Why does it have to be energized? |
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| Author: | wbd [ Wed Jan 14, 2009 9:34 am ] |
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Obviously the AFH will be affected by where it is plugged in. Does the equipment have a local breaker or fuses inside of it for protection? I would assume so and they may be used for AFH protection depending on the physical configuration inside. Another option would be to analyze it a one specific location and that location would be the one to be used, if any internal energized work is needed on the eqpt. |
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| Author: | H2Os [ Wed Jan 14, 2009 11:12 pm ] |
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We do a lot of troubleshooting on production line equipment. Some of the equipment that comes in does not have any fuses or breaker inside for the mains. They rely on the outlet to trip for protection. I have been adding fuse protection when I can. My main concern is trying to find the worst location that it might be plug in to. There are so many different fuses and type of fuse and breaker that feed outlets. So I am trying to come up with one value for all the equipment that is feed by 30 amp 480 volts outlet, plus do the same thing with 60 amp outlets. |
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| Author: | John Perrotti [ Thu Jan 15, 2009 5:02 am ] |
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Difficulty This is the whole reason the NFPA 70E Tabular method was developed. To be general and applicable in most situations. If it is 480 V gear, if you are in it troubleshooting, label it as a 2* as long as where it is plugged into meets the clearing time and max SCA requirements. |
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| Author: | WDeanN [ Thu Jan 15, 2009 7:24 am ] |
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One solution, and it is what we are doing, although I had not thought of it in this context, is to label the plugs. Perform you calcs at all of the receptacles along with your other calculations that you should be performing. Then inplement a policy that the device plugged in will require the same PPE as the receptacle it is attached to. I'm finding that most of the 480V receptacles are Cat 1, often < 1cal, but have seen some much higher, depending on location. |
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| Author: | jghrist [ Thu Jan 15, 2009 10:34 am ] |
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John Perrotti wrote: This is the whole reason the NFPA 70E Tabular method was developed. To be general and applicable in most situations. If it is 480 V gear, if you are in it troubleshooting, label it as a 2* as long as where it is plugged into meets the clearing time and max SCA requirements.
But if you've done an arc hazard analysis and it shows a higher hazard category, don't you have to use it? Article 130.3 Exception No. 2 "shall be permitted to be used in lieu of a detailed incident energy analysis" would seem to imply this interpretation, but 130.3(B)(2) "shall be permitted to be used for the selection and use of personal and other protective equipment" would seem to imply that you have a choice. |
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| Author: | John Perrotti [ Sat Jan 17, 2009 7:02 am ] |
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Analysis If you have spent the time and money to perform a full blown analysis, in my experience, most of the time, you are in a lower HRC than the tabular method - but not always. A full one line analysis allows you to engineer a lower HRC when you find something, such as long clearing time, that drives your incident energy up. |
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