Is the practice of grounding out electrical wires on an existing panel, even when power is removed, a good idea in all cases?

This is one of the FAQs from our Electrical Safety Panel Discussion with John Kolak MS CSP, Charles Miller NEC Expert, & Bhanu Srilla CESP CMRP.

John Kolak: That's a required element for high voltage work. If you're working on high voltage systems, you don't have a choice. If you're going to take your gloves off and put your hands on it, it's got to be not only locked out, tagged out and tested, but it has to have a visible open in the system and you have to have a full set of personal protective grounds installed. So at high voltage, it's not an option, it's a requirement. If you're planning on taking your gloves off.

At a low voltage, it is very much circumstantial as to whether you're going to do it. Most low voltage systems aren't configured to accept a set of protective grounds. Usually, on things like pad mount transformers would you get an opportunity to put a set of grounds on low-voltage systems, but if that's the case, and in all cases, that's again another judgment call. If you're planning on taking your gloves off and touching the equipment, that's the real pass-fail test, isn't it? It's not whether or not you're in compliance as to whether it's safe to touch. So do I put grounds on every single time on high voltage? Yes.  Or you're going to play it hot at low voltage, if you're able to do it, it is superior to lockout and tagout all by itself, but it's not a requirement at low voltage.

Charles Miller: Where the confusion probably comes in on this is in establishing and verifying that electrical equipment is in an electrically safe work condition. There are eight steps. Step number eight is installing temporary electrical safety grounds. And when I'm teaching I'll always say to establish and verify that equipment is an electrically safe work condition. You're going to do either seven or eight steps. And just like John said, typically for low voltage, 480 volts and below, we don't install temporary electrical safety grounds. And if there's a place to do that, just like John said, you have to use temporary electrical safety grounds that are capable to handle the available fault current.

There was one factory that I worked in, they had put together their own homemade electrical safety grounding equipment, and it was almost just like a fancy pair of jumper cables. And that of course, it has to have the appropriate equipment. It has to be rated for the voltage at the available fault current. So just sticking on jumper cables, that's not a good idea.

John Kolak: The grounds not only have to be rated for fault current but also for duration, and so it's a withstand rating. It's more of an engineering function to figure that out. But it's not enough to have just rated for the amount of fault current. It's got to clear in a certain period of time, and if it's not clearing fast enough, you have to de-rate the cables, and so the engineers who do your arc flash studies would be responsible to do that if you ask them to do it, but it is not only fault current rated, it's also with duration, clearing time.


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