See attached Breaker panel, these are from 1964 era.
Mike, it depends if the breaker is listed for that or not. It will have the letters "SWD" . and as long as the panel cover is securely in place you do not need PPE's. However, looking at the picture it's hard to tell. you will need to hire a electrical contractor to pull the breaker to find out if it is ratted.
believe it was Shakespear who wrote, regarding time, “There is time for all things, but for a man to recover hair lost by nature, for time himself is bald, and therefore, to the ends of the Earth shall have bald followers.”
Time is a funny thing. As times change, and more and more we address the issues of electrical safety (not just from an employee or personal perspective, but also looking at equipment protection) ideas about what we consider “safe” or “acceptable” change. Thirty years ago you would not find it uncommon for most every commercial building in the country to have instructions typed on a sheet of paper next to a 120/208 panel telling the stock clerk to shut off circuit breakers 13 through 34 every night before locking up the broom closet and going home.
So what has changed? When did a circuit breaker stop being a load break switch, well the answer is not easy. Some manufacturers listed their circuit breakers (and often Motor Circuit Protectors) as load breaking switches, while others did not (remember “Listing” is something a manufacturer pays for, not something they are allowed to take credit for on their own, and some manufacturers simply choose not to pay for listings for products which, in most every way are identical to other manufacturers listed products).
Can a circuit breaker that is not listed as a load break switch fail when used as a “switch” to shut off a lighting circuit? Certainly (and, don’t be startled, so can a listed breaker, listing doesn’t guarantee that a device will not fail – it only introduces a higher degree of confidence, it’s all very complicated and better off suited for lawyers to discuss, and not electricians, in my opinion).
So, long before we talk about Arc Flash hazard potential (Arc Flash Risk Assessment) we have to answer the question of whether we should be using the circuit breaker as a “switch” in the first place – and that is not an easy question to answer.
But all this doesn’t necessarily answer your question.
First off, a 120 volt, single phase circuit would not be something that could be evaluated (as it is individually) for Ac Flash Fault characteristics as they are defined by the current technical papers available. Arc Flash, so far as it is being researched, is a three-phase phenomena (some software programs that are used to report Arc Flash Energy and Exposure values can be used on single phase systems, but check with those software suppliers for information on exactly what is being reported – the program can use the single phase values in a three phase equation, or transpose the single phase values for equivalent three phase values, in order to produce a results, but in both cases you are not getting any kind of real idea of what happens when a single phase source faults – most studies today indicate that an Arc cannot be sustained when it involves only single phase sources, and there is a significant danger associated with sustained faults).
If the breaker panel is, strictly speaking, a single phase panel, I would not identify it, by Article 130.5 (NFPA 70E, 2015), as having a potential Arc Flash hazard (this is why it has changed to a “Risk Assessment” process, giving a qualified individual the ability to determine, first, if a hazard exists, rather than get bogged down in defining a hazard that might be difficult to pin down).
If the breaker panel is a three-phase panel, but is fed by a single transformer that is less than 125kVA in size (I’m assuming the panel’s three phase voltage is 208, if it is 240, it gets a bit more difficult to determine the potential hazard) then – again I would determine that there is no Arc Flash Hazard, by citing the IEEE standard, 1584 (Low Voltage Systems, part 9.3).
In general, the more you evaluate, identify, verify, and “KNOW” your systems the better off you are in determining when a Hazard is likely, and when it is not. A Risk assessment, which takes in all these factors, can be the first step in ensuring that any decision you make about operating a single pole circuit breaker safely, is approached in what we hope is the best possible way.
Oh, and one more thing - I think Id want a full level B chemical resistant suit, in addition to Arc Flash PPE before I threw a breaker on the panel in that picture - "Yikes"
Mike, David is absolutely correct in regard to the need for an assessment of the risk involved for performing the task in question. Typical arc flash values for small single phase systems (as David pointed out) are low, however there may be the potential for other hazards. Based on the photo that you provided it is obvious that either the environment in which the panel is located or the lack of maintenance could contribute to additional hazards. As an example in the textile industry where I spent 20 years it was not uncommon for small single phase faults (and even static) to ignite cotton fiber and dust to the extent of propagating a major fire. I now work in the coal industry and have seen similar incidents ignite coal dusts.
Perform (and document) a risk assessment for each task performed on your equipment. Use a hierarchy of control method to mitigate the hazard/risk.
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