Arc Flash

[KP2]

Hello all,

I was wondering if I need to wear arc flash PPE if I was going to use a voltage tester to test 208 volt circuit that is feed with a arc flash breaker.

I would only be testing!!!!!

Thanks
Kevin

 

[zog]

Yes you do, unless you are working outside the arc flash boundary (If one has been calculated).

What is an Arc Flash breaker?????

 

[charlie b]

By any chance are you confusing the notion of "arc flash" with that of the "arc fault circuit interrupter"?

 

[KP2]

OOOPPSSS. I meant Arc Fault.
Sorry

 

[KP2]

I figured I would still need protection.
Thanks Guys.

 

[jghrist]

IEEE Std 1584-2002, IEEE Guide for Performing Arc-flash Hazard Calculations, says that equipment below 240 V neeed not be considered if it is served by a transformer smaller than 125 kVA. This exclusion was explicit in NFPA 70E-2009, but in NFPA 70E-2012, it is only included by reference to IEEE 1584 in Informational Note No. 5 of 130.5.

 

[charlie b]

. . . equipment below 240 V neeed not be considered if it is served by a transformer smaller than 125 kVA.

It need not be considered in the process of performing arc flash calculations. That is because the calculation will always show the arc flash energy to be within the lowest classification. You still need PPE, but you only need the lowest level of PPE.

 

[KP2]

Thanks
That means it is 4 cal/cm? Long Sleeve shirt, with natural fiber pants, (for now, I understand this will change next year)
hearing protection
Voltage rated gloves
Eye Protection
work boots
hard hat
Voltage rated tools.

 

[jghrist]

4 cal/cm? is HRC (Hazard/Risk Category) 1 which would require arc-rated clothing. HRC 0 requires nonmelting or natural fiber long sleeve shirt and pants (4.5 oz/yd?). There is no incident energy associated with HRC 0, but 1.2 cal/cm? would be implied as the upper limit.

NFPA 70E doesn't really say to use HRC 0 under the 208 V, 125 kVA exception, only that an arc flash hazard analysis is not required. I would assume that you would then go by the task tables which have HRC 0 minimum, but HRC 1 for voltage testing.

Assuming HRC 0 could also be justified because the basis for the exception is IEEE 1584 which says that

The arc-flash hazard need only be considered for large 208 V systems: systems fed by transformers smaller than 125 kVA should not be a concern.

In fact, you could interprete this to mean that there is no hazard and PPE requirements are for where hazards are present. All in all, I think HRC 0 PPE would be acceptable, but then I'm not an OSHA inspector investigating an accident.

 

[KP2]

Ok - this is my situation. I am a teacher at a trade school and our students have been questioing the ppe they are to wear in the lab during projects. We have times when we test the circuits to trouble shoot. We never replace or come in contact with live parts except to test. I was trying to understand why schools do not enforce ppe. I am going to college for engineering and even there we are using voltages over 50 volts ac & dc without even being told we could get hurt. Is ther an isolation transformer that can be used or something I'm missing.

 

[zog]

Sad the schools are not even teaching right when it comes to safety and procedures. If I were you, I would do an arc flash study on the lab you teach in, you could even make the study a project for your engineering class, extra credit maybe. Most likely, when you do the actual study, there will be a very small hazard and HRC 0 +rubber gloves will be enough, but you can't make that assumption until you do the analysis.