PPE required for 120V circuits (70E 2009)

[Electrobe]

I am tring to determine the PPE and labeling requirements for an electrical control panel fed from a 20A 120V single phase circuit that is supplied by a 37.5KVA transformer. This is using the new NFPA 70E 2009 code.

As per NFPA 70E (2009) 130.3 an arc flash hazard analysis is not required since the voltage is less then 240V, Supplied by one xfmr, and the xfmr is less than 125KVA.

Since an arc flash analysis is not needed, do you use the 130.7(C)(9) table to find the proper PPE? As per the table, working on live parts would be Hazard risk category 1. The new hazard risk catagory 1 now also requires an Arc-Rated face shield.

The new code (130.3(C)) also requires labeling these panels with either the incident energy level or PPE.

Does this mean that the electrical panel needs to be marked as Hazard risk catagory 1 and that the Flash Protection boundary would be 4FT as per 130.3(A)1? When the door is open, the employee would require a face shield if they were within 4ft of energized conductors?

Please provide some guidance because this seems like overkill.

Thanks

 

[Pierre C Belarge]

Contact either Jim Dollard or Paul Dobrowsky. They are both on 70E panel and are extremely knowledgeable about your question.

 

[infinity]

Contact either Jim Dollard or Paul Dobrowsky. They are both on 70E panel and are extremely knowledgeable about your question.

Pierre, do you have any contact info?

 

[don_resqcapt19]

If there is no arc flash hazard then you don't need arc flash PPE...just voltage PPE.

 

[zog]

I am tring to determine the PPE and labeling requirements for an electrical control panel fed from a 20A 120V single phase circuit that is supplied by a 37.5KVA transformer. This is using the new NFPA 70E 2009 code.

As per NFPA 70E (2009) 130.3 an arc flash hazard analysis is not required since the voltage is less then 240V, Supplied by one xfmr, and the xfmr is less than 125KVA.

Since an arc flash analysis is not needed, do you use the 130.7(C)(9) table to find the proper PPE? As per the table, working on live parts would be Hazard risk category 1. The new hazard risk catagory 1 now also requires an Arc-Rated face shield.

The new code (130.3(C)) also requires labeling these panels with either the incident energy level or PPE.

Does this mean that the electrical panel needs to be marked as Hazard risk catagory 1 and that the Flash Protection boundary would be 4FT as per 130.3(A)1? When the door is open, the employee would require a face shield if they were within 4ft of energized conductors?

Please provide some guidance because this seems like overkill.

Thanks

You are correct in your assumptions, either you do the analysis and label with the Ei or use the tables and label the PPE requirements.

 

[Electrobe]

Since the fault current will be less than 10KA the old 2004 code allowed a reduction of the HRC by 1 making this a HRC 0. I do not see any allowance for a reduction of 1 in the new 2009 code unless you use current limiting fuses. How do you calculate the IE for a single phase system assuming a fault current of 8KA and a standard 20A CB?

Thanks

 

[jim dungar]

...use the tables and label the PPE requirements.

What type of PPE requirement label do you invision when working with the tables? Does the label get removed after each specific task is completed and then a new one is applied?

For example: removing 600V bolted covers and then performing an IR scan, or performing 600V testing and then closing hinged doors, what lable is left on the equipment when you leave?

 

[zog]

What type of PPE requirement label do you invision when working with the tables? Does the label get removed after each specific task is completed and then a new one is applied?

For example: removing 600V bolted covers and then performing an IR scan, or performing 600V testing and then closing hinged doors, what lable is left on the equipment when you leave?

How else are you going to meet the new labeling requirements if you dont do an arc flash analysis? For 600V switchgear I would hope an analysis is done, for the OP's example IMO you should label the panel with the highest HRC in that catagory, in this case HRC 1 (Panels 240 or less)

 

[zog]

Since the fault current will be less than 10KA the old 2004 code allowed a reduction of the HRC by 1 making this a HRC 0. I do not see any allowance for a reduction of 1 in the new 2009 code unless you use current limiting fuses. How do you calculate the IE for a single phase system assuming a fault current of 8KA and a standard 20A CB?

Thanks

There are several methods to calculate Ei, look in the back of the 70E for references. You will need to know your actual available fault current and the trip curves for your breaker.

 

[jim dungar]

How else are you going to meet the new labeling requirements if you dont do an arc flash analysis? For 600V switchgear I would hope an analysis is done, for the OP's example IMO you should label the panel with the highest HRC in that catagory, in this case HRC 1 (Panels 240 or less)

That is part of my point. In your previous post you advised applying labels based on the task. How do you see the labeling requirements of NFPA70E-2009 being reconciled with the task tables? If you put on a PPE label based on the "worst case" task, would you be allowed to ignore it when performing a less risky task?

 

[zog]

If you put on a PPE label based on the "worst case" task, would you be allowed to ignore it when performing a less risky task?

Good question, if I were the safety guy at that facillity I would say no. But I would guess if you were doing a task listed in the tables as HRC 0 then that would be OK.

 

[Electrobe]

I could not find a formula that applies to 120V single phase systems in Annex D but I would assume that after the analysis this would probably be HRC 0.
It appears that we need to do the analysis on these 120V panels or default to the table and use HRC 1 which requires a big jump in PPE requirements as per the 2009 code. Wouldn't a receptable fall into this same catagory?

 

[wtucker]

70e

70e

I haven't seen the 2009 NFPA 70E, but the 2004 has this note to Table 130.7(C)(9)(a):

6. For <25 kA short circuit current available, the hazard risk category required may be reduced by one number.

You said the transformer was <125 kV, but is it < 25 kV? If so, work on energized parts drops from a Hazard/Risk Category 1 to Category 0, which Table 130.7(C)(10) indicates requires only safety glasses and non-melting (natural fiber) clothing. Category 1 requires FR clothing, safety glasses a rated hard hat, and sometimes V-rated gloves and tools (Table (c)(9)(a)), but no face shield.

 

[cschmid]

I guess I need to get the new NFPA 70E wow...

 

[zog]

I haven't seen the 2009 NFPA 70E, but the 2004 has this note to Table 130.7(C)(9)(a):

6. For <25 kA short circuit current available, the hazard risk category required may be reduced by one number.

You said the transformer was <125 kV, but is it < 25 kV? If so, work on energized parts drops from a Hazard/Risk Category 1 to Category 0, which Table 130.7(C)(10) indicates requires only safety glasses and non-melting (natural fiber) clothing. Category 1 requires FR clothing, safety glasses a rated hard hat, and sometimes V-rated gloves and tools (Table (c)(9)(a)), but no face shield.

That note has been removed in the new version, there was no evidence that it was justified and could lead to serious injuries. A facesheild has been added to the HRC 1 PPE list in the new version also.

 

[wtucker]

I just got the 2009 70E. LOTS of changes!

But new note (f) to Table 130.7(C)(9) now says, "For equipment protected by upstream current limiting fuses with arcing fault current in their current limiting range (1/2 cycle fault clearing time or less), the hazard/risk category required may be reduced by one number."

 

[richxtlc]

The only problem with current limiting fuses is that they only clear the fault in 1/2 cycle or less if the fault current is in the current limiting part of the curve, else the clearing time is a lot longer. So just installing current limiting fuses does not quarantee a fast clearing time.

 

[zog]

The only problem with current limiting fuses is that they only clear the fault in 1/2 cycle or less if the fault current is in the current limiting part of the curve, else the clearing time is a lot longer. So just installing current limiting fuses does not quarantee a fast clearing time.

Right, and it is hard to know without doing an analysis, so what is the point of that note in the tables if you need to do an analysis to figure out if it applies? I bet that note gets removed soon due to misuse, some people wont understand what it means and think they can wear reduced PPE just because they have current limiting fuses.

 

[jim dungar]

But new note (f) to Table 130.7(C)(9) now says, "For equipment protected by upstream current limiting fuses with arcing fault current in their current limiting range (1/2 cycle fault clearing time or less), the hazard/risk category required may be reduced by one number."

Looking at Low-Peak fuse current-limitation curves, from Bussmann, it looks like it takes about 5000A before their LPS-RK400 fuse enters its current limiting range, and more than 12000A for the LPS-RK600. And remember the footnote says the arcing fault current needs to be this high.

This brings us back to, how do you know you can properly apply the task tables if you haven't had a short circuit analysis performed?

 

[zog]

This would be the easiest way to figure this all out.

An accepted industry standard for those who dont do this stuff is th lowest arc that can be self sustaining on LV system is 38% of the bolted fault current. So I suppose for guestimating purposes you could use that if you know the available bolted fault current. And losts of times you need to guestimate at the available fault current by looking at the AIC ratings of the equipment and hoping the EE did it right in the first place and nothing has changed since then. So you have a breaker panel with AIC ratings of 22kA, 38% of that is 8,360A for your arcing current, not high enough to be in the LPS-RK600 current liniting range, or course you would need the fuse curves to know that.

So really that rule is nonsense, will never be properly used, it will only be misused. It is a lot easier to wear 1 higher HRC PPE than to go through all of that trouble.