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The Safety Brief In our podcasts we give short but valuable overviews
and insights into how contractors and safety managers
can be even more effective in protecting their workers.
In our podcasts we give short but valuable overviews and insights into how contractors and safety managers can be even more effective in protecting their workers.

Available Fault Current Labels

Available fault current is the maximum current in a short circuit. Electrical service panels must be labeled with the current, and the date it was calculated. If it changes, the label needs to be replaced with the new calculation and date.

In this podcast we review the change in the NFPA 70 National Electrical Code 2011. The code requires continually updated available fault current labels. If your service equipment labels were placed before 2011, they are in violation and need to be changed.

Available fault current labels are different from arc flash labeling. Both must be independently placed, based your facility’s situation.


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Dan Clark: Fault current. What is the Available Fault Current? It’s the current that could jump out of wiring during a short circuit. And your electrical service panels need to be labeled with it.

Hi there. I’m Dan Clark of The Safety Brief. This is where we talk about health and safety hazards in today’s demanding industrial and construction worksites.

Available_Fault_Current_Labels-Creative_Safety_Supply-250x167Are your labels for available fault current, the AFC, out of date? If they were made before 2011, they are. The 2011 NEC, the National Electrical Code, section 110.24, added a new rule on labeling service equipment, your panels and breakers at the electrical load end. You now have to post the available fault current and the date the calculation was made. And, if system changes happen, a new field marking label has to go up.

Why the change? Electricity can change. The source can change. On the utility side, if they swap out a transformer on that pole by your building, the available fault current could change. New feeder lines can make it change. Utility substation modifications can make it change. On your side, the customer side, major modifications in the electrical needs or use could change the available fault current.

Every change requires new labels with the date of the AFC calculation for your service equipment. These labels can’t be applied by the manufacturer because the calculation must be made after the system is in place.

Available_Fault_Current_Labels-Creative_Safety_Supply-250x250Also, available fault current labeling is not the same as, and not a part of, arc flash labeling. A different label needs to be created and placed for arc flash.

So stay safe. Fault currents can cause fires, electrocution, arc flash, and damage to people and property. And the labeling allows operators to know the limits of the system.

Fault currents can be caused by animals chewing through wires, overloaded wiring, water (which changes moisture levels), broken wires, or damaged wire insulation.

Facility managers should stay in close contact with utilities and be aware of any changes that could affect the available fault current. If it changes, make the new label and put it on that service equipment.

That’s all for this episode on Available Fault Current Labels. Come back for more tips and techniques on how to stay safety compliant in today’s ever-changing landscape of safety requirements. I’m Dan Clark of The Safety Brief, sponsored by Creative Safety Supply. See the website at


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