Applying NFPA 70E 130.3 Excpt No. 1

[Billgas]

NFPA 70E 130.3 exception no. 1 allows not performing an arc flash analysis on circuits <240 where fed by a single transformer rated <125 kVA.

Is there a method to visually determine the size of a single pole mounted transformer - from the ground?

What size transformers are typically used by the serving utilities when the electric service size is 120/240V 200A, or 120/240V 400A?

 

[jghrist]

Is there a method to visually determine the size of a single pole mounted transformer - from the ground?

Sometimes the rating will be stencilled on the transformer case. If not, there's no way to tell without really good binoculars to see the nameplate.

What size transformers are typically used by the serving utilities when the electric service size is 120/240V 200A, or 120/240V 400A?

Could be anywhere from 5 kVA 1Ø to 500 kVA 3Ø, depending on how many customers are served from the transformer.

 

[davidbeach]

Most utilities put labels on transformers that can be read from the ground. Often something like a transformer number and a size. Maybe more. Read the labels on a bunch of transformers in your area and see if you can pick out the size among the numbers.

 

[Zogzog]

Most people misinterpret that exception, it says a detailed arc flash analysis is not required, but you still need to use the tables, and label your equipment with the PPE required from the HRC for that equipment/task, You still need PPE, training, EEWP's, etc.....

Not doing the study and using the tables, in most cases, will result in your people wearing more PPE than they would if an actual analysis was done. That means more PPE expense, upkeep, and difficutly working while wearing it.