Obvious there are no switching devices. Do they still require labels?
Thank you in advance.

Yes, we do label transformers. The old exception for below 125 kVA and 240 volts was deleted. We now label almost every transformer. It's a little extra effort, but if you are doing a full arc flash hazard analysis, you still need to capture the impedance etc anyway to calculate the hazard and fault currnt for downstream devices so why not label the transformer? Here is how I do this, suppose you have 10 or 20 transformers at your site, the extra cost to label them is nothing against the cost of a single accident.

I agree on the disconnects and the transformer.

I'm interested in Jim's take on this.

From 1584.1:

NOTE—Transformers (utility company and customer owned) are required as information to perform an arc-flash
study; however, even though transformers do present an arc-flash hazard, they are not generally serviced while
energized and thus they are not generally labeled.

"From 1584.1:

NOTE—Transformers (utility company and customer owned) are required as information to perform an arc-flash
study; however, even though transformers do present an arc-flash hazard, they are not generally serviced while
energized and thus they are not generally labeled."

Not sure I agree with this statement. Doors are opened for inspection, e.g. data collection, etc. and companies perform oil sampling all of the time while energized.

Good topic to discuss,

Mike

And there is still the paradox:
Disconnect the transformer for de-energized work, then test to ensure de-energized state while the unit is still assumed to be energized.
The label will help to ensure proper PPE during the voltage test.

I have on labelled some transformers. The substation type (separate doors on opposite sides )with two different labels. The small dry types typically not. The pad mounts (green boxes) haven't set up a practice as one side is a lower hazard then the other but at a much higher voltage but are on two adjacent doors..

As for junction boxes, if it has a power distribution block yes, but if it is just a pull point where the cables are spliced to the cables leaving probably not. I guess when it shows up as a node in the arc flash software, then it get a label.

There are many instances when you are troubleshooting a cct where you take a voltage reading off the secondary of a low voltage dry transformer to confirm your correct supply under load and non load conditions. You also want to measure the energy loss of older dry type transformers as they can become a passive energy drain with age. This also has to be done energized. Since a transformer could be in your system for decades you should label them and get it over with. Same for high energy junction boxes. Doing these shows good safety leadership and walking the walk to your technicians.

Dave Smith
Canada Training Group

NOTE—Transformers (utility company and customer owned) are required as information to perform an arc-flash
study; however, even though transformers do present an arc-flash hazard, they are not generally serviced while
energized and thus they are not generally labeled.

I understand the above statement, but again, if you are performing a full study, the added cost for a label is nothing when compared with the cost of a single arc flash accident.