Hi everyone. Need a few opinions about labeling switchgear. We are thinking of labeling the two mains separately since their incident energy is dependent on the upstream device. We would have a label for each distribution section based on the setting of the 2 mains. We are thinking of putting labels on the back but this might be overkill. Does this make sense?

The tie is causing us to question ourselves. If someone is working in this area live with the tie racked out, removed or open and the 2 mains closed (normal condition for us), won't the fault current be coming from both mains and meet in the middle for a much larger fault current if something really rare happens? This is probably a very very remote chance but it seems everyone is playing (overly?) safe.

Thanks!

I can't speak to the specifics of your site but will offer a general opinion.

1) If at all possible rate the whole switchgear lineup to the same rating. This allows for the least complexity. If you can do this, I would put the labels at the top of each section and one on each back door.

2) If #1 is not possible then do as you indicate. I would probably then put labels on each cubicle. I think that an average person may walk up to the gear, read one label and assume it is for the lineup. So you need more labelling under this condition, and it also needs to be covered in training that switchgear may have multiple ratings.

3) As for the multiple source tie. If the tie is normally closed, then you need to include both sources in the analysis. If you haven't, then I assume its because having the tie closed is not normal. You need to cover this special condition in your training, and make it an exception to routine work that requires a permit. You should analize that condition and know what the new IE is for that condition. You can also put on your label next to the IE value 'Tie Open' or some seperate label. If the condition is restricted to just your employees and they are trained to the condition, I wouldn't say more labelling was a must do.

Multiple conditions are tricky. Best is to design for the worse case if possible, but it not possible, then it has to be covered in training or added labelling.