utlity xfmr red light

[petersonra]

What is that light for?

Someone asked me about it becasue the transformer on their property that has been there for 39 years sprouted a red light yesterday.

 

[don_resqcapt19]

I was told that older utility transformers used the red light to indicate an overload condition...I think a load greater than 150% of the transformer rating. The utilities often run their transformers in an overloaded condition and I was told they no longer use the red indicator because they get too many trouble/service calls when someone sees the red indicator on.
Look in the right column on page 2 of this document.