OSHA Standards for General Industry question

[travish]

2007 version of The OSHA Standards for General Industry, Section on Mechanical Power Press 1910.217(b)(8)(iv) "All a.c. control circuits and solenoid valve coils shall be powered by not more than a nominal 120volt a.c. supply obtained from a transformer with an isolated secondary"

Why would they care weather or not the xformer secondary is grounded or not? I have noticed on alot of older punch presses there is a "Grounded" light on the press to let you know if one leg is grounded,but I don't understand why they want it isolated?

thanks

 

[krisinjersey]

It says "isolated secondary" not grounded.

 

[jim dungar]

Isolated, as in a standard two winding transformer. The intent is to prohibit auto-transformers.

 

[travish]

I see, that makes better sense. I guess I read Isolated, and was thinking Ungrounded, but you are correct they are not the same thing

Thanks