seperately derived system

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erfitz1208

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Location
St. Petersburg, FL
we recently did a lighting job where we removed ballasts and lamps that were 277volt. we installed a stepdown transformer to change over to 120 volt LED lights. we tied the ground wire and neutrals together on the load side. as we were told a transformer load side is a seperated derived system and needed to be re-grounded. were we correct in doing that?? what is the correct way to do this?? thank you
 
Couple of questions,

1 Did you run a new GEC ?

2 Did you install a Main Bonding Jumper ?

3 Was there a JW on the job with you ?
 
thanks

thanks

thanks Pierre for the help that is the answer i was looking for....benaround-i am a 1st yr appr. i was working w a journeyman on the job who seemed unsure of his decision. whats a GEC? thnx again
 
GEC= GROUNDING ELECTRODE CONDUCTOR, sorry, my shift button got stuck. A conductor

from the XO of the transformer, or , the neutral bar in the new panel, to the buildings'

steel frame ( in most cases ) or a grounding electrode close by if no building steel is

available as an electrode. A system bonding jumper from XO to EG terminal bar is also

very much needed. It's good to see you asking questions about this, people can get hurt

if not installed right.
 
The secondary side of a transformer is a separately derived system. You would have to install a system bonding jumper. NEC 250.30 gives you all the information you need. The system bonding jumper can either be connected at the source(transformer) or the first system disconnect. But the grounding electrode conductor must be at the same location where the system bonding jumper connects to the neutral.
 
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