We had a project where the specs called for us to use crimp lugs on all the transformer connections. The transformer XO port had predrilled holes to be able to bolt two lugs to the XO terminal. We had parallel neutral conductors and a system bonding jumper attached to the ground bar. We attached the GEC to the ground bar. We used two straight lugs and one stacking lug. The inspector said that lug had to be a 3 barrel one piece lug. He also said that lug could not have any extra terminals say a 4 barrel using only 3 lugs. He said the parallel conductors connected to X1,X2 and X3 with the 2 crimp lugs were fine. My electrician did it the way the inspector requested to get the inspection but I can't seem to find this in the code.
Transformer X0 connection
- Thread starter ramIII
- Start date
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Your inspector is making things up. The NEC does not cover lug layout, type, or design.
Also we had a one piece ground bar. My electrician stated that sometimes we would use 2 parallel lugs bolted to the can of the transformer with 1 bolt for the ground bar. He told my electrician that would not be acceptable as the ground bar had to be one piece as well.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Can you post some photos of this transformer? I agree with the single bar as it's required by the NEC. Now many transformers come with the bar from the factory as in this photo:
Our installation that he required us to change the compression connections on the XO terminal was done several months ago so I don't have pictures. The ground bar that you show was the one used and the one we purchase now when they are not supplied with the transformer. We have been just purchasing the multi barrel logs for the XO terminal as it's not cost prohibitive but it the one case I referred to the specs had called for compression lugs. I just could not find that requirement in the code. Maybe he is interpreting 250.12 to include the XO terminal in the transformer?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Nothing wrong with that.
Not required.
Dumb statement with no bearing on the installation.
Clean surfaces? Not sure how that would apply to compression lugs. Ask for code references to all of these "violations".
Stacked lugs, this is what they're made for and often required for the X0:
I stated the wrong code reference on the grounding bar. That's the reference on preparing the surface for the ground bar. My mistake on that. What you are showing is the way we had terminated. He said that was fine for the phase connection but is stuck on that the XO connections must be on 1 bar or multi barrel lug. I'll have more discussion on this with the inspector.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Ask for a code reference. They're all bolted to the same piece of bus so how is the neutral any different than the phase conductors?
I didn't understand it either. We're doing another job with multiple transformers in the same locality and on a earlier inspection of that job he made these same statements to the electrician I have on that job.Ask for a code reference. They're all bolted to the same piece of bus so how is the neutral any different than the phase conductors?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
When you're getting negative feedback from an inspector just ask for a code reference. It's possible that this inspector is misapplying a code section which is why it makes no sense.