Others experience or help?

[la2151]

I am really interested in experiences & thoughts on tapping the main bussing using the tap rules on a older 600 amp 3ph 102/208 main switch board.? Zinsco. I have not done this type of install yet & am not going to. But a job I did bid on in a different way,the owner told me another EC is going to just tap the main bussing to get a new 200 amp 3 phase circuit to another part of the building.I do understand the code does allow this but am just asking about your thoughts? I understand he is going to install a 200 amp disconnect near the main panel. thanks.. Life is just a learning experience.

 

[Chamuit]

Pictures

Pictures

I'd love to see some pictures of this done. Heard of this before, never seen it.

 

[augie47]

It can be done. The 1st possible obstacle is that you will be altering listed equipment and often the AHJ will require a manufacturers approval and/or instructions for that but that's not possible with Zinsco so I'd check with the AHJ.
Secondly, does this panel have a main ? If not, is your additional disconnect going to take you over the six disconnect rule ? and have you done a load calculation to assure you aren't overloading the service conductors or buss.
Lastly, if it's a Zinsco panel, based on it's age and their reputation, you would be doing your customer a service by replacing it entirely.

 

[la2151]

others experience.

others experience.

thanks for the thoughts & help so far.I had the same worries about not doing it this way. I am going to try to get some pics If the other EC does this? I did have my electrical engineer do a load calc on the panel & it is ok,but i dont know if other ec did a load calc on the building.The gc that i did submit a bid to do this project asked my why i didnt bid it to just tap the mains.Told him i didnt like the idea & had possible concerns about it being done that way. will see if he does the job or not?