Service upgrade

[haywire]

Not sure about new code requirements for meter main upgrades. It's 100 amp zinsco panel 15 circuits upgrading to 125 amp am I right with a #3 thhn and 1 1/2" riser?

 

[Dsg319]

Not sure about new code requirements for meter main upgrades. It's 100 amp zinsco panel 15 circuits upgrading to 125 amp am I right with a #3 thhn and 1 1/2" riser?

I don’t believe so. #3 Thhn copper has an ampacity of 100amperes.

You have a 125ampere OCPD (service disconnect)

Your conductors need be at least 83% of the service size.

125 x 83%= 103.75 (you need conductors with at least this ampacity).

This is based off of 2017code, sorry I don’t have code articles to name off as I’m just going from memory. Maybe someone else will chime in.

 

[Dsg319]

The 2020NEC also brought back this chart.basically the same results of the 83% rule.

 

[haywire]

Thanks for your help. I went with #2.