3% and 5% voltage drop

[480 Live]

The present code strongly suggest that the feeder and branch circuit have a 3% voltage drop, but I thought many years ago it was required that the maximum voltage drop for a feeder and a branch circuit was 3% and the total could not exceed 5%. Anyone remember when this went from shall to should?

Thanks

 

[BAHTAH]

Voltage Drop

Voltage Drop

The present code strongly suggest that the feeder and branch circuit have a 3% voltage drop, but I thought many years ago it was required that the maximum voltage drop for a feeder and a branch circuit was 3% and the total could not exceed 5%. Anyone remember when this went from shall to should?

Thanks

I don't see any change. 210.19(a) FPN Branch 3% and 215.2(a)FPN Branch and Feeder combined max 5%. Split it how you will. Voltage percentages and fine print notess are not a code requirements although they are good practice. I like to hold feeders to around 2% max to allow for additional loading in the future for branch circuits but thats just me.

 

[ron]

I'm not familiar with the change you mention in the NEC, but I understand that some enegy codes have voltage drop requirements that are mandatory.

 

[mayanees]

The present code strongly suggest that the feeder and branch circuit have a 3% voltage drop, but I thought many years ago it was required that the maximum voltage drop for a feeder and a branch circuit was 3% and the total could not exceed 5%. Anyone remember when this went from shall to should?

Thanks

I have an 1897 Incandescent Wring Handbook which originally came out a little earlier. The first revision is the addition of the 3% 5% rule. I think it says 3% to the closets and 5% total to the loads. Way back in 1897 they figured that out!

John M