Load Diversity

jbelectric777

Has anyone ever used the Annex B version of ampacity adjustment ? I specified ten gauge for a job that requires 30 current carrying conductors in a two inch conduit, another electrician wants to use twelve gauge and the load diversity table. I know Mike Holt has a proposal for 2008 to just delete it or make it something to be used in very rare situations and only then used by a design professional. I de-rated #10 to 45% of 35A (310-16) The other guy says we can use the load diversity table but I disagree because out of the same conduit will be continuous lighting and three phase motors which will operate intermittent. What say you ?

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" For all those whom beleive in Telekinesis, Raise my Right Arm"

mdshunk

When you start talking about load diversity, in my opinion, you're getting into an engineer's territory. As an electrician, I never consider it. A bit over my head, to be honest. The annex is not enforcable code text, so you need to get your inspector to buy off on the load diversity idea too. Not so easy, when there's no PE saying he's run the numbers and it will be fine.

jbelectric777

exactly, it might be ok if a PE submitted for a plan review and seal pressed with his calculations, but not an electrician or even licensed contractor because your right, and it's over my head too. I mean I'm sure if we wanted to really get into the numbers and see what they are talking about we could figure it out, but why, we already have an enforceable table thats not over our heads.

__________________
" For all those whom beleive in Telekinesis, Raise my Right Arm"

mdshunk

I think you need to make it clear to the customer that the other contractor is walking a thin, dangerous line. Let them know that he's trying to save pennies a foot for wire, and if things fail, it will bring the whole process to a screeching halt by trying to save mere pennies per foot. Not worth it. Your method will work. His method might work, but why take the risk? Tell them that.