AHJ's or Engineer's call?

[nietzj]

I'm installing a 600amp distribution switch board intended for 3 phase loads. The AHJ sez to size it for non-linear loads just in case. The electrical engineer sez don't have any non-linear loads so his calculations are correct.... Who is right? If I do re-size for non-linear (future) loads do I just need a larger neutral?

 

[iwire]

I'm installing a 600amp distribution switch board intended for 3 phase loads. The AHJ sez to size it for non-linear loads just in case. The electrical engineer sez don't have any non-linear loads so his calculations are correct.... Who is right? If I do re-size for non-linear (future) loads do I just need a larger neutral?

There is no NEC requirement to size anything for the future.

I suggest pointing out 90.2(B) to the AHJ.

90.1 Purpose.

(B) Adequacy. This Code contains provisions that are considered necessary for safety. Compliance therewith and proper maintenance results in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.

It is up to the person paying for the work if they want to plan for the future or not.

 

[infinity]

I agree with Bob the AHJ is making up his own requirements.

 

[jap]

I'm installing a 600amp distribution switch board intended for 3 phase loads. The AHJ sez to size it for non-linear loads just in case. The electrical engineer sez don't have any non-linear loads so his calculations are correct.... Who is right? If I do re-size for non-linear (future) loads do I just need a larger neutral?

Is this a design of your own and your asking both for opinions?

Or

Did the Owner hire an Electrical Engineer to design the project?

If it's the latter, I don't see how the AHJ would have any say on that issue.


JAP>

 

[ron]

If I do re-size for non-linear (future) loads do I just need a larger neutral?

We have not oversized the neutral for non-linear loads in a long time. Triplin harmonics are there, but not to the extent they used to be.

Maybe the AHJ wants you to consider the grounded conductor a CCC in your ampacity calculation.

 

[iwire]

Maybe the AHJ wants you to consider the grounded conductor a CCC in your ampacity calculation.

That makes more sense however they still can't require it for loads that do not exist.

 

[nietzj]

No these are not my drawings, they were provided by a registered electrical engineer. I thought the same thing, only inspect what is being installed, who knows what's down the line if anything. My concern is referring the inspector to 90.2 (B) generally inspectors don't like this approach.