ECN Forum Forums General Topics of the Trade General Discussion Area # of conductors in conduit

Scott, we were on the same page though.

Roger

Ditto on the Plan Review & Approvals. Between the Architects and the EE/PE's sometimes it can really get funny!!!!

LMAO a few weeks back....." did you de-rate for # of conductors?"; "how about ambient temp?"...long pause then reply 'did I sign & seal the drawings?' My reply, "well that depends; want them back?"

Sometimes, not always.

Hence, we do Plan Review!

John

I guess this is why we have to rewrite the code every 3 years. If common sense doesn't count for anything I guess we deserve it.
It is clear that if 2 wires carrying 20a are OK in this pipe 11 wires sharing the SAME 20 amps between them will run cooler.

Perhaps they feel an exception for this fairly rare problem would just add further confusion to an area that already causes confusion.

The answer is fairly easy, run a second raceway.

How is determining the derating factor and ampacity of 11 cables on a 20A circuit NOT related to determining ampacity, the one singular section of code where engineers are explicitely allowed to deviate?

At any rate, NEC is not the code, NEC is just the code invoked by the locality. The locality always has the final say, and the AHJ will grant engineers a lot more slack than they will for if they have to accept the liability themself. In my area, certain inspections can we waived completely if an engineer stamps a letter attesting to proper design and installation. Plan reviews are still important; I know it's hard to believe and very rarely happens, but engineers can make mistakes too!

Edit: NEC 90.2(C) and 90.4 states explicitely that AHJs can allow deviations.

[This message has been edited by SteveFehr (edited 02-07-2007).]

Steve, just out of curiosity, do you carry any type of liability or E and O insurance?

Roger

BTW, VA addopted the 2002 NEC in November of 05 I believe, so if that is the case it is in fact the code.

Roger

[This message has been edited by Roger (edited 02-07-2007).]

"There are very few situations that would fall under 'engineering supervision'."

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While the NEC contains the phrase "engineering supervision", the national building codes do not.

The national building codes including the NEC portion are simply a set of prescriptions.

You either follow the prescription or you have an engineer deviate from the prescription and stamp the plans.

Conduit fill is a prescription. An engineer can deviate from it.

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I think the above shows the legal reasoning that allows an engineer to practice engineering.

Roger, VA adopted IBC which invokes NEC by reference. And my locality adopted the VA uniform building code. There's a good deal of verbage on top of it all that I've never really gone into, I've never had a reason to, I only work on Federal projects and I'm the AHJ.

I just got my PE license 2 weeks ago, so I haven't actually stamped anything yet I don't plan to any time soon, because of liability but I'm sure proud to have those stamps! If nothing else, it's quite a confidence boost. I don't plan on getting E&O insurance because all my work is federal, and I don't actually have to stamp anything. If I start doing work on the side, I'll have to get insurance, but MAN it's expensive, even the cheapest policies are several thousand dollars! If I had to get insurance to work side jobs, it just wouldn't be worth it- I'm looking for niches where I can work maybe a few evenings and weekends and the occasional day off my "real" job and insurance wouldn't be required, like consulting for insurance adjustors.

[This message has been edited by SteveFehr (edited 02-07-2007).]

I've always understood the term "engineering supervision" to mean that the site had ongoing engineering oversight of the operation of the electrical system, such as you might find in a major industrial or institutional facility. And thus, that there is never "engineering supervision" of a residence or small business.

In other words, the word "supervision" implies an ongoing activity, as opposed to, say, "review", which would imply that an engineer did his calcs, stamped the drawing, and was done with it.

Any other thoughts on this?