TK, Cobraguy, Labman, KISS

Okay, I now have a nine volume set of current books ranging from simple wiring to the NEC.

I also sound some U.S. Navy BPARS manuals and theoretical engineering books from when I went to Internal Corporate electrical schools. Not to mmention product specific manuals that I still have squirled away.

I realize my brain capacity is turning to weak jelly but I swear, trying to follow the NEC code to size a conductor for a load is like falling into a black hole for me.

It's like Geometry for me. A flat out blank sheet of paper, staring back at me.

I understand that I have to consider line voltage drops over long runs and the need to compensate with a lower level of resistance, but I can't just get it working for me.

Here's a test case I built, 120/240 VAC 200 Amp feeder service to main panel.

I want a standard sized office, (want but will never build):

Requirements:

120/240 supply 150 Amp (?).

(2 ea.) 36" florscents overhead down the center of the room.
(25 ea. 120 outlets)
(1 ea. baseboard heater) Wall operated thermostat.
(2 ea. sets of outside safety lights - covering corner accesses)

Outlets:
To be used for general low appliance loads. Computer, Per-ifs.) and so on.

Now here's my question. I'm the electrician trying to bid this job. I have an NEC 2005 Study Guide and a NEC 2008 Code book) LRA uses the 2003 version of NEC Code.

Where do I start? Also, I do not want anyone to just punch answers into this for me. I'd much rather you point me to where I can find the information and then see if I can get it accurately from the books to the responses. Anyone game?

The most I use is the NEC handbook for the details of all the various variables, demand factors, minimums and maximums, but to add something often overlooked for those looking to learn the field, almost all product catalogs.

Here is where design can be learned at the basic level, not the user but the design, as they will show the very basic design, and usually have the relevant codes and installation methods for that line or product.

Unfortunately, I think the paper catalogs are so much better than the website ones, and web-based catalogs... suck.

I have learned so much from these, from application to how to troubleshoot the product.

Instructions,. product instructions, OK stop laughing... yes I read instructions. Amazing what can be learned from the instructions for even basic materials. How many here have read the box for Romex? Or wallcases?


Some products, like Honeywell , well use to, publish handbooks for the product line. Here is where I collected most burner controls, or relay logic, ladder diagrams, even basic circuit design.

To bid a job really requires a good understanding of actually building the circuit and system, and know how to use the code, to design the entire system and to take advantage of the most practical methods and products, and nowadays, most economical, system, and include for future growth capacity.

One important factor is to be efficient. Of course, there are minutes and max, and "codes", that are more obscure, such as the Dark Sky Initiative, Leeds, Ash Rae (sic?) (Product catalogs help here too), and other regional and local ordinances.

Product knowledge, and knowing what is new and coming, help with design.

Design is also learned from plans and specs from various design firms that are encountered over the years.

Knowing the code helps with design , by telling you where something can be used, or more importantly, where not allowed. This helps with direction of the design. Plastic? Metal? Indoor? Outdoor?

To bid the job you need to simply do a takeoff of the bill of materials, the more accurate the bill, the more accurate the bid,and then price each piece and assign a labor unit to install it, total it, add for various markup, taxes, job conditions, etc. to arrive at a lump total.

To do this, a good working knowledge of code, design, and products is needed, equally. This can be a challenge to arrive at a decent design, and price. Too much over engineering, due to guessing or lack of knowledge (AKA Safety Factor), will kill a bid, or the bidder.

Donf:

What voltage would you use to base your % loss on and why?

Good question.



Donf:

What voltage would you use to base your % loss on and why?


Don?

If not planning on doing work with the NAVY, I would stick to NEC,
Good info and questions above. I would and did get Mike Holts "Practice Exams for Journeyman Electricians" and "Practice Exams for the Master Electrician" Plus you will need the code book for Conduit size, Circular Mils, etc. To add to TK's:
Mike Holt (http://www.mikeholt.com/technical.php?id=nec/unformatted/conductor&type=u&title=Conductor%20Sizing%20(11-19-99))

Did anyone miss that this question is from more than a year ago?

Don