Questions I've never had straight answers to

I'm a bit new to wiring circuits. I understand the basics of electricity and what is safe, but I'm having troubles getting straight
answers to some sticky code questions. I don't actually have a copy of the NEC, because that's overkill for just adding or remodeling a circuit, and it's difficult to wade through a document that size. I mostly read how-to books, pick the brains of electricians I happen upon, and use common sense. That said, yes I am having this all inspected before I actually connect any circuits to the breaker. The questions I haven't yet found answers to, including in this forum, are:
1. Is there a maximum branch-breaker:main-breaker ratio? For instance, is it up to code to have 20 circuits at 20 amps apiece on a 100 amp service? I did caculate my total need and it is below 100 amps due to the fact that I have all gas appliances (dryer, water heater, furnace, stove, etc.)
2. I have been explicitly told that I can use a 15 amp luminaire switch on a 20 amp circuit as long as the total current draw downstream from the switch does not exceed the safe limit for that switch (1440w IIRC). I believe this is safe, but is it really up-to-code?
3. I have a 20-amp circuit that I want to install a 15-amp dimmer switch on. The switch will control 450w of recessed lighting (and nothing else.) The wiring the manufacturer attached to the fixture itself is about 18awg stranded (I didn't measure it, but it's smaller than 14.) The only fixture whips I could find for them at the local HI store are 14awg. Besides that, 12awg wires would not even fit in the recessed lights, their built in junction box is too small. I believe this is safe, but is it up to code to use this configuration? I do not want to downgrade the circuit to 15-amp because I would have to break up the circuit due to load limits; the circuit also serves a 20-amp luminaire switch for a series of outlets in the ceiling (intended for beer signs, etc.) My logic is that in the case of the luminaire outlets a 20 amp switch is absolutely necessary because you cannot determine in advance the load that someone will put on the switch (what if someone plugs in an entire wood shop to those outlets, for example?)
I truly appreciate any help. advTHANKSance.
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No
Yes. Switch must be able to handle the load it controls.

Your plan is ok.

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Hi Rick,
There are some good articles in the How To books put out by Readers Digest and Time Life that should get you through your repair. I was curious....is this a home or business installation. The code is quite different for a business. You might want to get a couple of estimates to have the work done. I have found it is usually inexpensive compared to most home repairs. I had a guy do some major wiring for me between 2 buildings and under a house that took almost 3 days for about $1500 a few years back....and that included parts and flourescent fixtures! Good luck with your project....Ross

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(remove NS to use the address) 614.937.0463 voice 208.975.1011 fax
http://worthingtonengineering.com
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With out the NEC how do you know your doing things right and safely? How did you calculate your loads? Yes there is a limit to how many breakers that are after a main. It does not have anything to do with the number it has to do with the load. Ususally 200 amp residential panels are 30-42 circuit, 100-150 amp are ususally 20 circuit. Speaking of full sized breakers.

Where are you doing this? commercial, residential? Good pratices are that you use 20 amp devices on 20 amp circuits. There are exceptions that are allowed.

Do the fixtures have a UL/CSA or other listing agency that applies? Fixture whips at the local HI store. The ones I have seen are for lay-in fixtures, NOT to be installed above dry wall ceilings. I am guessing here as you stated recessed. Each fixture comes with instructions that tells you how to install the fixture properly and according to the listing of the fixture. You may be in violation in your circuitry because of fixed appliances and the installation catagory.
I highly suggest you buy a code book and start reading. You will be the better for it.

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<SNIP>

The NEC is a rather large and unwieldly document. It reads more like a legal document than a how-to. I learn by purchasing how-to books, going to HI websites, and going to NEC interpretation sites like www.homewiringandmore.com. When those don't answer my questions I humbly ask the assistance of qualified individuals who will grant me their time. I understand the importance of the NEC, but I'm hoping to get by without purchasing it. It's rather expensive; but in light of another's suggestion I may try the library.

This is for a residential primary dwelling. I'm doing this because as I'm doing basic remodeling I'm finding extremely scary code violations like soldered wires in a wall with no access or even a junction box, tripping breakers and ungrounded circuits. The situation with the recessed lights I'm describing is the most complicated thing I plan to do. If nothing else, could you help me find the section in the NEC that will describe these exceptions? My goals are to escape this electrical nightmare alive before declaring bankruptcy. I'm looking at using a 15-amp dimmer switch, for example, because they did not even sell one at the HI store. I imagine if available they're extremely expensive, just like 20A GFIs are triple the price of 15A.

The devices are UL listed. I don't have the number handy but I do know how to search UL's database by listing, so I'll try that. I believe the fixtures I purchased are intended to be used in drop ceilings or drywall according to the instructions, as long as the wiring meets the 80 degree C rule (which it does.) I will read the instructions again to be sure.
The whips came with no instructions or application guide. I sheepishly admit I did assume the whips were legal for drywall applications because they seem to be ordinary 6' lengths of armored cable with 2 THHN 14-awg wires (plus ground of course) and box clamps included on each end. Are these the style of whip you were referring to, and if so why aren't they legal for drywall?

Thank you for your time, as well as everyone else that responded.

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(remove NS to use the address) 614.937.0463 voice 208.975.1011 fax
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Try the NEC handbook. It is about the same price. It has examples, pictures and some plain english.
If you want something heavier than the 14ga, why not just get a box of 12ga type MC from the Borg and make up your own whips. Just be sure the boxes are all accessible.
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Rick Finger wrote:

No. It is determined by load

Yes. As long as it is not the only device on the circuit.

12 gauge wires are required on a 20A circuit. Depending on the application, individual "whips" to individual fixtures may be smaller.

--
jim

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