Residential General Lighting Circuits

toastermaker

Residential General Lighting Circuits

Is it becoming something of the standard to seperate lighting from receptacle circuits?

That is what we have been doing. The other day an inspector told me if we are going to seperate out the lighting from receptacles he needs to see a load calc for the lighting circuits. He said no more than the max of 15 and 20 amps for 14 and 12 awg respectivly.
I am not bothered by this even though GC and/or HO often have not chosen specifically what lights and ceiling fans they are going to use. When I am laying out circuits,I can err on the side of caution and if it isnt used now it will leave room for any future increase in the size of lighting or fans.

Doesn't this kind of negate or nulify the idea behind the number of General Lighting circuits being calculated with the 3VA per square foot method?

Where does that leave me as to deciding the required number of General Lighting circuits to be used for receptacles?

Thanks for any replys,

jproffer

Then he must have forgot the section (don't know the number) regarding 80% max continuous load, which, as I'm sure you know, leaves you 12/16 amps respectively to use.

Or am I the one who is ill-versed in the NEC?

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Jim P.

toastermaker

Thanks jproffer,

I am just learning this stuff myself. One question I have not found the answer to yet is what items (specifically) does the NEC name as continuous.

I had not thought general lighting or ceiling fans would be but I would like to know for sure.

Thanks again,

toastermaker

210.19 Conductors — Minimum Ampacity and Size.
(A) Branch Circuits Not More Than 600 Volts.
(1) General. Branch-circuit conductors shall have an ampacity not less than the maximum load to be served. Where a branch circuit supplies continuous
loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size, before the application of any adjustment or
correction factors, shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load.
Exception: Where the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the
allowable ampacity of the branch circuit conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.

Are standard 20amp breakers rated to be used at 100 percent?

Also, if a ceiling fan draws more than 1/8th horsepower then I believe that the circuit it is on might be subject to:

220.4 Maximum Loads.
The total load shall not exceed the rating of the branch circuit, and it shall not exceed the maximum loads specified in 220.4(A) through (C) under the
conditions specified therein.
(A) Motor-Operated and Combination Loads. Where a circuit supplies only motor-operated loads, Article 430 shall apply. Where a circuit supplies only
air-conditioning equipment, refrigerating equipment, or both, Article 440 shall apply. For circuits supplying loads consisting of motor-operated utilization
equipment that is fastened in place and has a motor larger than 1/8 hp in combination with other loads, the total computed load shall be based on 125 percent of the largest motor load plus the sum of the other loads.

Is that the case?
Thanks again,

Speedy Petey

Nothing!
Look at the definiton of continuous load. The key word is "expected".
Consider this. In a residence almost nothing is considered a "continuous load".


Yes, we do have to size circuits for the lighting load, but in a residence, for an inspector to actually ask for a load calc on a lighting circuit alone is absurd. This is another classic case of inspector head. Give me a break!
"Yes sir, mr inspector sir. Here is a list of every circuit in which I have lighting. Please note I have not exceeded the allowable load on each circuit. Please".

There is nothing that limits the amount of lighting on a residential branch circuit just as there is nothing that limits the number of receptacles.
We just use common sense.

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toastermaker

Thanks Speedy,

What you have said is pretty much the same as what my boss said. He told me however to never pi*s off the inspector and as just a helper I treat them the same way I do the police when ever I interact with them: Yes Sir, Thank you Sir,Yes Sir, Thank you Sir,Yes Sir, Thank you Sir.

The GC on this job had told me he had already pi*sed off this inspector pretty severely by trying to go over his head about some firewalling issues.


Any idea why ceiling fans don't come under the code constraints of 1/8 horse power motors fixed in place?

Thanks again,

mdshunk

Paddle fan motors are much less than 1/8 hp, and that constraint you speak of does not apply. Paddle fan motors are in the 75-90 watt range. A 1/8 horsepower is 93 watts, so they're just under that mark. Bath and range hoods are normally about 1/70th horsepower, unless you get a special bigger one.

toastermaker

Thanks md,
When the inspector was telling me do do a load calc for the lighting circuits he told me to use 1.5 amps for the ceiling fans.

Also, I am looking at a GE single pole 20 amp breaker but some of the writing is too small for me to read. I can make out "type THQL" but then the rest gets smaller and I can't make it out.
Would this breaker be rated for 100 percent of the listed current?

Thanks very much,

mdshunk

I'm not sure what you're asking. Any 20 amp breaker can support a 20 amp load. The code prohibits loading a breaker at 100% on a continuous basis (more than 3 hours). Rule of thumb, commercial everything is a continuous load and only load your circuits 80%. Residential, most everything is not continuous, and you may load your circuits 100%. Some resi stuff is continuous, like pool pumps.

This inspector has you thinking all wacky. Your lighting load is 3va/square foot. It doesn't matter if you do that on 2 circuits or 22 circuits, with 15 amp breakers or 20 amp breakers, or a mixture of both

steveprichard

ToastMaster,

Let me tell you a story told to me by a local master electrician who has lived through several local inspectors.

When this electrician was younger, he was also a football referee. During a referees convention and banquet dinner, the main speaker was a very well known professional NFL referee who was president of their association. When the steak dinner was being served, the baked potatoes already had the butter put in, but he wanted some more. When a waiter walked by he asked if he could have more butter. The waiter said "no, no more butter."

"But, don't you know who I am? I'm in charge of thousands of pro, semi-pro, NCAA, and UIL referees!"

The waiter said, "Don't you know who I am? I'm in charge of the butter!"

Well, inspectors are in charge of the green tags. If you have to work with one who is not reasonable, there's not much you can do. Somethimes you have to live without extra butter.

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Steve

"Keep thee thy airspeed, lest the earth rise up and smite thee!"

toastermaker

Thanks everyone,

Good ancedote steveprichard.

md, I am trying to descern what part(s) of the lighting circuits I am installing at a commercial job (goodly sized rennovation) prevent the circuit from coming under the exception to the 80% rule.

If I am even reading the correct text for the 80% rule in the first place that is. I have found 125% referenced a lot and I know 125% is the inverse of 80%.
Does 210.19 govern the commercial floresent lighting that I am dealing with (as far as the 80% rule)?


20amp single pole breaker (described as I could earlier), 12/2mc, floresent T8lights. This building used to be a funeral home and is now being made into a Real Estate sales complex.

Thanks again,

Romex-Racer

I never put bedroom lights and plugs on seperate circuits. Doing so means you'll buy twice as many AFCIs

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