DIYbanter - View Single Post

Don Y[_3_]

On 9/27/2015 7:29 PM, wrote:
Sorry, I should have described more. These lights are in 4 separate
areas/rooms of the basement, on 4 separate switches. Approx 6 lights per
room/switch.

So, when the circuit trips, you're completely in the dark (?)

Usually, you try to arrange to have an alternate source of
light/power adjacent or nearby -- so you're not left in the
dark. I like to have an adjacent room on a different branch
circuit so I can let light stream in through an open doorway, etc.

Also, have you considered using LED *fixtures*? Using an incandescent
fixture with an LED replacement bulb ties you to the VA rating of
the fixture, not the bulb within. Using an LED *fixture* lets
you get away with less.

I haven't looked at the transient characteristics of LED lighting
to know what sort of "surge" they impart to the line. Presumably,
they have been designed with the characteristics of incandescent
counterparts in mind? (i.e., I wouldn't want to end up
welding the switch contacts together from some start-up surge
owing to capacitors in the lamps)

Lighting tends to be considered a continuous load so the branch
circuit must be sized at 125% of that load (said another way,
you can only "use" 80% of the rated circuit ampacity -- 16A for
a 20A branch circuit).

If you put an outlet on the same circuit, then the rules change.

You also have to look at *where* the load is located. Putting
a 16A load on the end of 100 ft of wire will result in a voltage
drop of ~6.5V at that 100 ft point. The maximum *recommended*
allowed voltage drop on a branch circuit is 5% (6V for 120VAC).
The maximum recommended drop AT THE FAR END OF A BRANCH CIRCUIT
is 3%.

[#12 AWG is considerably more annoying to work with than #14 AWG.
You might want to keep that in mind]

And, of course, *local* code requirements trump the NEC all the time.
(I lived in a place that required EMT for all runs!)

Have you cornered anyone at your local electrical supply house
to see what sort of "free advice" they offer? (which you will take
with a grain of salt...)