A couple wiring questions

[ExxWhy]

I'm wiring garage lights, 40X44 detached structure in it's own little world away from the house.

I have some 14 gauge wire I was planning to use for lighting circuits. From the panel it will go to a switch then to a row of ceiling light fixtures. From that row, I'd like to continue on to the other side of the garage to power some exterior lights. Is it permissible to run 14-3 out of the switch box to a ceiling box with the one switched wire for the lights (lets say red) and an always hot (black) wire to go on across the garage. At the ceiling box, the red and white go to the switched fixture and the black (and white) would connect to 14-2 the rest of the way across. Tie all the whites together of course.

Second dumb question. There will be 4 rows of lights and each row will need to be on it's own breaker. I'm assuming it's no issue to have 4 separate feeds going into one 4 position gang box with the 4 switches?

 

[sberry]

First question, yes, the other wire is used to switch all the time.

 

[Cmreschke]

Yes on the 4 gang with 4 feeds as well, just separate the neutrals. Tie all grounds together.

 

[Stuart in MN]

Second dumb question. There will be 4 rows of lights and each row will need to be on it's own breaker. I'm assuming it's no issue to have 4 separate feeds going into one 4 position gang box with the 4 switches?

Does each row need to be on its own breaker? How many lights are in a row, and what type?

It's not a problem to have them each on a separate breaker, but if the load is small enough to combine them it will save you time and money.

 

[ExxWhy]

Does each row need to be on its own breaker? How many lights are in a row, and what type?

It's not a problem to have them each on a separate breaker, but if the load is small enough to combine them it will save you time and money.

That's the issue my lapse in preplanning caused. I'm using 4 rows of T8 strip lights, 5 fixtures each row. I am assuming around 150 watts per fixture. (Can't find the spec for these fixtures.) 2 rows of them will be too much for a 15 amp lighting circuit. 1 row leaves enough room to handle some outside lights on the same circuit. Plan A was 2 rows per circuit and outside lights on their own circuit. Would work with a 20 amp circuit, but I have in stock 250' of 14-2 and 14-3. Labor is "free". More trouble to do this way, but does save me buying another $150 worth of wire. Just wanted to make sure it was accepted practice.

 

[Stuart in MN]

Those fixtures are 8' long, so if you have five of them in a row that's 40' - pretty much continuous fluorescents from one side of the garage to the other. Offhand that seems like a lot of fixtures - have you calculated just how many you need?

 

[cybrdyke]

That's the issue my lapse in preplanning caused. I'm using 4 rows of T8 strip lights, 5 fixtures each row. I am assuming around 150 watts per fixture. (Can't find the spec for these fixtures.) 2 rows of them will be too much for a 15 amp lighting circuit.

Each 4 lamp fixture uses 112 watts max. If the ballast is a high efficiency ballast, it could be as low as 96 watts each. Assume the worst case:
112 x 10 / 120= 9.33A. You'd be OK to use those all on a 15A circuit.
CD

 

[wyliesdiesels]

Each fixture has 4 8' bulbs? Thats a LOT of light!!

 

[ExxWhy]

Those fixtures are 8' long, so if you have five of them in a row that's 40' - pretty much continuous fluorescents from one side of the garage to the other. Offhand that seems like a lot of fixtures - have you calculated just how many you need?

Each 4 lamp fixture uses 112 watts max. If the ballast is a high efficiency ballast, it could be as low as 96 watts each. Assume the worst case:
112 x 10 / 120= 9.33A. You'd be OK to use those all on a 15A circuit.
CD

Each fixture has 4 8' bulbs? Thats a LOT of light!!

I was more or less going by some of the lighting layouts in the popular thread here. Building is 40W X 44D with 13'8" ceilings and I want/need good light.

How is the wattage figured for these strip lights to get 112? I was thinking 32 watts each bulb plus whatever the ballast uses.

The fixtures I am planning use four 4' bulbs in tandem.

 

[Stuart in MN]

You go by the amp draw of just the ballast. A ballast for 4 x 32 T8 lamps draws around 0.93 amps, 0.93 amps x 120 volts = 111.6 watts, close enough to the 112 watts cybrdyke posted.

 

[cybrdyke]

How is the wattage figured for these strip lights to get 112? I was thinking 32 watts each bulb plus whatever the ballast uses.

The bare lamp is rated 32w in a reference lab. The real world ballasts only run them at 88% full light output.

 

[ExxWhy]

These lights claim to have a high power factor ballast. Does that mean they use more power and provide more light? I'm still vague on the power factor....

 

[cybrdyke]

These lights claim to have a high power factor ballast. Does that mean they use more power and provide more light? I'm still vague on the power factor....

It can be confusing. In layman's terms:
Power factor measures the efficiency of the ballast. Almost all commercial ballasts are High Power Factor (HPF).
Ballast Factor is the measure of how much light the ballast tells the lamp to produce. More light means more watts consumed.

 

[ExxWhy]

Does that still mean I can safely assume no more than 112 watts per fixture?

 

[nadogail]

112 watts per ballast, how many ballasts per fixture?

 

[ExxWhy]

It's one ballast per fixture. I think I understand a bit better after doing a little more reading.

I'll go back to plan A and run 2 rows per circuit.Turns out I was asking the wrong question and you guys steered me to the right answer anyway.

 

[Marcm157]

Turns out I was asking the wrong question and you guys steered me to the right answer anyway.

This is exactly why I love this forum!

 

[cybrdyke]

Does that still mean I can safely assume no more than 112 watts per fixture?

Yes, that's correct.
CD