Author Topic: How many fluorescent light fixtures safely allowed on outlet (32Watt)?  (Read 8467 times)

kamas

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How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« on: February 14, 2016, 07:34:44 PM »
How many of these 32 watt fluorescent light fixtures are you allowed to safely plug into a standard outlet of a home? Can you plug 8 of these into the same outlet safely?

this is the light fixture, it comes with a plug so you can plug it in directly to the wall.

http://www.homedepot.com/p/Commercial-Electric-Rugged-2-Lamp-Hanging-Fluorescent-Gray-ShopLight-CESL402-27/203725928
(
Commercial Electric
Model # CESL402-27
Internet # 203725928
Store SKU # 201627
Rugged 2-Lamp Hanging Fluorescent Gray ShopLight )

Amps  = Watt/ volts

So the outlet in the house uses 110 volts right? then that means

amps = 32 watt/ 110 volts = 0.29 AMPs?

Is that the correct formula for amps used by the appliance?

bobechs

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #1 on: February 14, 2016, 08:47:59 PM »
The circuit behind your outlet is rated at a maximum of either 15 or 20 amps.  Taking the lower rating, and the safe load of 80% of max, that's 12 amps X 120 volts = 1440 watts.

32 watts X 45 =1440.  So, you could load that circuit (not just the single outlet) with 45 of those suckers- and nothing else on the circuit.  Assuming your hardware (lamp wire gauge, power strips, or what have you) downstream of the outlet will support a draw of 1440 watts, of course.

Edit: I looked at the product you linked to, and that's not a 32 watt appliance.  Each tube is 32 watts.  With two of those tubes in operation it's a 64 watt appliance, so the maximum on a circuit is half what I stated above.

« Last Edit: February 14, 2016, 09:07:48 PM by bobechs »

BudgetSlasher

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #2 on: February 15, 2016, 10:20:01 AM »
Yes you should be able to put 8 of those onto a single circuit and depending on what else you is on the circuit you will will not overload the circuit. And most outlets are rated for 15-amps so you also will not overload the outlet.

What are you trying to accomplish? Some member her might have some additional suggests or guidance.

If you buy 8 of those and then buy 2 bulbs for each you are looking at (8*2)*3000 or 3200 lumen . . .

48000 to 51200 lumen is a lot of light and I do mean a lot, especially to all be tethered to an outlet by 5-foot cords.

For example my ~600 sqft workshop has 13 60w equivalent LEDs (~800 lumen) for a total of 10,400 and I have not problems or need of task lighting

my basement (which I am embarrassed to say is ~1500 sqft) has 18 of the same bulbs for 14,000 lumens and I may add a couple only to address shadows cast over the laundry area and aimed at the back of the shelves that hold the canned goods.

my unconditioned attic (~875 sqft) has 10 for 8,000 lumen and that is plenty for an attic

DarinC

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #3 on: February 15, 2016, 12:22:14 PM »
Could these all be to be switched on at the same time? If so, it's a good idea to use start-up current to determine the number of tubes per circuit, and that depends on the ballast you're using.

Have you considered LEDs? I'd give a couple a shot and go from there if you like them. You can get the tubes+non-shunted holders for ~\$10+ and it takes maybe 10 minutes per fixture to convert. It's easy to switch back as long as you keep the ballasts/shunted holder. On paper, both output the same lumens/W, but to me the amount of light a 32W Fluorescent provides is only a smidge more than what an 18W LED provides because the LED is directional. The LED should also last ~2.5 times longer, but only time will really tell.

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #4 on: February 15, 2016, 12:46:09 PM »

Amps  = Watt/ volts

So the outlet in the house uses 110 volts right? then that means

amps = 32 watt/ 110 volts = 0.29 AMPs?

Is that the correct formula for amps used by the appliance?

No that's not how it works with fluorescent fixtures. The actual amp draw is listed on the ballast, and is much higher than your calculations. This is due to the fact that, unlike incandescent lighting, the ballast is acting as a transformer and using energy to do so. I did a quick search and found ballasts listed as a  0.9 Amp draw for that application. Therefore, on a completely unloaded fifteen amp circuit, you could run thirteen of the fixtures.

soupcxan

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #5 on: February 15, 2016, 03:28:53 PM »
If you need 8 of these you need to consider a direct wired wall switched solution. I would get tired real fast of pulling 8 pull cords to turn the lights on, and then pulling 8 cords to turn them all off every time I wanted to use the room.

I would also be nervous about putting that much current through a long extension cord on a long-term basis.
« Last Edit: February 15, 2016, 03:30:39 PM by soupcxan »

BudgetSlasher

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #6 on: February 16, 2016, 03:07:29 PM »
If you need 8 of these you need to consider a direct wired wall switched solution. I would get tired real fast of pulling 8 pull cords to turn the lights on, and then pulling 8 cords to turn them all off every time I wanted to use the room.

I would also be nervous about putting that much current through a long extension cord on a long-term basis.

I generally agree with you that a wired setup with a switch would be the nicest long-term setup.

That being said, a relatively cheap power strip will handle 15 amps and allow one to turn them all on or off at the same time. Also I would have no problem running them on appropriately sized extension cords a 12-gauge extension cord will handle 15 amps (rated amount for a normal outlet and many outlet circuits) all day every day. Which is probably the cheaper and easier setup if you are doing something seasonally with that much light (maybe he is starting all the seedlings for his garden this time of year).

Jack

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #7 on: February 16, 2016, 03:24:51 PM »
Have you considered LEDs?

I second this. Instead of getting those flourescent fixtures from Home Depot, get these LED ones from Costco (sorry, I couldn't find a costco.com link). They're currently \$30 each at my local Costco.

(On a related note, is hard-wiring a light that's designed to be plugged into an outlet kosher according to the NEC and/or generally safe? If not, does anybody know of a similar lumens-per-dollar LED fixture that is designed to be hard-wired?)

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #8 on: February 17, 2016, 07:42:59 AM »
sue you can hard wire it in, but why? You would need to use a whole lot more time, material and expense, compared to adding a box and receptacle to use the factory cord. Once you jump up a notch, past the \$10 crap "shop lights",  fixtures no longer come with cords, and they are designed to be hard wired either from the back, or ends of the metal housing.

Jack

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #9 on: February 17, 2016, 08:18:35 AM »
sue you can hard wire it in, but why? You would need to use a whole lot more time, material and expense, compared to adding a box and receptacle to use the factory cord. Once you jump up a notch, past the \$10 crap "shop lights",  fixtures no longer come with cords, and they are designed to be hard wired either from the back, or ends of the metal housing.

Are you suggesting those Costco LED ones are "crap?" If so, what's sub-standard about them?

As for why hard-wire, it's obviously better than using outlets for a permanent installation (and I don't see why it'd be any more expensive either).

I didn't mention it explicitly before because I didn't want to hijack the thread, but I got a bunch of these for my basement (which was lit by exactly two single bare bulbs for an 800 ft2 space with almost no windows... it has a couple more, but when the house was rewired 15 years ago the wiring to them was cut and not replaced). The Costco LEDs are currently jury-rigged to a power strip hanging off the single, solitary receptacle, but I'd like to wire them up to the switch by the door (with romex running properly through holes drilled in the joists, rather than extension cords draped across the top of the ducts and pipes).

I guess having outlets in the ceiling wouldn't be that weird for a basement, and might even be convenient for things like powering a table saw in the middle of the space. Still, it just doesn't seem right to me.

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #10 on: February 17, 2016, 02:13:50 PM »
sue you can hard wire it in, but why? You would need to use a whole lot more time, material and expense, compared to adding a box and receptacle to use the factory cord. Once you jump up a notch, past the \$10 crap "shop lights",  fixtures no longer come with cords, and they are designed to be hard wired either from the back, or ends of the metal housing.

Are you suggesting those Costco LED ones are "crap?" If so, what's sub-standard about them?

Did my comment refer to a \$10 crap shop light?  Or a \$30 LED fixture?  I know little of the specific Costco product, but I do know that inexpensive LED fixtures tend to have a high failure rate, especially if they are low cost, China sourced, and have multiple LEDS. They tend to have individual diodes fail, which is far from catastrophic.

As for why hard-wire, it's obviously better than using outlets for a permanent installation (and I don't see why it'd be any more expensive either).

Nothing is obvious. I wired countless garages with a series of switched receptacles on the ceilings, for use with the \$10 shop lights. When a fixture fails, the customer can then unplug the thing, toss it in the trash, and replace it for less than cost of a new ballast. Given that a hard wired one would typically take a \$150-200 service call to replace the ballast, for most homeowners, I find it to be a better solution.

I didn't mention it explicitly before because I didn't want to hijack the thread, but I got a bunch of these for my basement (which was lit by exactly two single bare bulbs for an 800 ft2 space with almost no windows... it has a couple more, but when the house was rewired 15 years ago the wiring to them was cut and not replaced). The Costco LEDs are currently jury-rigged to a power strip hanging off the single, solitary receptacle, but I'd like to wire them up to the switch by the door (with romex running properly through holes drilled in the joists, rather than extension cords draped across the top of the ducts and pipes).

I guess having outlets in the ceiling wouldn't be that weird for a basement, and might even be convenient for things like powering a table saw in the middle of the space. Still, it just doesn't seem right to me.

Outlets in the ceiling are perfectly legal an a lot more common than you would imagine. I do find that many tools like router tables and table saws tend to be a pain in the ass when wired from above. It seems like a slick idea until you are trying to rip a long piece of wood and you get it caught in the cord, or the cord gets in your way as you maneuver around the work table.

BudgetSlasher

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Re: How many fluorescent light fixtures safely allowed on outlet (32Watt)?
« Reply #11 on: February 17, 2016, 06:55:54 PM »
sue you can hard wire it in, but why? You would need to use a whole lot more time, material and expense, compared to adding a box and receptacle to use the factory cord. Once you jump up a notch, past the \$10 crap "shop lights",  fixtures no longer come with cords, and they are designed to be hard wired either from the back, or ends of the metal housing.

As for why hard-wire, it's obviously better than using outlets for a permanent installation (and I don't see why it'd be any more expensive either).

Perhaps it is more expensive, because the original question was how many of these can be connected to a single existing outlet; obviously that means there is some sort of splitter/power strip involved, maybe already laying around waiting for a use.

Now compare that to a cost of a switch (and box and faceplate) and multiple power boxes (don't want too many conductors in any one box), the romex between the between the boxes. Don't forget all the little things, wire staples, box covers, wire nuts and the like).

Of course all of that assume access such as a basement and not a finished room with no easy way to install new wiring.

I would also hardware for a permanent setup, but for temporary or seasonal . . . I'd rely on what is already there.

Maybe the thread starter will return and give us more information on what and where they are attempting to accomplish this.