circuit breaker question, electrical question

[Maximus96]

i'm looking to add florescence shop lights to my garage. i believe the breaker is 15 amps. the lights are 2 tubes of 32w each. how many fixtures can i safely install, total? i don't have that many receptacles in the garage, how many can i safely install per receptacle if i use those multi socket converter things.

i thought 15amps at 110 volts = 1650 watts, which means 25 light units, but that doesn't sound right.

thanks

 

[AlienCraft]

Originally posted by: Maximus96
i'm looking to add florescence shop lights to my garage. i believe the breaker is 15 amps. the lights are 2 tubes of 32w each. how many fixtures can i safely install, total? i don't have that many receptacles in the garage, how many can i safely install per receptacle if i use those multi socket converter things.

i thought 15amps at 110 volts = 1650 watts, which means 25 light units, but that doesn't sound right.

thanks

Don't use the bulb rating, use the nameplate rating on the fixture. By the UL symbol.

 

[Jeff7]

Take into account other things like startup currents and deviations from the label - plus the ballasts won't be 100% efficient. The tube will use 32W, but the ballast will consume more than that - hence Aliencraft's suggestion to check the label on the fixture.

I think that 25 pairs of 32W fluorescent tubes would be way more than enough, unless you've got a 5000 square foot garage that's painted flat black.

 

[futuristicmonkey]

You're not allowed to load the circuit to more than 80% of the capacity of the breaker. It gets complicated -- there are situations in which you're allowed to put a 30 amp breaker on a heating load connected with 12-gauge wiring, for example, but this is the exception, not the norm. You're only allowed to load 15-amp breakers on lighting and general-purpose loads to not more than 12 amps continuous.

Of course, questions like these are better reserved for your local electrical inspection authority -- they'll give you the answers to your questions.

 

[BigJ]

Originally posted by: futuristicmonkey
You're not allowed to load the circuit to more than 80% of the capacity of the breaker. It gets complicated -- there are situations in which you're allowed to put a 30 amp breaker on a heating load connected with 12-gauge wiring, for example, but this is the exception, not the norm. You're only allowed to load 15-amp breakers on lighting an general-purpose loads to not more than 12 amps continuous.

You absolutely can load the breaker to more than 80% of capacity. Since you're specifically talking about continuous loads though, I think Aliencraft will forgive you

For those that don't know, a continuous load is where the line is expected to be used for 3 hours or more of use.

 

[DrPizza]

I believe the national electric code limits the number of such lights that can be installed on a circuit. (likewise for outlets, etc.)

 

[BigJ]

Originally posted by: DrPizza
I believe the national electric code limits the number of such lights that can be installed on a circuit. (likewise for outlets, etc.)

For residential use:

For lighting circuit loads, you're generally limited to 80% of the capacity of the circuit (see continuous loads above). This could be as many lamps as you want as long as you stay under that limit. It gets more complicated because you have to see if they're considered to be a continuous load in your area by the AHJ.

There is no maximum limit to the number of receptacles placed on a 20A or 15A circuit in the NEC.

That's not to say that people won't use certain numbers when calculating how many lights or receptacles to install in a given area, but there's no strict limit.

 

[AlienCraft]

Originally posted by: BigJ

Originally posted by: futuristicmonkey
You're not allowed to load the circuit to more than 80% of the capacity of the breaker. It gets complicated -- there are situations in which you're allowed to put a 30 amp breaker on a heating load connected with 12-gauge wiring, for example, but this is the exception, not the norm. You're only allowed to load 15-amp breakers on lighting an general-purpose loads to not more than 12 amps continuous.

You absolutely can load the breaker to more than 80% of capacity. Since you're specifically talking about continuous loads though, I think Aliencraft will forgive you

For those that don't know, a continuous load is where the line is expected to be used for 3 hours or more of use.

LOL, I did the scooby doo "unh"when I read the futuristicmonkey's post.

I'll go along with "CALCULATE a load to 80% of breaker rating".

This question comes up when n00bs want to know how many outlets/ devices can be on a branch circuit. This is determined by a thorough examination of sections 210 & 220 of the 2005 NEC, the size of the space you are dealing with, and most importantly, the intended use of that circuit.
There is a very easy table (210.24 ) that lays it out very nicely.

As a rule of thumb for 20 amp circuits on 12 ga wire, I figure 14 duplex edison outlets. edit = That means 28 holes to plug something into.


To the OP....dude, if you're going to rig a grow room, there are better lights than Flo's. :shocked:

on the serious side.... a 15 amp circuit with modern ( 1985 or later) wire can also have 14 taps, according to table 210.24

 

[TheSiege]

look at the amperage on the ballast to get a more accurate idea

 

[BigJ]

Originally posted by: AlienCraft

on the serious side.... a 15 amp circuit with modern ( 1985 or later) wire can also have 14 taps, according to table 210.24

How do you get a maximum of 14 receptacles according to 210.24?

Looking at 210.24, the 14 is merely the minimum required conductor sizing on taps from the branch circuit.

 

[AlienCraft]

Originally posted by: BigJ

Originally posted by: AlienCraft

on the serious side.... a 15 amp circuit with modern ( 1985 or later) wire can also have 14 taps, according to table 210.24

How do you get a maximum of 14 receptacles according to 210.24?

Looking at 210.24, the 14 is merely the minimum required conductor sizing on taps from the branch circuit.

Ahhh , the wonders of interpreting code....
In the summary forTable 210.24, they speak to the number multiple outlets or receptacles/ fixture wires & cords.
It also specifies previous scetions having precedence.
Since these FLO fixtures from the OP have flexible cords, they fall under it's jurisdiction.



or not.

 

[Maximus96]

sorry i think i wasn't being clear and confused everybody. currently in my garage are 3 receptacles with two sockets each, plus a switched in-wall light bulb socket. I'm not looking to wire in additional receptacles. i'm looking to install shop lights that plug into a socket, not the kind that i need to wire myself. my problem now is only one socket is within reach in the ceiling of the garage, the garage opener took the other socket. i'm looking to take out the light bulb socket and put in a two socket receptacle in its place, landing me with a total of three sockets. so i want to see with these three available sockets, can i safely plug up to two per socket using a splitter. i'm not looking to grow anything, i just want a well lit garage.

i also have a 15amp 2 hp air compressor. i probably won't have it running with all the lights on, but in my old house (1920s) the lights would go off for a second with i run the compressor. our current house is 10 years old. i don't want to overload the circuit.

 

[AlienCraft]

Originally posted by: Maximus96
sorry i think i wasn't being clear and confused everybody. currently in my garage are 3 receptacles with two sockets each, plus a switched in-wall light bulb socket. I'm not looking to wire in additional receptacles. i'm looking to install shop lights that plug into a socket, not the kind that i need to wire myself. my problem now is only one socket is within reach in the ceiling of the garage, the garage opener took the other socket. i'm looking to take out the light bulb socket and put in a two socket receptacle in its place, landing me with a total of three sockets. so i want to see with these three available sockets, can i safely plug up to two per socket using a splitter. i'm not looking to grow anything, i just want a well lit garage.

i also have a 15amp 2 hp air compressor. i probably won't have it running with all the lights on, but in my old house (1920s) the lights would go off for a second with i run the compressor. our current house is 10 years old. i don't want to overload the circuit.

I was just pulling your leg, nothing serious meant by that.

If I understand you correctly, there is a lamp Socket ( a bulb screws into ) controlled by a switch on the wall somewhere. You wish to convert that to a duplex edison outlet (like you plug into the wall ) so you can add the twin bulb shop lights in sufficient number so as to be seen fromspace... or something like that..

 

[0roo0roo]

the confusion for me is what is a socket. screw in light bulb socket? a regular plug socket? a tube fluorescent bulb socket?
fluorescent tubes have to have a ballast thats part of the fixture. a ballast willl support either 2 or 4 tubes. it says on the thing. 32watt i assume is t8, the more efficient newer kind compared to t12.

newer electronic ballasts in t8's are more efficient. older magnetic ones wasted power. you gotta include the ballast power with the watt calculation, but newer electronic ballast use a smaller fraction of power to power the light tubes. even so, they are efficient enough that run a couple fixtures off a receptacle no problem really. 4x32w=128w+ maybe, round up a little and its still almost nothing. how many watts of light do you really need for a garage? 8 32w tubes are probably enough. maybe 10.

 

[BigJ]

Originally posted by: AlienCraft

Originally posted by: BigJ

Originally posted by: AlienCraft

on the serious side.... a 15 amp circuit with modern ( 1985 or later) wire can also have 14 taps, according to table 210.24

How do you get a maximum of 14 receptacles according to 210.24?

Looking at 210.24, the 14 is merely the minimum required conductor sizing on taps from the branch circuit.

Ahhh , the wonders of interpreting code....
In the summary forTable 210.24, they speak to the number multiple outlets or receptacles/ fixture wires & cords.
It also specifies previous scetions having precedence.
Since these FLO fixtures from the OP have flexible cords, they fall under it's jurisdiction.

or not.

I don't know, I'm just not getting it out of that.

From the 2k5 NEC,

210.24 Branch-Circuit Requirements ? Summary. The
requirements for circuits that have two or more outlets or
receptacles, other than the receptacle circuits of 210.11(C)(1)
and (C)(2), are summarized in Table 210.24. This table provides
only a summary of minimum requirements. See 210.19,
210.20, and 210.21 for the specific requirements applying to
branch circuits.

If anything, I figured you would've quoted 220.14 (I) where they give the 180va minimum for calculating, resulting in 13 receptacles for 20A circuits and 10 receptacles for 15A circuits. But as said before, that load calculation doesn't apply to residential dwellings.

 

[AlienCraft]

Originally posted by: DrPizza
I believe the national electric code limits the number of such lights that can be installed on a circuit. (likewise for outlets, etc.)

Actually, the Doctor has it right. and futureisticmonkey, too.
< cue hearald trumpets.....

According to section 210.23/A1 Cord and Plug connected Equipment not Fastened in place shall not exceed 80 % of the branch circuit ampere rating.
I would say that those lights meet that. the next thing is two whole sections on lighting circuits and luminaires. I ain't going there.

I would say that should the OP be able to open that light fixture, remove the fixture and identify the wires for hot / neutral / ground, he would be able to add a duplex outlet in proper round cover, reattach the cover plate, add one of those six banger outlet adaptors and plug six dual 48 inch shoplights without too much sparking. thumbsup;

 

[Maximus96]

Originally posted by: AlienCraft

Originally posted by: Maximus96
sorry i think i wasn't being clear and confused everybody. currently in my garage are 3 receptacles with two sockets each, plus a switched in-wall light bulb socket. I'm not looking to wire in additional receptacles. i'm looking to install shop lights that plug into a socket, not the kind that i need to wire myself. my problem now is only one socket is within reach in the ceiling of the garage, the garage opener took the other socket. i'm looking to take out the light bulb socket and put in a two socket receptacle in its place, landing me with a total of three sockets. so i want to see with these three available sockets, can i safely plug up to two per socket using a splitter. i'm not looking to grow anything, i just want a well lit garage.

i also have a 15amp 2 hp air compressor. i probably won't have it running with all the lights on, but in my old house (1920s) the lights would go off for a second with i run the compressor. our current house is 10 years old. i don't want to overload the circuit.

I was just pulling your leg, nothing serious meant by that.

If I understand you correctly, there is a lamp Socket ( a bulb screws into ) controlled by a switch on the wall somewhere. You wish to convert that to a duplex edison outlet (like you plug into the wall ) so you can add the twin bulb shop lights in sufficient number so as to be seen fromspace... or something like that..

yes! and in doing so, can i safely plug in two light fixtures in to each of the three sockets. sorry if i'm using the incorrect terms. i always understood a receptacle to be the outlet with the two electrical sockets. so in the end i will have two recptacles, with 3 sockets (garage opener took up one), trying to plug in up to 6 light fixtures. i probably won't need 6, more like 4, but want to know the limits.

also, will my compressor affect anything?

 

[BigJ]

Originally posted by: AlienCraft

Originally posted by: DrPizza
I believe the national electric code limits the number of such lights that can be installed on a circuit. (likewise for outlets, etc.)

Actually, the Doctor has it right. and futureisticmonkey, too.
< cue hearald trumpets.....

According to section 210.23/A1 Cord and Plug connected Equipment not Fastened in place shall not exceed 80 % of the branch circuit ampere rating.
I would say that those lights meet that. the next thing is two whole sections on lighting circuits and luminaires. I ain't going there.

I would say that should the OP be able to open that light fixture, remove the fixture and identify the wires for hot / neutral / ground, he would be able to add a duplex outlet in proper round cover, reattach the cover plate, add one of those six banger outlet adaptors and plug six dual 48 inch shoplights without too much sparking. thumbsup;

Looking at 210.23/A1, the exact wording is

(1) Cord-and-Plug-Connected Equipment Not Fastened in Place The rating of any
one cord-and-plug-connected utilization equipment not fastened in place shall not exceed
80 percent of the branch-circuit ampere rating.

I think the keyword with that is "one".

 

[AlienCraft]

Originally posted by: Maximus96

Originally posted by: AlienCraft

Originally posted by: Maximus96
sorry i think i wasn't being clear and confused everybody. currently in my garage are 3 receptacles with two sockets each, plus a switched in-wall light bulb socket. I'm not looking to wire in additional receptacles. i'm looking to install shop lights that plug into a socket, not the kind that i need to wire myself. my problem now is only one socket is within reach in the ceiling of the garage, the garage opener took the other socket. i'm looking to take out the light bulb socket and put in a two socket receptacle in its place, landing me with a total of three sockets. so i want to see with these three available sockets, can i safely plug up to two per socket using a splitter. i'm not looking to grow anything, i just want a well lit garage.

i also have a 15amp 2 hp air compressor. i probably won't have it running with all the lights on, but in my old house (1920s) the lights would go off for a second with i run the compressor. our current house is 10 years old. i don't want to overload the circuit.

I was just pulling your leg, nothing serious meant by that.

If I understand you correctly, there is a lamp Socket ( a bulb screws into ) controlled by a switch on the wall somewhere. You wish to convert that to a duplex edison outlet (like you plug into the wall ) so you can add the twin bulb shop lights in sufficient number so as to be seen fromspace... or something like that..

yes! and in doing so, can i safely plug in two light fixtures in to each of the three sockets. sorry if i'm using the incorrect terms. i always understood a receptacle to be the outlet with the two electrical sockets. so in the end i will have two recptacles, with 3 sockets (garage opener took up one), trying to plug in up to 6 light fixtures. i probably won't need 6, more like 4, but want to know the limits.

also, will my compressor affect anything?

See my post with step by step instructions. pretty easy conversion.
Unless you like being reminded of electron flow theory, turn off the breaker, too, as you make these changes. Any basic homewiring bookwill have the necessary information for this job as well.
If it's on the same circuit breaker the compressor may cause a brief dimming as it switches on, but shouldn't affect normal operation.

 

[AlienCraft]

Originally posted by: BigJ

Originally posted by: AlienCraft

Originally posted by: DrPizza
I believe the national electric code limits the number of such lights that can be installed on a circuit. (likewise for outlets, etc.)

Actually, the Doctor has it right. and futureisticmonkey, too.
< cue hearald trumpets.....

According to section 210.23/A1 Cord and Plug connected Equipment not Fastened in place shall not exceed 80 % of the branch circuit ampere rating.
I would say that those lights meet that. the next thing is two whole sections on lighting circuits and luminaires. I ain't going there.

I would say that should the OP be able to open that light fixture, remove the fixture and identify the wires for hot / neutral / ground, he would be able to add a duplex outlet in proper round cover, reattach the cover plate, add one of those six banger outlet adaptors and plug six dual 48 inch shoplights without too much sparking. thumbsup;

Looking at 210.23/A1, the exact wording is

(1) Cord-and-Plug-Connected Equipment Not Fastened in Place The rating of any
one cord-and-plug-connected utilization equipment not fastened in place shall not exceed
80 percent of the branch-circuit ampere rating.

I think the keyword with that is "one".

duh, you're right...itsays "any one"....
ok, i quit now,i'm tired.

reminding me why I ran screaming from that one job.......
I'm pretty sure we've answered the real question aside from this errant hijacking.

Seriously, this points out why the avreage homeowner trembles when he hears "needs inspecting" concerning a home project.

Is this a lighting circuit, a branch circuit, or what? How strictly/ loosely does his (the op) AHJ interpret?
It's enough to cause one to imbibe adult beverages to excess.

 

[Maximus96]

I removed the twist-in light bulb socket last night to have a look. its got a round electrical box behind it and have the three standard wires. looks like i can easily put in a standard electrical outlet. anybody know if a standard outlet fits into round box or do i need to remove it and put in a typical retangular box?

thanks

 

[Jugernot]

You will have to replace the box with a retrofit box. Any home center (Home Depot, lowes, etc.) will have them. 90% of the time they are plastic with little wing things on the top and bottom to hold the box in place. You may have to ghetto rig something up in order to attach it to a ceiling rafter.

 

[BigJ]

Originally posted by: Jugernot
You will have to replace the box with a retrofit box. Any home center (Home Depot, lowes, etc.) will have them. 90% of the time they are plastic with little wing things on the top and bottom to hold the box in place. You may have to ghetto rig something up in order to attach it to a ceiling rafter.

No, he won't. There are duplex receptacle octagonal box plates he'll be able to use.

Be warned, if these outlets are easily accessible, they'll have to have GFCI protection.

 

[Maximus96]

thanks guys. This new outlet will not be easily accessible, its near the ceiling of the garage and I need a latter to get to it.

 

[BigJ]

Originally posted by: Maximus96
thanks guys. This new outlet will not be easily accessible, its near the ceiling of the garage and I need a latter to get to it.

Call up the town and ask them.

You may have local amendments making the requirements for electrical work more strict.

On the national level, there is an exception for non-accessible receptacles, but your state/town may vary.