convert 100w to t8?

[clanure]

Hello,

This is my first post and admittedly I'm a bit of a noob, but I've been reading on here for a couple of weeks now and have already tackled a unit heater install with help from you guys. This question however escapes my 'search' capabilities.

I've got a 3-car attached garage that has 3 100w standard incandescent fixtures all on a single switch. It's obviously not enough light for any practical work. I'd like to switch these out for some t8 fixtures, but I'm not sure how many t8 fixtures I can put on that circuit or even how many circuits I need to add to get enough light.

The walls/ceiling are all drywall, so the less I have to cut into the better, but I want to do it right.

Any help would be greatly appreciated!

 

[41ratrod]

we'll need more details like how big is your shop . The 100W bulbs will pull
more amps then the T8's . If you have a small garage I'd say 4 T8s would be
good.

 

[Showkey]

The other cost effective choice is a large CFL bulbs with or with out reflector depending on the ceiling.

Example 150 watt equivalent using 42 watts and 2800 lumen output. There are 300 watt equivalent at using about 65-75 watts.

Obviously there are always compromises........this can put 1000 LUX on the floor below the bulbs depending on conditions for less than $10 per fixture all in using less than half the power.

 

[CNGsaves]

^ ^ THIS is spot on.

OP you need to read the thread by Veno . . .
. . . . . . Lighting and CLF

He had a Type-o in the title as it should have been CFL . . . .

With oversize CFL's in normal porcelin socket fixtures, he has very nice lighting setup in his garage.
See at:
http://www.garagejournal.com/forum/showthread.php?t=38658&highlight=veno+clf

 

[cybrdyke]

2 lamp T8 fixtures normally use 59 watts, so you could install 2 of them @ 118 watts and not significantly increase your draw from the socket. You'd have 6500-ish lumens spread out over a wide area.
Hope this helps.
Good luck
CD

 

[Electric_Light]

Hello,

This is my first post and admittedly I'm a bit of a noob, but I've been reading on here for a couple of weeks now and have already tackled a unit heater install with help from you guys. This question however escapes my 'search' capabilities.

I've got a 3-car attached garage that has 3 100w standard incandescent fixtures all on a single switch. It's obviously not enough light for any practical work. I'd like to switch these out for some t8 fixtures, but I'm not sure how many t8 fixtures I can put on that circuit or even how many circuits I need to add to get enough light.

The walls/ceiling are all drywall, so the less I have to cut into the better, but I want to do it right.

Any help would be greatly appreciated!

What KIND of incandescent fixtures do you currently have?

 

[Elginz]

Not seeing it, one option my be to replace the bulb sockets with the octagon covers that hold a receptacle, plug in 2- 2 lamp T8 fixtures in each.

 

[Showkey]

What KIND of incandescent fixtures do you currently have?

How many kinds would there be in the standard run of the mill three car garage, on a single switch mounted in drywall, that hold the standard 100 w bulb. ?????

 

[DC73]

2 lamp T8 fixtures normally use 59 watts, so you could install 2 of them @ 118 watts and not significantly increase your draw from the socket. You'd have 6500-ish lumens spread out over a wide area.
Hope this helps.
Good luck
CD

@clanure - This is the information you need to start with. Based on cybrdyke's numbers you can install 5 2-lamp T8 fixtures with no increase in wattage compared to what you have now.

If you could figure out what other electrical loads are connected to this particular circuit, you could likely install many more of the 2-lamp T8 fixtures. For example, if this was a 20 Amp circuit (with #12 wire and a 20 Amp breaker), it would have a maximum circuit capacity of 2,400 watts. De-rating the circuit to a safe 80% of maximum would get you a capacity of over 1,900 watts. That's enough capacity to install 32 of the 2-lamp T8 fixtures assuming nothing else was connected to the circuit.

DC

 

[CNGsaves]

^ ^ ^ 64 T8 light bulbs would light up 3 car garage brighter than Vegas !!!

OP you might consider to leave the 3 porcelin fixtures with big CFL bulbs on the existing switch you have (see Veno thread above). This would be general lighting when not doing too much in garage.

Then, your T8's would be newly wired on own circuit/switch when you want "super bright" light in portion of shop you use the most. With about 6 fixtures (2 bulb T8's) your entire shop in conjunction with the 3 bright CFL's, I'd say you'd be daylight bright.

 

[Electric_Light]

How many kinds would there be in the standard run of the mill three car garage, on a single switch mounted in drywall, that hold the standard 100 w bulb. ?????

Not too many, but they're hugely different in how efficient they are in passing the light through. The one with a frosted glass dome only lets through about 50% of light.

 

[clanure]

Thank you all for your replies. I definitely have a bunch of things to consider, but everything seems like it's going in the right direction. I like the idea of large CFL's to replace the incandescent's and adding T8 fixtures to round it out, but don't like the idea of running new lines (walls are already sheetrocked). Anybody have an idea of what adding conduit to the project adds to the cost (25% or more)?


Those 3 lights are all that is on that circuit and it's got a 15 amp breaker in the box, so what can I do with that? I'd be happy with 10-15 2 bulb T8's.

Thanks again!

 

[FordTruckWench]

Anybody have an idea of what adding conduit to the project adds to the cost (25% or more)?

Conduit itself is really cheap.

What's "behind" your existing light fixtures? Do they have a square box behind them, flush with the sheetrock surface? How is the positioning of the lights in the garage?

If there are usable junction boxes, you could install T8 fixtures over the boxes. Additional T8's could be slaved to those using conduit.

Those 3 lights are all that is on that circuit and it's got a 15 amp breaker in the box, so what can I do with that? I'd be happy with 10-15 2 bulb T8's.

Using DC73's formula, you could run 24 dual bulb T8's.

 

[landyacht]

Don't assume that the 3 lights are the only thing on that circuit. Unless it was wired as a shop with expansion room added, I wouldn't be surprised if some outlets are on there too. It's easy to assume only lighting would be on a breaker and only plugs on another, but often its a mix. Could be some of your garage plugs, outside plug, lights or plugs in adjoining rooms (if it's an attached garage) or lights outside the garage. Just maybe get a plug tester and do a more detailed check.
If it's a mixed circuit, especially it it's with the garage plugs, I would give some extra consideration to running a new circuit, switch, and lights for your expanded lighting. Nothing worse than a power tool tripping a breaker, and the lights turn off too.

 

[DC73]

Thank you all for your replies. I definitely have a bunch of things to consider, but everything seems like it's going in the right direction. I like the idea of large CFL's to replace the incandescent's and adding T8 fixtures to round it out, but don't like the idea of running new lines (walls are already sheetrocked). Anybody have an idea of what adding conduit to the project adds to the cost (25% or more)?


Those 3 lights are all that is on that circuit and it's got a 15 amp breaker in the box, so what can I do with that? I'd be happy with 10-15 2 bulb T8's.

Thanks again!

Running new wire inside walls is not all that difficult depending on how much access you have from the attic. You can use what's called an "old construction" switch/outlet box. Cut out the sheet rock just enough for that box in the desired location for the switch or outlet. Drill a hole in the top plate from the attic. Drop a chain or cord through the hole. Fish it out of the hole you cut for the box. Tie your new cable to the chain and pull it up into the attic. Install the box in the wall. Make your connections. Done.

Spend some time with Google on this one and you'll find plenty of articles and videos to give you some ideas. And, make sure you are aware of where plumbing, air ducts, etc. might be located within a wall. You wouldn't want to cut into that.

Conduit on the outside of the wall is not a bad option if you don't mind the look.

With a 15 Amp breaker you're good for around 1,440 watts on the circuit. As FordTruckWench mentioned , that's a total of 24 2-lamp T8 fixtures. So you could easily add the 15 you want to the existing 3 lights you already have IF you are positive that circuit has nothing else on it.

DC