Another garage question - electrical capacity?

[J-hop]

So I’m an absolute moron when it comes to understanding electrical systems so looking for some advice/guidance on setting up my garage.

What I really want to figure out is if I can run higher wattage LED light bars (2) that put out about 11,000 lumens each, and draw 148watts each for a total of ~300watts draw.

I took a look and unfortunately my garage is on a single 15amp circuit. I am trying to figure out if I can run these light bars without pushing the circuit too far.

All the wiring - out to the current light sockets and I assume wall sockets in the garage is 14/2 wiring which seems from my research to be sized appropriate for a 15amp circuit.

My total max draw with these LED bars installed would be:

3 exterior bulbs, I think 100watts each = 2.5amps
Wired impact gun = 8.5 amps
Potential LED bars = 148w*2/120 = ~2.5 amps

For a total of 13.5 amps.



This seems a little on the high size but I should be OK right? Is there a rule for the max one should draw on a regular basis? When I use the impact gun its not like I’m sitting there for a half hour, maybe 10 minutes at a time kind of thing.

I am thinking I can gain some room by switching the 3 outdoor lights to 100w equivalent LEDs which should draw about 20w each and reduce the total max draw to 11.5 amps, that makes me a bit more comfortable.

Obviously I probably won’t be running the outdoor lights when I’m working inside but I’m trying to account for all possible scenarios.

Is there anything I’m overlooking here? Am I good to go with replacing my current light sockets with two 148w LED light bars?



Finally, I can’t find at all what the draw of the garage door opener is. Anyone know how to figure this out? It is a 1/2hp unit but the website gives nothing for current draw specs. I believe the 1/2hp rating would be the output power? I can convert that to watts and I get 373 watts which converts to a 3.1 amp draw. So I can say 3.1amps minimum draw but probably draws more than that due to losses?

Sorry for the poorly formed questions!

[Darell_n]

My spice drawer has more power available to it than your garage. I would definitely work on fixing that before anything else. I’m guessing you don’t have a breaker panel in your garage.

[J-hop]

My spice drawer has more power available to it than your garage. I would definitely work on fixing that before anything else. I’m guessing you don’t have a breaker panel in your garage.

Haha no doubt.

No unfortunately no sub panel.

Beautiful garage structurally but piss poor electrical wise.

Is the wiring sheathed/fishable on newer builds or will it need to be ripped up?

I can see a sheath on the wiring where it comes out of the garage but no idea if that is run the whole way

[firebane]

I'm not sure what breaker amperage my garage uses but I'll have 2 LED lights, 1 regular incandescent bulb, 1 fan and sometimes a grinder, bench grinder or a welder and never have an issue.

[J-hop]

My other idea (as 22,000 lumens may be a lot of overkill), is to run 4 of these: https://www.homedepot.ca/en/home/p.4-ft-linkable-led-shop-light.1000823032.html

Would these (when linked) be in parallel or series? If parallel I add the power and divide by 120 to get the current draw right so 4x35/120 =1.2 amps?

Also I would prefer to replace my light sockets with 3 prong plugs than try to strip the light wires and wire them up, what exactly do I do for ground?

[firebane]

My other idea (as 22,000 lumens may be a lot of overkill), is to run 4 of these: https://www.homedepot.ca/en/home/p.4-ft-linkable-led-shop-light.1000823032.html

Would these (when linked) be in parallel or series? If parallel I add the power and divide by 120 to get the current draw right so 4x35/120 =1.2 amps?

Also I would prefer to replace my light sockets with 3 prong plugs than try to strip the light wires and wire them up, what exactly do I do for ground?

How large is your shop? I have 2 and will be putting in a 3rd 48" led light and my shop isn't very big and those 2 lights put out a ton of light. And its nice in the dead cold they will power on unlike your tube lights.

If you want to convert your single bulb socket to something you could use this https://www.amazon.com/KINGSO-Splitter-Converter-Adjustable-Resistant/dp/B01EFM8SIO and then use LED bulbs.

[J-hop]

How large is your shop? I have 2 and will be putting in a 3rd 48" led light and my shop isn't very big and those 2 lights put out a ton of light. And its nice in the dead cold they will power on unlike your tube lights.

If you want to convert your single bulb socket to something you could use this https://www.amazon.com/KINGSO-Splitter-Converter-Adjustable-Resistant/dp/B01EFM8SIO and then use LED bulbs.

It’s small, just a 20x22 (I think) garage. What light bars are you running?

I currently have similar to what you’ve posted (but just a two bulb) but would like light bars/panel for a bit more spacially consistent lighting. It’s pretty good but where the light socket is when I have the hood up the engine is in shadow.

[firebane]

It’s small, just a 20x22 (I think) garage. What light bars are you running?

I currently have similar to what you’ve posted (but just a two bulb) but would like light bars/panel for a bit more spacially consistent lighting. It’s pretty good but where the light socket is when I have the hood up the engine is in shadow.

My shop is about the same size and I have 2 of the 48" lights from Costco and will be putting in a 3rd from Lowes and there is no lack of light. If I had 4 in there it would be almost blinding bright.

[90_Shelby]

This is a good guide for DIY electrical. http://www.calgary.ca/PDA/pd/Documents/brochures/Homeowner-electrical-wiring-guide.pdf

[J-hop]

This is a good guide for DIY electrical. http://www.calgary.ca/PDA/pd/Documents/brochures/Homeowner-electrical-wiring-guide.pdf

Rats so it looks like if I wanted to run more power out there i’d Have to dig up the line. The protective pvc won’t be up to code.

I’ve thought about it a bit more and I’m going to do 4 of the 35 watt led light bars. Not clear from that DIY how I’m going change the light sockets into a 3 prong outlet but I’ll do a bit more reading!

Edit: actually firebane how many prongs on the Costco light, 2 or 3?

[Crazyjoker77]

Your kind of all over the place but really you shouldn't have much problem with your original 2x148W fixtures. Just don't go adding much more stuff especially heat producing devices.

You were on the right track figuring out your loads but you have to consider that the ratings on the impact gun and garage door opener(pretty much anything with a motor) are the max current they can draw but they will actually draw a less(what they draw depends on the mechanical load upon the motor) and they are not continuous loads and are pretty unlikely that they will ALL be ran at the exact same time. This is what is refereed to as demand factor.

The breakers (and fuses) used in residential are thermal based and as such don't just majically trip the second they see 15A. They work by building up heat and can take short overload situations.


As for converting the light sockets into receptacles its fairly easy. It will more than likely be a octagon junction box that the exisitng fixture is wired into. Once the fixtures removed you can go with 2 different options.

Plug box cover if you just want a standard receptacle. (which I personally dont recommend. as its been my experience that with a downward facing straight blade the plug will tend to keep coming loose from the vibrations from the garage door opener) So i would look at a locking receptacle
https://images.homedepot-static.com/productImages/48070236-db14-4b62-9c9a-0ab5ed1dca63/svn/steel-city-covers-5402lr-25r-64_1000.jpg

Or you can cut the plug end off the fixture and hardwire them in like the existing fixtures.
https://i.ebayimg.com/images/g/qEkAAOSwcwhVP8nr/s-l300.jpg
https://media.rs-online.com/t_large/F7023283-01.jpg

[Cword]

You still haven't mentioned what type of work you're going to try to do.
That 15 amp service is going to be pretty disappointing if you fire up a saw, an air compressor, a welder.

Part of your consideration as to whether to run a bigger service out there is how long (years) you plan to work in that shop, and put up with blowing breakers. As well as what types of work you see yourself getting involved in in the future.

I'd be seriously pissed if my compressor fired up while I was welding and the garage went dark.

[BerserkerCatSplat]

Rats so it looks like if I wanted to run more power out there i’d Have to dig up the line. The protective pvc won’t be up to code.


What's wrong with your PVC? Too small?

[firebane]

You still haven't mentioned what type of work you're going to try to do.
That 15 amp service is going to be pretty disappointing if you fire up a saw, an air compressor, a welder.

Part of your consideration as to whether to run a bigger service out there is how long (years) you plan to work in that shop, and put up with blowing breakers. As well as what types of work you see yourself getting involved in in the future.

I'd be seriously pissed if my compressor fired up while I was welding and the garage went dark.

When you are limited you realize that unfortunately you need to take turns.

[J-hop]

Your kind of all over the place but really you shouldn't have much problem with your original 2x148W fixtures. Just don't go adding much more stuff especially heat producing devices.

You were on the right track figuring out your loads but you have to consider that the ratings on the impact gun and garage door opener(pretty much anything with a motor) are the max current they can draw but they will actually draw a less(what they draw depends on the mechanical load upon the motor) and they are not continuous loads and are pretty unlikely that they will ALL be ran at the exact same time. This is what is refereed to as demand factor.

The breakers (and fuses) used in residential are thermal based and as such don't just majically trip the second they see 15A. They work by building up heat and can take short overload situations.


As for converting the light sockets into receptacles its fairly easy. It will more than likely be a octagon junction box that the exisitng fixture is wired into. Once the fixtures removed you can go with 2 different options.

Plug box cover if you just want a standard receptacle. (which I personally dont recommend. as its been my experience that with a downward facing straight blade the plug will tend to keep coming loose from the vibrations from the garage door opener) So i would look at a locking receptacle
https://images.homedepot-static.com/productImages/48070236-db14-4b62-9c9a-0ab5ed1dca63/svn/steel-city-covers-5402lr-25r-64_1000.jpg

Or you can cut the plug end off the fixture and hardwire them in like the existing fixtures.
https://i.ebayimg.com/images/g/qEkAAOSwcwhVP8nr/s-l300.jpg
https://media.rs-online.com/t_large/F7023283-01.jpg

Thanks for the great summary, yea I did more reading and it seems pretty straight forward. To do the plugs. My concern was the ground, but everyone I saw the receptacle had a third wire, so I’m guessing mine will too.

The reason I don’t want to hardwire the fixture is if I don’t like it or want to change it down the road I can easily return or sell the fixtures.

You’re right about the load ratings being max and not everything at once. Most likely the only things that will be run at once are indoor lighting, outdoor lighting and an impact gun.


What's wrong with your PVC? Too small?
15amp is to be run with 3/4 pvc pipe according to the CoC electrical guide. I’m guessing they wouldn’t have gone above and beyond the code. If I were to re-wire it I’d want at least 30 amps out there, you need a 1” pvc pipe to meet code apparently.

I’m just incredibly ignorant and in general pretty dumb so I want to be sure I don’t go into anything electrical blind

[J-hop]

You still haven't mentioned what type of work you're going to try to do.
That 15 amp service is going to be pretty disappointing if you fire up a saw, an air compressor, a welder.

Part of your consideration as to whether to run a bigger service out there is how long (years) you plan to work in that shop, and put up with blowing breakers. As well as what types of work you see yourself getting involved in in the future.

I'd be seriously pissed if my compressor fired up while I was welding and the garage went dark.

Just really basic automotive work: oil changes, general repair, suspension work, have a project car I have to swap an engine and turbo kit into. Nothing serious, I don’t do fabrication and have a friend that does any welding for me as I have very poor welding skills. With 120 and 15 amps to work with you’re right I can’t do anything serious.

[FraserB]

Are your garage walls finished already? If not, it might just be worth it wait until summer and rip everything out and re-wire it with a bigger service

[J-hop]

Are your garage walls finished already? If not, it might just be worth it wait until summer and rip everything out and re-wire it with a bigger service

Yea they are essentially finished. Entire garage is insulated with pressboard over it. I probably won’t drywall it. Dad’s is dry walled and it’s just annoying, constantly taking chunks out everytime something falls over and annoying when mounting stuff. Neighbor painted the pressboard and it looks pretty good.

Not super concerned with the service out there right now. So I’ll leave it be for the time being. It’s too small a garage to have a compressor and I don’t weld so I don’t really have any high demand items right now

[BerserkerCatSplat]

15amp is to be run with 3/4 pvc pipe according to the CoC electrical guide. I’m guessing they wouldn’t have gone above and beyond the code. If I were to re-wire it I’d want at least 30 amps out there, you need a 1” pvc pipe to meet code apparently.

I’m just incredibly ignorant and in general pretty dumb so I want to be sure I don’t go into anything electrical blind


Well, the CoC guideline is basically a check table that assumes you're running NMWU and gives conduit size based on fill volume % as per CEC. You can run way higher amperage in smaller conduit by using wet-rated stranded conductors like THWN/TWN (http://www.southwire.com/products/oem-thhn-thwn-twn75-t90.htm) or RW90 (http://www.southwire.com/products/SIMpull-CU-RW90.htm) instead of the bulky (and expensive) NMWU. I upgraded to 60A/240V service to my detached garage using the existing 3/4" PVC conduit and 3x TWN75 6GA conductors with a 8GA TWN75 ground. I verified with CoC and my inspector in advance that it met code and would be approved as it met conductor/amperage requirements and conduit fill volume percentages. I would have needed 1 1/2" conduit for NMWU and it would have sucked to pull through. Plus, the TWN75 was like a third the price of NMWU to buy locally. RW90 was even cheaper, but I needed the thinner TWN insulation to hit the conduit fill%.

The only complication with stranded runs is that they have to be run entirely in conduit. No big deal for underground as you're already in conduit, but indoors can be a pain. I ran it in conduit all the way to my panel entrances (it was a bit cheaper that way), but I could have transitioned to NMD90 via junction box where it entered the house and garage.

Long story short, if you do find yourself wanting to upgrade service, all hope is not yet lost - you have options for your existing conduit but you might need to get creative.

[J-hop]

^ thanks, that is really helpful if I decide to upgrade.

Going tonight to buy the light panels and sockets/plates. Probably won’t get around to installing until later this week but we’ll see.

Also thinking about putting the lighting on a motion sensor switch. The garage inside is so dark with just the door opener light which is pretty annoying when you’re trying to get groceries and/or the dog out of the car at night.

[BerserkerCatSplat]

^ thanks, that is really helpful if I decide to upgrade.


Happy to help! I actually misremembered - my conduit is also 3/4", not 1" like I thought. So if I can run 60A/240V through mine, so can you. If you wanted to save some $, you could do 8GA RW90 to get 40A/240V service for really cheap. Add a cheap subpanel and you'd be good to go.

Southwire has a handy conduit fill calculator (http://www.southwire.com/support/conduit-fill-calculator.htm) you can use, your PVC is likely Sched40 and wire thicknesses are available for anything Southwire makes. Other manufacturers may have slightly different specs but it'll be within a few %.

I found that buying locally, TWN 6GA was actually noticeably cheaper than 8GA because wholesalers will cut 6GA for you to length, but will only sell 8GA in 300m spools. I ordered my TWN 6GA conductors from Electrical Wholesalers but had to go through Lowes for my TWN 8GA ground wire, which per-foot was more expensive than the 6GA. I think 8GA RW90 was the cheapest but you'll have to check on that.

[J-hop]

Damn that is tempting now. I have two neighbors that are electricians I’m sure would be happy to help me for a case of beer...

[J-hop]

Crazyjoker77 (or others). When I picked up the lighting tonight I was looking at motion/occupancy light switches.

When I add up the lights on the circuit I get 4x35w=140w/120v =1.2amps. They only had the 2amp switch however that 2 amp switch said it was only rated for up to 150watt LED, what gives?

I was planning on going with the 5amp switch but I thought that was just weird.

Here is the switch in question

https://www.homedepot.ca/en/home/p.lutron-maestro-2-amp-single-pole-motion-sensing-switch-in-white.1000720113.html

[Crazyjoker77]

It all has to do with power factor which is something pretty deep to get into. Incandescent bulbs are a pure load which means apparent power (va) and true power(w) are equal. When your dealing with anything that has transformers, capacitors, or synchronous motors, you will have a leading or lagging power factor and the true power will not equal the apparent power. You should be using the VA of the bulbs to figure out what it will actually be pulling. Those bulbs will actually pull more than the 1.2A you calculated but manufactures rate the bulbs in W because thats what people are use to seeing with traditional incandescent. Honestly most LED now a days have a very good power factor and are withing 90-95% of the true power but some of the cheaper ones can be pretty low so the switch manufactures put that in their to cover themselves. It usually is not an issue to be concerned with.

What mayl be a issue that you are going to run into is that I'm assuming it is just a toggle switch controlling the existing lights, which means you are more than likely not going to have a neutral to hook up the new switch to. Traditional switches don't need a neutral but some dimmers and motion sensor(pir) requires one. To make it to code you will have to run a neutral from the light fixture down to the light switch box which sucks if your garage is already finished. Some hacks will just use the ground wire in the box which WILL work but is very against code as the ground is not meant to carry current except in fault situations.

[J-hop]

Man thanks a ton this is really great Crazyjoker77. Did some reading and understand (at least somewhat) what you’re saying. Can’t seem to find what the apparent power for these fixtures is. I’ll plan for the minimum standard. Looks like in the US the minimum power factor is 0.7 for residential LEDs. Looks like that switch manufacturer is giving a bit of leeway on that as well with 0.62. This makes sense with their 5Amp switch that is using a factor of 0.6.

I’ll go with the 5amp switch as I originally planned just to be more than safe. I don’t want to be butting up against the max rating.

Thanks again the guys at homedepot didn’t have a clue when I was asking why the math didn’t add up. They acted like I was being an idiot haha which may be true but not on a relative scale in this case.

Your comment about the neutral totally makes sense now. My father in law installed a motion sensor switch in his kitchen. I always wondered why the fluorescent bulbs glowed ever so slightly when it was on the motion setting and no one was in the room. I’m guessing now that it’s one of those motion sensors that the manufacturer tried to get around the lack of a neutral by allowing a small current through to run the sensor, but it’s obviously just enough to power the light a bit as well.


So I could be wrong here but all of my wiring in the garage to the lights is 14-2. I think this means I should have a hot, ground and a neutral so I should be ok? If not since my garage isn’t dry walled and the rafters are not closed it would be super easy to run a new wire. Guessing I should technically permit and have that inspected if I do end up having to rerun wires? Not a big deal and a good learning experience

[Crazyjoker77]

Switches use the wires as hot, switch leg, and ground no need for a neutral on a regular toggle switch so contractors cut cost by not running it. You need 14/3 to have a switch function AND have a neutral. You will find the white wire is actually the hot(it may have a couple wraps of black tap around the ends) and the black is the switched hot that ties into all the fixtures.

Technically you should pull a permit but its such a small job there a good chance he would just sigh and face palm when he showed up. If everything is accessible now just replace the 14/2 with 14/3 from the fixture box its coming out of. Swap the current white wire for one of the colored ones and tie the white into the rest of the neutrals.

The neutral thing isnt really the reason why the fluorescent bulbs glowed it has more to do with the differences of switching methods. A traditional switch uses an actuall physcal opening to stop all the current where as in most electronic based switches use a solid state electronic switch of some sort (SCR,IGBT,Triac,) .All SS switches will have a tiny amount of leakage current going through them at all times. This little bit of leakage current is what causes the faint glow.

The switches without a neutral will rob you of a little bit of brightness on incandescent bulbs OR pull a little but more current(negligible) when used on lighting with a driver/ballast.

Honestly your trying to calculate it way to much. At this level your going to have more of a variation just because the voltage isn't going to be constant 120v throughout the day for various reasons. A little bit of power factor or power phantom losses isn't go to make any meaningful difference on a single 15A circuit.

[J-hop]

Thanks, Yea I know I’m going overboard. But the “I just did it and it works fine” mentality doesn’t sit right with me. I want to why and how haha

I guess I’ll have to look at a wiring diagram to understand why I need 14-3. 14-2 is a 3 conductor wire. The diagram I looked at showed it as hot, ground and neutral so guess I’m not able to visualize why I’d need a 4th wire between the switch and fixture?

[Crazyjoker77]

You related to mar by chance?

Here it is in the most basic form. Cable 2 needs 3 wires (stop counting the ground as a wire) 14/2 technically has 3 wires but its called 14/2 because it only has 2 current carrying wires.

white wire is depicted as yellow. Ground wires are not shows cause the have no impact and are always going to be included with the lumex.

https://i.imgur.com/jVTyWK7.png

Also neutral is the incorrect term. The white wire is actually called the identified grounded conductor.

[J-hop]

thanks, yea sorry I’m an absolute moron so it takes a while for stuff to sink in.

I just look at this like building cars. You can know less than nothing and get away with some shitty brainless off the shelf tune if you’re running a very mild setup. But as soon as you step up and try to build a serious engine the guys with that mentality start to pay heavily for their ignorance.