Garage Makeover - Electric 101

[jake26]

Hi gang,

I am currently working on my garage makeover and I spent the last 2 hours reading all the advice on the Lighting & Electrical board looking for some answers to some of my many questions. I think I developed a plan and now I am looking to see if I am on the right track. I have done basic wireing and I will have friends who can help but I would rather run my plan past you guys. Better to seem foolish to complete stangers I guess. Anyhoo, here it is.


* Run a 50 amp service to attached garage using 12/3 wire.
* Use 8/2 wire to run to outlets and lights
* Use GFCI outlets to start each circuit then normal 20 amp outlets after
* Use 12/2 wire to run outside to 175w flag lamp
* Use metal gang boxes
* Use 12 T8 lamps to light a 24' x 25' garage

The garage is not being used as a shop but I want to have some options. I will be running a 220 outlet for an electrical heater. Does this sound right or idiodic?

Now some specific questions:


* Some suggest using GFCI breakers and regular outlets instead of GFCI outlets. Is that better?
* Am I safe running all 20 amp outlets? Can they be to big for some electrics?
* When wiring for the lamps, do you install gangboxes and hardwire or better to install outlets and plut them in (I have not chosen my lights yet)
* I have had problems with my GFCI outlet in the garage. My little Sears compressor and Fridge runs like sh$t on it or it trips all the time. Should I have some non-GFCI outelts for that reason?

I know this is alot but any help is appreciated. Many thanks

 

[csp]

12ga wire is only rated to 20 amps.

You probably should have typed 8ga for your 50 amp service and 12ga wire to outlets and lights.

The smaller the number the larger the wire and capacity.

 

[Boiler]

8/3 is bigtime overkill for receptacles. From what I understand 20 amps per receptacle chain / duplex box is the max, and 15 amps per receptacle, all of which can be carried by 12/3.

Also my chart next to my computer shows 40 breaker amps for 8 gauge, 55 breaker amps for 6 gauge. Not sure if thats right, and you can find different info just about anywhere you look. That's what I use for machinery feeds though.

 

[oleguy]

50 amp to garage service needs to be 6-3 and ground.#12-2 for outlets.12-2 or 14-2 for lites.keep them seperate.20 amp outlets ok.gfi outlets or breakers what ever you want.outlets fine for lites,put frig and comp on thier own ckt.

 

[rodnok1]

I used all plastic boxes, cheaper and easier to work with. The new one's are alot tougher then the old one's. Buy the biggest boxes they have to avoid overfill(plus with 12 g wire it's just easier)

 

[Charles (in GA)]

20 amp receptacles are a waste of money. There is practically nothing that plugs into them, and the truth is, a high quality 20 amp receptacle and its matching quality 15 amp receptacle (such as Leviton Pro Grade backwired) have the exact same innards in them with different face plates.

Using a 20 amp GFCI is also a waste as 15 amp ones have a 20 amp feed through.

Here is what a 20 amp GFCI looks like. 20 amp receptacles accept plugs with a horizontal neutral blade (very uncommon on most "appliances")

It is quite legal to use a 20 amp breaker, and 12-2 w/ground wire and 15 amp receptacles, so long as there is more than one receptacle in the circuit.

Charles

 

[expatriated]

Good questions.

When running wire from the breaker box to a gfci outlet and then to normal down the line outlets, I understood 14 was ok. Do I need to use 12ga?

 

[oleguy]

Good questions.

When running wire from the breaker box to a gfci outlet and then to normal down the line outlets, I understood 14 was ok. Do I need to use 12ga?

if it is a 20 amp ckt no.#14 is 15 amp.

 

[expatriated]

Thank you. I should have known that.

 

[Jack90210]

20 amp receptacles are a waste of money. There is practically nothing that plugs into them, and the truth is, a high quality 20 amp receptacle and its matching quality 15 amp receptacle (such as Leviton Pro Grade backwired) have the exact same innards in them with different face plates.

I like having the "headroom" that you get when you start a big motor that draws close to 15A at startup -- especially if you have anything else plugged in on that circuit.

I also like having the ability to insert a 20A plug if I have the need.

And ditto on using quality receps. I used spec grade in my garage.

 

[Charles (in GA)]

I also like having the ability to insert a 20A plug if I have the need.

I put one single 20 amp receptacle in my shop "just in case". I'm yet to encounter anything with a 20 amp 120V plug on it, though I suppose some 120V mig welders might have them. Given a fairly substantial difference in price between a 15 amp receptacle and a comparable 20 amp receptacle, it doesn't make much sense to install a whole bunch of 20 amp receptacles you probably will never make use of.

Examples of price difference (though somewhat extreme possibly)

At Grainger, Hubbell standard duplex receptacle, industrial grade, 15 amp is $10.45 while the 20 amp of the same industrial grade is $15.51.

Hubbell duplex receptacle, commercial grade, 15 amp is $7.51 and 20 amp is $11.13.

You see similar differences between 15 and 20 amp in Leviton ProGrade and Eagle's commercial lines at Home Depot and Lowes.

Bust any of them open and you will find the same innards in a 15 and the 20 amp of the same brand, I've done it. The 15 amp has the contacts for the horizontal neutral blade of the 20 amp 5-20P plug, its just that the 15 amp face plate blocks it off.

Charles

 

[jake26]

Thanks to everyone who responded.

I had none of my information correct but now I think I understand <somewhat>.

A revised list:

* Run a 50 amp service to attached garage using 6/3 wire.
* Use 12/2 wire to run to outlets
* Use 14/2 for lights (I may stick with the 12/2 to avoid confusion)
* Use GFCI outlets to start each circuit then normal 15 amp outlets after
* Have fridge on separate breaker
* Use 12/2 wire (w/ heavy insulation for burring) to run outside to 175w flag lamp
* Plastic gang boxes are fine (the bigger the better)

Does that sound better? I wish I could buy everyone a beer because am sure to have tons more questions.

Thanks again!!

 

[Brandon_K]

Use 12/2 for any/all of your 15/20A circuits. The cost difference is slim and it saves you from needing to buy a coil of 14g, that you won't use all of, just to run lights.

I would recommend GFCI breakers over receptacles. At that point all of your trip indicators are in one location (the panel) and you don't need to search to figure out what GFI outlet controls the other "slave" outlets.

I would also recommend installing double gang boxes with 2 duplex's per box and wiring it as a MWBC (this cannot be done with GFI protected outlets, however). Never again will you need to search for an outlet tap (splitter, 1to3, whatever terminology you may want to use). The cost difference on the box is small, the cost of an additional duplex, even when buying an additional 10 or 15 receptacles is fairly small and you only need to pull 1 additional wire (2 hots, 1 neutral, 1 ground) or simply use 12-3.

If you know where you normally keep motor-load devices, consider running individual circuits for them. Large drill presses, compressors, 120v welders, bench grinders, etc. It's nice to know that when you're trying to ream out a piece of 1/2" plate in the drill press and you're buddy is over buzzing together your frame rail, you're not going to pop a breaker.

Plastic boxes are nice because they don't have to be pigtailed and grounded like a metal box.
My 2c.

 

[csp]

20 amp receptacles are a waste of money. There is practically nothing that plugs into them, and the truth is, a high quality 20 amp receptacle and its matching quality 15 amp receptacle (such as Leviton Pro Grade backwired) have the exact same innards in them with different face plates.

Not all 20 amp rated outlets have the horizontal leg. My entire house, other than the furnace circuit is 20 amp and none of the outles have the horizontal leg other than a few in my garage. My 110v welder requires that type of outlet.

Anything with two vertical legs will also plug into these, so saying practically nothing plugs into them is a misnomer. Very few plugs require them, but everything 110v will plug into them.

 

[Charles (in GA)]

Not all 20 amp rated outlets have the horizontal leg. My entire house, other than the furnace circuit is 20 amp and none of the outles have the horizontal leg other than a few in my garage. My 110v welder requires that type of outlet.

Anything with two vertical legs will also plug into these, so saying practically nothing plugs into them is a misnomer. Very few plugs require them, but everything 110v will plug into them.

Sorry I did not make myself clear. You are correct, very few plugs require them, but all plugs will fit them. That is my argument, so few appliances or tools have the horizontal plug (NEMA 5-20P), that its a waste of a substantial amount of money to install them except where you really need them. Use good quality 15 amp receptacles instead.

You are incorrect in stating that "not all 20 amp rated outlets have the horizontal leg", this is part of the UL certification for the device, and is used as a method to prevent someone from overloading a circuit by plugging in a piece of equipment that requires more current than the circuit is capable of.

(Note: I assume when you refer to "outlet" you are using the layman's description of a receptacle. I'm aware that an "outlet" in the NEC is "A point on the wiring system at which current is taken to supply utilization equipment", meaning any place where electricity can be tapped for use, but very few readers of this board probably use this broad of a definition.)

It allows you to plug either 15 amp or 20 amp plugs into a 20 amp receptacle, but makes it impossible to plug anything but a 15 amp plug into a 15 amp receptacle.

NEC 210.21(B)(3) allows 15 amp rated receptacles to be installed in circuits that are 20 amp "rated" (meaning 12 gauge wire and 20 amp breaker) provided that there is more than one receptacle in the circuit. That is what you are talking about in your house. I'm not discussing circuits, I talking about the physical receptacle itself. I assume that anyone building or modifying a shop or garage is going to use 12 gauge wire and 20 amp breakers on the circuits for the general use receptacles.

The UL listing of the plugs and receptacles are dependent on their having either NEMA 5-15 or 5-20 configuration. They are not going to certify a 5-15 configuration receptacle to 20 amps. My argument is, however, good ones frequently have the guts of a 5-20 configuration hidden behind the 5-15 face plate and this tells me they are "overbuilt" and should be able to carry anything demanded of them.

For me, its a matter of money vs needs. I cannot see spending or recommending that someone else spend several dollars a receptacle more to get something that will not benefit them in most cases. If they have something like a MIG welder that requires a NEMA 5-20 configuration receptacle, then install one where they need it, but don't install a whole shop full where they are not needed.

Charles

 

[jake26]

Quick question:

Any idea why my air compressor and fridge will run poorly on the GFCI outlets? The fridge will constantly trip the outlet and the compressor motor will putter and stop. Could it be a bad outlet?

Thanks!!

 

[rodm1]

20 amp receptacles are a waste of money. There is practically nothing that plugs into them, and the truth is, a high quality 20 amp receptacle and its matching quality 15 amp receptacle (such as Leviton Pro Grade backwired) have the exact same innards in them with different face plates.

Using a 20 amp GFCI is also a waste as 15 amp ones have a 20 amp feed through.

Here is what a 20 amp GFCI looks like. 20 amp receptacles accept plugs with a horizontal neutral blade (very uncommon on most "appliances")

It is quite legal to use a 20 amp breaker, and 12-2 w/ground wire and 15 amp receptacles, so long as there is more than one receptacle in the circuit.

Charles

Will the 15amp "backwired" take 12ga wire? All the ones at the home centers only take 14ga.

 

[Norcal]

Will the 15amp "backwired" take 12ga wire? All the ones at the home centers only take 14ga.

When someone uses cheap receptacles they cannot be backwired w/ 12 AWG wire one has to wrap the conductor around the screws, buy a quailty device w/ pressure plates & one can backwire. "Backwire" is also called "Push & Pray", push them in and pray they stay in.(The above statement does not apply to pressure plate type devices).

 

[Charles (in GA)]

As already noted, the push in and make connection via a spring finger, is, by code, only allowed to use 14 gauge wire. The commercial and industrial backwired receptacles I am referring to are ones where you loosen the screw on the side, push in the wire, and tighten the screw. It pulls a serrated or V notched plate inside up tight on the wire and pinches it in place, making a very good connection. These will take 12 gauge with no issue. The GFI receptacles I've used also are this type of screw clamp backwire and also take 12 gauge. Easily found in Home Depot or Lowes.

Charles

 

[Norcal]

It's not a NEC issue that backwired devices only accept 14 AWG, it was a UL listing change.

 

[rodm1]

As already noted, the push in and make connection via a spring finger, is, by code, only allowed to use 14 gauge wire. The commercial and industrial backwired receptacles I am referring to are ones where you loosen the screw on the side, push in the wire, and tighten the screw. It pulls a serrated or V notched plate inside up tight on the wire and pinches it in place, making a very good connection. These will take 12 gauge with no issue. The GFI receptacles I've used also are this type of screw clamp backwire and also take 12 gauge. Easily found in Home Depot or Lowes.

Charles

I take it as a Yes to 15amp?

 

[Charles (in GA)]

It's not a NEC issue that backwired devices only accept 14 AWG, it was a UL listing change.

Thanks for the correction, knew it wasn't allowed, didn't know exactly who didn't allow it. They should not allow any push in tension connections.

Charles