General electrical questions for my garage.

[jake26]

Hi Gang!

After a long absense caused by a sickness, an injury and my Dad passing away, I am trying to get back into my garage makeover. I am now ready to start laying out the electrical but I have some general questions.

1) How high should the recepticles be installed? These outlets will be along the walls and have no purpose except for convience. My original plan had them at 2 feet off the floor but a friend said he made all his outlets and switches 42" off the floor. What works better since I have no experiance in either?

2) I plan on hard wiring my lighting fixtures but I do not know how to set up the connection points in my future ceiling. Do you just have wires in place above the drywall to later penetrate and connect to the lights or do you install a light or juntion box to store the electrical in?

Thanks for any help.

 

[fefarms]

If you set the bottom of the receptacle box at 48 inches aff (above finished floor), you can lean 4 foot sheet goods against the wall and still get at the receptacle. This also gets the receptacle above benchtop height, and also above the 18 inch "hazard zone" associated with pooled gasoline vapors. For extra credit you can fine tune the box height to optimize the ease of finishing the walls (adjust it so you only have to cut one sheet of drywall/plywood/OSB). This is a little too high for a switch box, the "natural" or "expected" height of those is around the 42 inch number.

As an aside, some building designers urge the use of a 34 inch switch height, to make the building semi-ADA-compliant. They say you eventually get used to the low placement of the light switches, and that this will make life easier if you ever end up in a wheel chair.

How to handle ceiling wiring depends on your choices of light fixtures and how good the access is to the attic space above the ceiling. (With good attic access you can run the wires after finishing the ceiling.)

Assuming difficult attic access, for a dome fixture like an ordinary household lamp you need a box mounted in the ceiling. For an enclosed fixture like a fluorescent striplight you can either use a box like above, or coil a stub of romex and tie it to the stud. As you finish the ceiling you cut a hole for the wire and pull it through the hole. As you mount the fixtures you can pull the stub into the fixture enclosure.

If you don't mind an industrial look, you can use continuous rows of tandem channel striplights. Pull a stub into the end fixture, then wire the rest of the fixtures using the fixtures themselves as a form of "wireway". All the wiring and connections end up inside the fixtures themselves.

 

[Falcon67]

Most people put them 48"+ off the floor because it lets you put an uncut piece of 4 x ?? wall board under the outlets. If the walls are finished, pick a comfortable height and just mount them consistently.

My light plan for the new shop is to drill the ends of some 4' fixtures to accept 1/2 or 3/4 conduit ends and string them together in a line of three. Haven't decided whether to place 4" boxes at the wall and run conduit out to the the first fixture in the row or place a 4" box in the ceiling over the first fixture location and run in from there.

 

[mrb]

fyi with flourescent lights, you cant mount them over a box unless there is a hole in the fixture the size of the box.

 

[Berserker]

I too agree with 48". Garages have lotss of junk put up against the walls. Plus thew gas vapor down low.

Also gets you above any bench or table you may someday put in.

 

[jake26]

Thank you all for the suggestions. 48" mounting height for the win!

As for the wires through the ceiling, I had planed on using a junction box where each florescent fixture was to go because I had planed on stringing them all together and I assumed that was the best approach.

Currently, I have access but I also made a storage area in the attic so when the garage is completed, the wires will be between the drywall and the subfloor in the attic.

 

[thrifty bill]

Thank you all for the suggestions. 48" mounting height for the win!

As for the wires through the ceiling, I had planed on using a junction box where each florescent fixture was to go because I had planed on stringing them all together and I assumed that was the best approach.

Currently, I have access but I also made a storage area in the attic so when the garage is completed, the wires will be between the drywall and the subfloor in the attic.

Depends on the style of light. I often use those two bulb florescent shop lights, that hang on two chains from the ceiling, and usually come prewired with a plug. So I just put outlets in the ceiling, connected to the light switch. Depending on how many lights you install and the spacing, I typically plug in two lights to each outlet. Looks kind of basic, so if you are building a showplace, you might want to use better fixtures. Me, I have used those shop lights so many times, I am used to the look, and like the price (typically under $10 at your local big box store).

Depending on the size of the garage/shop, I will typically zone the lights, from front to back, three zones or so. Really depends on the size of your shop, and its layout. I am planning to build a larger shop, I'll probably have at least four lighting sections (separate switches). In this case, I will probably zone them side by side, as I will have three garage bays, plus a workshop area on each end.

 

[Berserker]

Its nice to have atleast one light on another circuit breaker, in case you need to replace a light, your not in the dark. Which is why they do plugs.

 

[Steevo]

fyi with flourescent lights, you cant mount them over a box unless there is a hole in the fixture the size of the box.

Is this an electrical code issue?

So, if you are going to run 8' fluorescent fixtures, you just poke the romex down through the sheet rock and through one of the knockouts in the back of the housing?

What if you have a ceiling box already there, and want to replace the flush fixture with a fluorescent unit? Can't you just bring the wires down into the fluorescent housing through the knockout hole (same as with no box) and use the electrical box in the ceiling as nothing more than a pas-through for the Romex?

Or do you have to cut out the hole in the fluorescent fixture from knockout size up to a 3-1/2" box size, just to have the same single Romex wire come through it?

 

[mrb]

Is this an electrical code issue?

So, if you are going to run 8' fluorescent fixtures, you just poke the romex down through the sheet rock and through one of the knockouts in the back of the housing?

What if you have a ceiling box already there, and want to replace the flush fixture with a fluorescent unit? Can't you just bring the wires down into the fluorescent housing through the knockout hole (same as with no box) and use the electrical box in the ceiling as nothing more than a pas-through for the Romex?

Or do you have to cut out the hole in the fluorescent fixture from knockout size up to a 3-1/2" box size, just to have the same single Romex wire come through it?

yes its code. if there is a box behind the fixture, there has to be a coutout the size of the box opening. Cant just poke the wires through a ko. Easiest way is to just run your romex directly into the fixture.