Garage Electrical Wiring
Allowable Electrical Wiring Methods
The photos on this page show how the electrical wiring was installed prior to inspection. After the inspection took place the walls were insulated and sheet rock was installed. If the walls were to be left open then Romex type wiring would not be allowed to be installed because the wiring would be exposed making it vulnerable to damage. When the walls will remain open, approved conduits may be used to protect the electrical wiring. Electrical Conduit such as flex and EMT could be installed along with metal junction boxes.
Electrician and Detached Garage Project
Cable Size for a Garage Sub-Panel
Question from Ko:
Electrician and Detached Garage Project.
I have a remodel on a detached garage (with living area above), the underground conduit is 3/4 in. PVC. It has a run of 53', with 4 inch radius bend (90 deg) at both ends. What is the largest set of cables known to pull through 3/4 inch PVC to feed a sub-panel (hot/hot/neutral/ground)?
I'm estimating #6 for both legs and neutral and #8 for ground.
Ko, it sounds like you may be limited to #6's and #8's Copper THW/THWN. The PVC size and number of bends could be a problem. Use lots of wire lubricant.
The lesson here is to always up-size your PVC conduit. PVC is inexpensive so plan ahead while the trench is open!
For more information about conduit fill:
Locating the Problem in an Electrical Circuit
I added a few lights, switches, and outlets in my garage. There were two power sources. One was from an existing three-panel switch that ran all over. Everything worked A-Okay with that.
But I blew it with the other line. It was originally feeding only two outlets: one on the ceiling next to the garage door opener (that plugged into it), and the other outlet was a breaker (GFI?) on the back wall. My plan was to tap into this line for three lights and three outlets (the original two plus one more). But when I was ready to test it one switch was not yet installed but the wires were in place wrapped together (and stripped). So it shorted out. After I separated the wires, I reset the breaker with no power. I turned off the main power and went into the panel and switched the black wire from the line to a breaker I knew was working and still nothing. Is it possible the wires were damaged?
Thanks for any advice you can give.
Ed in De Land Florida
Ed, it is very possible that when you restore power to the circuit that there is electricity up to a point where a connection has blown apart, so be very careful. This is where a Tick type Voltage Tester comes in handy so you are able to see where the voltage is and where it stops, which will most likely give a clear indication of the location of the problem.
Power for a Garage Electrical Panel
Michael, from Polson, Montana asks:
I have a Cutler Hammer main electrical panel. I want to add another 100A breaker for my garage panel. There doesn't seem to be a space in the panel to plug in another breaker. Am I going to have to replace the panel, or am I missing something?
Michael, Depending on the exact Cutlet Hammer panel that you have, it may be possible to swap out a few full size circuit breakers and replace them with tandem circuit breakers which would free up the required space for the 100 amp circuit breaker for the garage panel.
Static From Electronic Light Fixture Ballast
I installed a new electronic ballast in fluorescent fixture. My radio now has static on it. How can I stop it?
Hi Jody, yes some of these light fixtures do produce line noise, especially the economy Shop Light Fixtures. First, make sure the fixture is grounded. Then get yourself a plug strip that has built in line nose suppression and conditioning which should eliminate the line noise. Keep in mind that the noise may be transmitting right into the antenna signal as well. If this is the case, you may need to upgrade the fixture to a better brand.
More about Conditioned Plug Strips
Questions about Garage Electrical Wiring
Question from JD, a Homeowner in Northern California:
Should I use GFCI Ground Fault or ARC Fault Breakers in my Garage?
Next spring we will be remodeling and expanding an attached garage in a residential house. It will be a retirement hobby cave. All the plugs will be full 20 AMP with #10 wire. I have used Buchanan electrical crimpers with sleeves and caps in the past. I like them more than twist on wire nuts.
My problem is that I have a whole shop full, at my place in the city, not my future retirement place to be remodeled, of 1930’s and 1940’s shop equipment that I fully restored. If any of this equipment is on a Ground Fault or ARC Fault circuit, the old motors will pop the circuit off every time.
I know that the old code allowed for “straight” plugs for years in garages because people screamed about their old refrigerator or freezers tripping these circuits, I even read that in the background reference material for the old code development.
But since most of that old stuff has been replaced in the last 25 years the NEC code people added the garages to the ground-arc fault way of doing things.
The problem is for folks like me. So, do I have to play the game and replace everything after the work is done? Should I use GFCI Ground Fault or ARC Fault breakers then just swap them out?
I will be darned if I will change every electric motor on my restored equipment.
GFCI Ground Fault Protection for Garage Circuits
JD, I hear where your coming from, however I would give the newer ARC Fault and GFCI outlets and circuit breakers a try. I too remember when these new devices came out there were a lot of nuisance tripping that was occurring, but there have been several improvements that have made these devices much more reliable. While working in a garage with a grounded concrete floor it is essential to have GFCI protection, especially when using older non insulated metal frame motors and equipment. If your older motors continue to trip a GFCI then I would encourage you to perform some continuity tests on the motors and replace any worn out cloth wiring, or cracked insulated wires with new wire. I also have a collection of older electrical equipment that I will hang onto for at least a display board of old-time electrical history.
Screw-on Wire Connectors vs the old style Buchanan Crimp and Sleeve Connections
After working several years in the electrical field, and working with thousands of questions about the subject, it is a fact that expansion and contraction of metal electrical circuit components will contribute to a loose connection, which will lead to an electrical connection failure, and damaged equipment. So as much as the crimp type connector has been a popular product I am in favor of using a screw on type wire connector for the smaller amperage circuit connections, especially the types with an internal spring which will flex with temperature fluctuation. Having said this, I do use crimp products for larger wire with the Approved Crimp Tool which ensures a tight crimp and good connection. We see the crimp type of wire connectors widely used in the industry, however the only way these connections can be made reliable is when using a Quad-Indent Crimp Tool and Dielectric Grease as required for the application.
Be safe and enjoy your new garage project!