Code for wires / outlet / switch boxes in an open framed barn?

[TimberMan]

I have decided to electrify the barn that i am building and although the structure is agricultural except, if i electrify it i need to follow electrical code.

I plan to leave the barn open framed and uninsulated and would typically just rough in the electrical like in a home, install the outlets, switches, cover plates and call it a day but i am not sure if that meets code.

Can anyone point me in the right direction so i can figure out if my plan would work or if i need conduit, or surface mount boxes or something else?

Thx!

 

[PCustoms]

Wire must be protected from damage, so that's either conduit or nm-b properly routed (i.e. through studs behind sheathing).

 

[Chuckster in NJ]

I suggest wiring the barn for agricultural use because the next owner may use it for animals……… It may cost a little more now but it is an investment for the future.
See NEC article 547 on what is required.

 

[BreeStephany]

I would use either MC cable or conduit and then use deep 4sq. boxes and industrial raised covers at all receptacle and switch locations.

MC cable is quick and easy to install, pretty much like romex, except using straps rather than staples, and adding anti-shorts and connectors after stripping the cable.

 

[PCustoms]

I would use either MC cable or conduit and then use deep 4sq. boxes and industrial raised covers at all receptacle and switch locations.

MC cable is quick and easy to install, pretty much like romex, except using straps rather than staples, and adding anti-shorts and connectors after stripping the cable.

Doesn't MC cable require the same protection from damage as NM-B?

 

[Chuckster in NJ]

READ NEC 547……….. It’s only three pages.

 

[sparky 1971]

I have decided to electrify the barn that i am building and although the structure is agricultural except, if i electrify it i need to follow electrical code
I plan to leave the barn open framed and uninsulated and would typically just rough in the electrical like in a home, install the outlets, switches, cover plates and call it a day but i am not sure if that meets code.

Can anyone point me in the right direction so i can figure out if my plan would work or if i need conduit, or surface mount boxes or something else?

Thx!

The main things are going to be receptacles GFCI protected as well as the wiring has to be protected from physical damage. Since there is no definition of protected from physical damage, it's up the the AHJ and unless we know where you are at and someone on here just happens to know what is required in that location, nobody will be able to answer it for you. Just call an inspector for your area, even if you are ag exempt, they can still tell you what is expected. Most of the areas I work would require it to be in some type of conduit, however, there is at least one area that would allow exposed romex as long as it wasn't run horizontal below a certain height (8'? maybe) I don't know and don't really care what the exact height requirement is because I would automatically be using EMT and that is the way I would suggest it be done.

 

[u2slow]

If OP is in Canada, exposed cables are often protected by elevation alone. 5'-up is allowed in many cases.

 

[mike93lx]

Asking about code compliance without specifying a location wastes a lot of time

Please out your location (at least state) in your profile

 

[sparky 1971]

Doesn't MC cable require the same protection from damage as NM-B?

Yes but "protection" isn't defined. What might not pass an inspection according to one AHJ might be satisfactory to another. I work in several jurisdictions and the requirements run from metal conduit down to exposed romex is fine as long as the horizontal runs are above a certain height. I just automatically default to EMT, but have lost out on at least a couple of jobs because of it.

 

[TimberMan]

Asking about code compliance without specifying a location wastes a lot of time

Please out your location (at least state) in your profile

I am in North Carolina

 

[mike93lx]

I am in North Carolina

Thanks. If you look in "account details" after clicking on your user icon at the top, you can add that in so people can see it for future questions.

 

[sparky 1971]

Asking about code compliance without specifying a location wastes a lot of time

Please out your location (at least state) in your profile

Fun hater. If it weren't for you I could have had the barn done using stainless steel rigid and explosion proof boxes and fixtures. Which, I might add would almost certainly be code compliant with no concerns about meeting the minimum requirements set forth by the NEC, leaving the only question to be what size wire for the welder and air compressor.

 

[mike93lx]

Fun hater. If it weren't for you I could have had the barn done using stainless steel rigid and explosion proof boxes and fixtures. Which, I might add would almost certainly be code compliant with no concerns about meeting the minimum requirements set forth by the NEC, leaving the only question to be what size wire for the welder and air compressor.

Lol. Sorry bud.

 

[sparky 1971]

I am in North Carolina

Looks like NC is on the 2020, but remains on the 2017 for one and two family dwellings. That's good, you shouldn't have to worry about the ridiculous requirement for GFCI protection for 240 volt receptacles in a garage, within 6' of a sink and outdoor outlets. Just find out who would be the inspector for your area if you were building a house and make a phone call. Around here, they would be more than willing to answer any questions and would probably stop by and take a look.

 

[u2slow]

In a barn, you may want to consider rodent protection. That would rule out NM cable types.

A common 'fix' around here for roughed-in electrical that never ends up with the walls finished.... is to run one pass of 4' sheathing/boarding for protection. (1' above floor) That gets you protected up to 5' where elevation may take over.

 

[reader2580]

Detached garage wiring with NM-B leaves me perplexed. My current detached garage with eight foot walls I put in a new panel (in a new location) so I ran new cable to where the circuits had previously started. I also added some new receptacles at around 42" high. The new NM-B was run through the exposed studs at most 48" high. This was all inspected under the 2104 NEC and passed.

I built a new 24x60 garage with sixteen foot walls this year, but there is zero electrical yet. Let's say I put receptacles at 42" and NM-B around 48" through the studs to feed the receptacles. Is this allowed under 2023 NEC if the walls will be left open? I haven't been able to get a straight answer on what is allowed. I haven't tried to contact the inspector yet.

 

[sparky 1971]

Detached garage wiring with NM-B leaves me perplexed. My current detached garage with eight foot walls I put in a new panel (in a new location) so I ran new cable to where the circuits had previously started. I also added some new receptacles at around 42" high. The new NM-B was run through the exposed studs at most 48" high. This was all inspected under the 2104 NEC and passed.

I built a new 24x60 garage with sixteen foot walls this year, but there is zero electrical yet. Let's say I put receptacles at 42" and NM-B around 48" through the studs to feed the receptacles. Is this allowed under 2023 NEC if the walls will be left open? I haven't been able to get a straight answer on what is allowed. I haven't tried to contact the inspector yet.

All editions of the NEC going back to at least 1993, which is the cycle we were on when I started, state that romex has to be protected from physical damage. Since there is no definition of what that is, it is up to the AHJ, and if they don't have a definition, it's going to be up to the discretion of the inspector. One guy might say it's protected well enough, another will say "ain't no way that's protected, do something about it". You will have to make a call to the specific building department and ask.

One of my AHJ's requires metal conduit so I just run with that everywhere the walls won't be finished no matter the location.

 

[mm08822]

Detached garage wiring with NM-B leaves me perplexed. My current detached garage with eight foot walls I put in a new panel (in a new location) so I ran new cable to where the circuits had previously started. I also added some new receptacles at around 42" high. The new NM-B was run through the exposed studs at most 48" high. This was all inspected under the 2104 NEC and passed.

I built a new 24x60 garage with sixteen foot walls this year, but there is zero electrical yet. Let's say I put receptacles at 42" and NM-B around 48" through the studs to feed the receptacles. Is this allowed under 2023 NEC if the walls will be left open? I haven't been able to get a straight answer on what is allowed. I haven't tried to contact the inspector yet.

As Sparky said.....one AHJ says it's ok and another fails it. It's a matter of who's doing the inspection and which side of the bed they woke up on.

Call first, get the current organ grinder's opinion.......it ***** having to re-do perfectly good work.

 

[reader2580]

As Sparky said.....one AHJ says it's ok and another fails it. It's a matter of who's doing the inspection and which side of the bed they woke up on.

Call first, get the current organ grinder's opinion.......it ***** having to re-do perfectly good work.

I emailed the electrical inspector and he said that vertical runs of NM-B are okay, but horizontal runs are not, unless runner boards are used. Vertical runs with 16 foot walls would use up cable at an alarming rate. I am going to call him tomorrow as I have a few other questions. I am guessing MC cable is also vertical only as the NEC says it needs protection too.

EMT in a garage seems like total overkill. I also think it looks pretty silly to run EMT horizontally across exposed studs. I would think the EMT over time would be subject to getting dents and bends in it, but at least the wire wouldn't get damaged. EMT and THHN is quite a bit more expensive and labor intensive than NM-B. I would need to practice bending conduit quite a bit before trying this.

My garage project has cost at least ten thousand dollars more than planned so my bank account is at rock bottom. I need to do the basic wiring for as little cost as possible. I still need to spend about $2,000 more in lift rental, building materials, and electrical supplies to get the project to the finish line this spring.

 

[mike93lx]

I emailed the electrical inspector and he said that vertical runs of NM-B are okay, but horizontal runs are not, unless runner boards are used. Vertical runs with 16 foot walls would use up cable at an alarming rate. I am going to call him tomorrow as I have a few other questions. I am guessing MC cable is also vertical only as the NEC says it needs protection too.

EMT in a garage seems like total overkill. I also think it looks pretty silly to run EMT horizontally across exposed studs. I would think the EMT over time would be subject to getting dents and bends in it, but at least the wire wouldn't get damaged. EMT and THHN is quite a bit more expensive and labor intensive than NM-B. I would need to practice bending conduit quite a bit before trying this.

My garage project has cost at least ten thousand dollars more than planned so my bank account is at rock bottom. I need to do the basic wiring for as little cost as possible. I still need to spend about $2,000 more in lift rental, building materials, and electrical supplies to get the project to the finish line this spring.

Install 3/4 plywood blocking to cover the wire flush with the outside plane of the wall studs. Pocket screws would make it fast and easy

 

[mm08822]

Ask if bored holes are acceptable with a running board as a shield on the surface of the studs.

 

[mike93lx]

Ask if bored holes are acceptable with a running board as a shield on the surface of the studs.

Why wouldn't it be? It's the same as what it would be if the walls were dry walled, no?

 

[sparky 1971]

Why wouldn't it be? It's the same as what it would be if the walls were dry walled, no?

Because if the plywood is only on the face, they could say something could fall over the top and land on the cable. This protected from damage **** needs to be addressed in the code book so everyone is on the same page. It'll never happen, they are too busy shoving AFCI/GFCI/TR garbage down our throats. Maybe if big plywood could get involved in the code making process...

 

[mm08822]

Why wouldn't it be? It's the same as what it would be if the walls were dry walled, no?

I expect it should be fine, but ask AHJ.

 

[mm08822]

Because if the plywood is only on the face, they could say something could fall over the top and land on the cable. This protected from damage **** needs to be addressed in the code book so everyone is on the same page. It'll never happen, they are too busy shoving AFCI/GFCI/TR garbage down our throats. Maybe if big plywood could get involved in the code making process...

They can all play the worst case game is always possible. This is why you ask first.

 

[sparky 1971]

They can all play the worst case game is always possible. This is why you ask first.

In cases like this, I just break out the bender and run EMT. I work in at least five different jurisdictions and one of them requires everything in a garage with uncovered walls to be in metal conduit so I just run with it everywhere.

 

[mm08822]

In cases like this, I just break out the bender and run EMT. I work in at least five different jurisdictions and one of them requires everything in a garage with uncovered walls to be in metal conduit so I just run with it everywhere.

While that makes for a great looking job, it can price you out of getting the job if others are doing less.

 

[Metal-Marc]

EMT in a garage seems like total overkill.

That's why you need EMT in a garage.

 

[sparky 1971]

While that makes for a great looking job, it can price you out of getting the job if others are doing less.

I'm one of the lucky ones in that since I don't have to worry about keeping others busy, I have more than enough to keep me going so I don't care. If someone's looking for a hard figure, I don't bother even looking at it. If I had employees to worry about, it would be a different story.

 

[reader2580]

I talked to the electrical inspector this morning. MC cable and NM-B cables are subject to the same protection requirements as I expected. The requirement for horizontal runs in exposed stud walls is to put a block between the studs and staple the cable to the bottom of the block.

I think a lot of this stuff is going to be standardized state wide and not left up to the individual inspector anymore. Electrical inspectors used to be independent contractors working for the state. The state recently made all electrical inspectors state employees so I would expect they are all going to be working from the same playbook for stuff that is determined by the AHJ.

 

[mike93lx]

I talked to the electrical inspector this morning. MC cable and NM-B cables are subject to the same protection requirements as I expected. The requirement for horizontal runs in exposed stud walls is to put a block between the studs and staple the cable to the bottom of the block.

I think a lot of this stuff is going to be standardized state wide and not left up to the individual inspector anymore. Electrical inspectors used to be independent contractors working for the state. The state recently made all electrical inspectors state employees so I would expect they are all going to be working from the same playbook for stuff that is determined by the AHJ.

Well, that's at least a lot easier and cheaper than conduit

 

[TimberMan]

I talked to the electrical inspector this morning. MC cable and NM-B cables are subject to the same protection requirements as I expected. The requirement for horizontal runs in exposed stud walls is to put a block between the studs and staple the cable to the bottom of the block.

I think a lot of this stuff is going to be standardized state wide and not left up to the individual inspector anymore. Electrical inspectors used to be independent contractors working for the state. The state recently made all electrical inspectors state employees so I would expect they are all going to be working from the same playbook for stuff that is determined by the AHJ.

I am going to see if my head inspector will accept this as protected…definately the cheapest, easiest and future proof if I ever want to insulate or sheathe the inside of the barn. Thx!

 

[75gmck25]

In many cases for inspection you only need to install one interior and one exterior light, with switches, and at least one GFCI receptacle. Install it all according to the inspector's guidance and then get your permit approved. After that its whatever you want to do to safely expand your electrical setup. Saves a lot of money up front if you are short of cash - just tell them you are too broke to do more (which may apparently be true).