Surface Mount Electrical questions

[purplezr2]

Working on finishing out my shop. I have done a bunch of home electrical that is concealed, but have never worked with conduit.

Have a few questions

I have read that stranded wire is easier to pull through conduit, any reason not to use stranded wire.

When is comes to boxes, there there seems to be two different corner styles squared ones and rounded ones, is there a large difference, any reason to go one way or the other? Round ones look a a little better.

Conduit connectors, thread bushing style vs snap lock, both have the set screw of the conduit. Seems the thread version might be slower but more robust.

 

[Lorydr]

Stranded wire will flow through any angled turns easier than solid. Include a pull-string with the conductors. Make sure the conduit is sized correctly for the amount of different gauge conductors. Plus possibly room to spare for any future wire pulls. That is all I have to offer.

 

[dscheidt]

Stranded wire is harder to terminate on devices that want a wire wrapped around a screw. In 12 and 14 AWG wire, solid is easier to work with if you're working alone, because it can often be pushed through conduit that's short and straight enough, which is much faster than a fish tape. Solid is also about 10% cheaper. 10 gauge, I can go either way, usually solid. 8 and larger are only in stranded.

Assuming you're talking about EMT, use either compression or set screw fittings, with a lock nut. Either style works fine, set screw tend to be a bit cheaper and are faster, compression tends to look a little better.
As for boxes, the difference is whether they're made by folding and welding the box, or drawing it out of a thicker plate. As you note, the drawn boxes look better, and are more resistant to damage (but this is probably not a real concern in a home shop). the drawn boxes tend to cost a bit more, and aren't available in as many sizes. Use what you like and can get

For outlets and switches, if you use crushed corner covers, and 'self grounding' devices that have a brass or copper spring contact on one of the mounting screws, you can avoid having to attach a grounding wire to them. That's totally worth the extra cost of the device.

 

[75gmck25]

And before the question comes up - Yes, you can pull standard NM-B through conduit. It won't go around corners well, and the jacket takes up a lot of space, but it is not prohibited by code.

Spend a little time studying the various metal boxes and the covers and devices to see your options.

You will find square metal boxes that use one screw on each opposite corner. You can use a flat metal cover that has screws on each corner if its just for a wire junction. However, you need to use a cover like this to mount receptacles (its sometimes listed as a mud ring. https://www.homedepot.com/p/Southwi...for-2-GFCI-Outlets-1-Pack-G1950-UPC/324472725

The other square metal boxes with rounded edges usually have threaded tabs near the middle so you can directly mount switches and receptacles, and then use standard wall plates. https://www.homedepot.com/p/Southwi...-3-4-KO-s-and-Four-CKO-s-MGSB-2-UPC/324509229

 

[mm08822]

'self grounding' devices that have a brass or copper spring contact on one of the mounting screws, you can avoid having to attach a grounding wire to them. That's totally worth the extra cost of the device.

For metal boxes surface mounted and raised covers, self-grounding devices are not required. Metal to metal contact between device yoke to raised cover to box is acceptable.

 

[PWC Repair]

Do you need all of it IN conduit? I ran almost all of my shop in armored cable........WAY easier.

 

[Snapped-off]

Do you need all of it IN conduit? I ran almost all of my shop in armored cable........WAY easier.

Is it susceptible to damage?

 

[mike93lx]

Do you need all of it IN conduit? I ran almost all of my shop in armored cable........WAY easier.

Armored cable has the same protection requirements as NM

 

[CoogarXR]

Do you need all of it IN conduit? I ran almost all of my shop in armored cable........WAY easier.

How was the cost comparison? I wonder about the cost of armored cable vs flex conduit and individual conductors. I realize I could look it up, but I'm lazy.

 

[PWC Repair]

How was the cost comparison? I wonder about the cost of armored cable vs flex conduit and individual conductors. I realize I could look it up, but I'm lazy.

When I did mine the 'MC' cable was CHEAPER than buying the conduit seperately........not to mention much less hassle.

 

[CoogarXR]

When I did mine the 'MC' cable was CHEAPER than buying the conduit seperately........not to mention much less hassle.

Thanks for that insight. I have to wire my barn eventually, and I was considering MC. Now I'm really considering it, lol

 

[Crazyjake8493]

When I did mine the 'MC' cable was CHEAPER than buying the conduit seperately........not to mention much less hassle.

Exposed MC never looks as good as EMT - tough to get nice straight long runs, especially horizontal.

To each their own though. As long as one is happy with it in their own garage, that's all that matters.

 

[alfredeneuman]

All flex conduits, MC and AC cables share the same "protection from physical damage" rule as NM (Romex).
You might as well use Romex as any of these
The conduit fill rules for Romex are outlandish = 3/4 EMT with 3#12s
Choose individual conductors if you use EMT

 

[dscheidt]

Exposed MC never looks as good as EMT - tough to get nice straight long runs, especially horizontal.

To each their own though. As long as one is happy with it in their own garage, that's all that matters.

Exposed MC also screams hack installation, either by someone who doesn’t know (or doesn’t care ) that it needs to be protected from damage (and if it doesn’t need to be, why aren’t they using NM?) or they can’t be bothered to run emt. Short whips to lights are okay, but I would rather see FMC. Material cost for EMT is lower than for MC, drastically lower where one pipe can can carry more than two wires. Difference in labor depends on how it is run, and how skilled the labor is.

EMT also provides much more flexibility for future changes. (And I make all sorts of little changes because of the conduit that I would never do if it were MC or NM, so this is a real thing, at least in some cases.).

 

[PWC Repair]

- tough to get nice straight long runs, especially horizontal.

True. A couple pics of mine around the shop. Junction boxes that branch out to office and lights. I made it look as good as possible. Which was good enough for my shop.

 

[dscheidt]

When I did mine the 'MC' cable was CHEAPER than buying the conduit seperately........not to mention much less hassle.

How was the cost comparison? I wonder about the cost of armored cable vs flex conduit and individual conductors. I realize I could look it up, but I'm lazy.

Flexible metal conduit is probably a bit more expensive than MC, for two conductors in 12 or 14 awg. When you add more wire to the FMC, or larger wires, FMC comes out ahead. And FMC can have wires added or removed in the future.

EMT is cheaper than either, but it is more work. Looks much better, as well.

 

[Crazyjake8493]

True. A couple pics of mine around the shop. Junction boxes that branch out to office and lights. I made it look as good as possible. Which was good enough for my shop.

Looks good enough to me. If you pull it tight and use enough straps it can look good.

 

[Crazyjake8493]

Exposed MC also screams hack installation, either by someone who doesn’t know (or doesn’t care ) that it needs to be protected from damage (and if it doesn’t need to be, why aren’t they using NM?) or they can’t be bothered to run emt. Short whips to lights are okay, but I would rather see FMC. Material cost for EMT is lower than for MC, drastically lower where one pipe can can carry more than two wires. Difference in labor depends on how it is run, and how skilled the labor is.

EMT also provides much more flexibility for future changes. (And I make all sorts of little changes because of the conduit that I would never do if it were MC or NM, so this is a real thing, at least in some cases.).

I totally agree. To me, EMT is worth the additional time for install for all those reasons - craftsmanship, protection, and flexibility.