Electrical question...conduit versus in-wall wiring

[Rod Sheridan]

FYI, "conduit" is a generic term used for round raceway. The typical round metal tubing used as raceway is EMT - Electrical Metallic Tubing and has not threads. The EMT connectors are all screw fittings, where a set screw clamps down on the EMT.

There are other types of raceway that are allowable - non-metallic/PVC is another type. It comes in varying wall thicknesses - Schedule 40, Schedule 80, etc. that's the stuff you glue together.

Hi Rob, normally PVC is not used inside a building due to flame spread issues. I'd check with your local authority before using it inside a shop.

Regards, Rod.

[Michael Lutz]

I would go the conduit route. It makes it easier to make changes later. You can use PVC conduit indoors, but I would avoid using it anywhere it could get hit by an impact. EMT would be a better choice.

Mike

[Roland Chung]

Consider using a combination of romex and emt. Run 12-3 romex everywhere that you know you will ever want an outlet. Use 2 gang boxes everywhere with 1 outlet wired on each circuit. Put romex in the walls to every location where you know what you will be running and that you know what the requirements are (20a, 30a, etc). Put your known lighting electrical in the ceiling if you can.

Add another dedicated run of romex for every large 120v machine that you know you will have and that you know what the electrical requirements will be.

Flex is conduit and it can be easily installed inside of the walls before insulation and drywall. It will give you the best of both worlds - hidden in the walls (or exposed) and expandable (you can pull extra wires if your needs change). Flex can look sloppy on long exposed runs as it can sag between clamps. It is great inside of a wall. Consider using larger flex where you might need additional runs of larger wires - instead of multiple runs of flex or romex. Electrical materials are expensive - you may as well use only what you are sure that you need for now and expand only as you need to.

Since some of these wiring techniques may be new to you, have everything inspected. The inspector will help you catch any glaring mistakes before you cover your walls. If the idea of having everything inspected is intimidating to you - then hire an electrician and tell him how you would like things done (in general - like locations and # of circuits). He will offer professional advice and make sure that everything is done to code. Make sure that he pulls permits and is licensed and insured.

RC

[Eric Gustafson]

Metal Conduit allows you to use Multi strand wire. Multi. Strand carries more current.

This is not something I have ever heard. From my understanding, multistrand wire is just more flexible. 12 gauge solid should have the same capacity as 12 gauge stranded. I am not an electrician, however.

[Greg Funk]

This is not something I have ever heard. From my understanding, multistrand wire is just more flexible. 12 gauge solid should have the same capacity as 12 gauge stranded. I am not an electrician, however.

Correct. The difference between stranded and solid wire is negligible: 5.21 vs 5.32 ohm/km for 12 AWG.

Greg

[Chris Friesen]

Being in Wisconsin, I'm puzzled at why heating hasn't come into play. With every penetration through the walls and ceiling, heated air escapes (or cold air enters) the conditioned space.

I'm in Saskatchewan, Canada. The insulation has vapour barrier, and every outlet has a vapour barrier box around it sealed to the insulation vapour barrier. This is standard building code practice. I also caulked the holes in the vapour barrier boxes where the wires penetrate. There's no heating impact.

Something that nobody has mentioned yet is the fact that you start having to derate the conductors once you have multiple circuits in conduit. Granted, you can start at the full ampacity of the wire, but still once you have more than 7 or so conductors then you need to up the wire guage to compensate. This starts increasing costs.

[Randall Davis]

The EMT connectors are all screw fittings, where a set screw clamps down on the EMT.

Not all, if EMT is used outdoors a set screw connection is not permitted. In that case compresion fittings are used.

[Jim Becker]

My answer is...."Yes". I have both. In-wall for all the original shop circuits and some conduit down the walls for later modifications. I also have two drops that I did in conduit from the beginning and that allowed me to change the ciruits easily later as my machinery evolved. I think that conduit/raceway can be really convenient in a shop environment, although there obviously is a cost involved.

[Rob Russell]

Hi Rob, normally PVC is not used within a building due to flame spread issues. I'd check with your local building authority before using it inside a shop.

RNC (Rigid Nonmetallic Conduit) is listed for inside use. HDPE conduit is not. Based on the "Uses Permitted", it sounds like HDPE is really for underground use.

Rob The EMT connectors are all screw fittings, where a set screw clamps down on the EMT.

Not all, if EMT is used outdoors a set screw connection is not permitted. In that case compresion fittings are used.

True, but in the interests of not confusing issues, I left that out. Most of our workshops are indoors.

[Bruce Wrenn]

EMT is conduit threaded (rigid)is also conduit.
If you have a one man hobby shop save time and money put some thought in to your layout and use 12/2 romex for the general duty outlets. Wire your dust collecter, table saw, compresor to manufacterers specs. If your planer, jointer, drill press and table saw are all 240 volt save $ on breakers and panel space, run one 30 amp circuit to feed all of them unless you have figured a way to run two of these machines at the same time.

My copy of the NEC has them in two very seperate sections. Rigid is refered to as conduit, but EMT is refered to as strictlly EMT. Kinda like is it a concrete, or cement floor? Both are used interchangably, but only one is correct.

[Randall Davis]

My copy of the NEC has them in two very seperate sections. Rigid is refered to as conduit, but EMT is refered to as strictlly EMT. Kinda like is it a concrete, or cement floor? Both are used interchangably, but only one is correct.

They are very diffrent they are not necessarily used interchangably and they are both conduits. Conduit is also made of polyvinylchloride and other materials.

[Dan Clark]

EMT is conduit threaded (rigid)is also conduit.
If you have a one man hobby shop save time and money put some thought in to your layout and use 12/2 romex for the general duty outlets. Wire your dust collecter, table saw, compresor to manufacterers specs. If your planer, jointer, drill press and table saw are all 240 volt save $ on breakers and panel space, run one 30 amp circuit to feed all of them unless you have figured a way to run two of these machines at the same time.

Randall,

It turns out that I'm wrestling with the same issues in updating my garage/shop. For lights and other relatively permanent items, I agree with you. However...

While NEC 2005 allows you to go either way, for tools... I'm be concerned what happens when you change your mind. IF you have you workflow down pat (I don't) and IF you know the tools that you will be using for years to come (I don't), then fixed placement of Romex in walls is a great idea.

Right now, I use Festool tools a lot. They are portable and can be moved around easily. However, I expect to add more fixed tools like a bandsaw, drill press, maybe a small table saw, and jointer. OR, I might decide that Festool, Makita, Bosch, Hilti, or several of other good tool vendors has a better more flexible solution. And that's the problem - While some technology is fairly static, there are lots of new tools coming on the market that will displace current technology.

For example, there are multiple add-on rail systems for circular saws, routers, jig saws, and other tools. Festool is a big name in the built-in rail system market now. BUT, but Hilti and Makita have come out with some very nice tools to which they've added built-in rails.

For example, the new Makita SP6000K1 plunge saw is now available in Europe and the UK. It's a very nice looking saw and has built-in dust collection and attaches to a Makita guide rail. Add Makita quality and you've got a nice combo. This is brand new and a big change for Makita. But in a few years, I suspect that dust collection and built-in guide rails will be common-place in many great quality tools (this could give Festool fits ).

So what happens to your shop when you make a committment to one strategy now and then find better ways of doing things?

IMO, surface mounted electrical conduit is the way to go. The minimal extra expense in the short run will give you on-going benefits in terms flexibility and configurability. I'm going add extra circuits now (110 and 220) and stub them out to a surface-mount box. Then I can add or change the electrical configuration to suit my needs at any given time.

Regards,

Dan.

[Randall Davis]

Randall,

It turns out that I'm wrestling with the same issues in updating my garage/shop. For lights and other relatively permanent items, I agree with you. However...

While NEC 2005 allows you to go either way, for tools... I'm be concerned what happens when you change your mind. IF you have you workflow down pat (I don't) and IF you know the tools that you will be using for years to come (I don't), then fixed placement of Romex in walls is a great idea.

Right now, I use Festool tools a lot. They are portable and can be moved around easily. However, I expect to add more fixed tools like a bandsaw, drill press, maybe a small table saw, and jointer. OR, I might decide that Festool, Makita, Bosch, Hilti, or several of other good tool vendors has a better more flexible solution. And that's the problem - While some technology is fairly static, there are lots of new tools coming on the market that will displace current technology.

For example, there are multiple add-on rail systems for circular saws, routers, jig saws, and other tools. Festool is a big name in the built-in rail system market now. BUT, but Hilti and Makita have come out with some very nice tools to which they've added built-in rails.

For example, the new Makita SP6000K1 plunge saw is now available in Europe and the UK. It's a very nice looking saw and has built-in dust collection and attaches to a Makita guide rail. Add Makita quality and you've got a nice combo. This is brand new and a big change for Makita. But in a few years, I suspect that dust collection and built-in guide rails will be common-place in many great quality tools (this could give Festool fits ).

So what happens to your shop when you make a committment to one strategy now and then find better ways of doing things?

IMO, surface mounted electrical conduit is the way to go. The minimal extra expense in the short run will give you on-going benefits in terms flexibility and configurability. I'm going add extra circuits now (110 and 220) and stub them out to a surface-mount box. Then I can add or change the electrical configuration to suit my needs at any given time.

Regards,

Dan.

Dan, I understand your thought process, but isnt it true that you can add surface mounted conduit at any time in the future if needed?

[Charles Grosjean]

Another option is Wiremold 4000 series surface mount raceway. Looks much nicer than conduit/boxes, holds a lot of wire, derating rules are different (YMMV), extremely flexible and very easy to reconfigure. Wiremold makes plates/brackets for just about any device you might want. Fairly common in industrial applications.

http://www.wiremold.com/shared_content/pdf/ed531.pdf

[Rob Russell]

Another option is Wiremold 4000 series surface mount raceway ... derating rules are different (YMMV)

Why do you say that derating rules are different for Wiremold raceway? Is it classified as "Metal Wireway"?