I have a small barn that I want to add a few 220v 50 amp outlets in soon. Are there any safety concerns or disadvantages to using pvc conduit? The conduit will be under roof in a non climate control ed building.

Its cheaper. I used it in my basement.. Just make sure you go big enough so you aren't fighting it as you pull the wires.


With steel you can shape custom radii but need to buy the tool.




And you shouldn't sent a Romex type wire thru there, use the individual wires your going to want some pull elbows to make your life easier.

Why not just run MC cable (metal clad cable, sometimes called BX) it will provide a level of protection romex will not and will be much less time consuming than conduit.

ETA: just curious but what are you running outlets for that requires 50A?

That MC cable sounds like an option. I'm leaning more towards conduit just to have more options of running additional power outlets along the as I acquire more machines. I want to put in a 50a line for an additional welder outlet and probably a 3 phase converter down the road, I also need a line to run a 220v 22a air compressor; I still need to look in to what size wire to run and what breaker to use on the air compressor though.

you will need 10-2 for the air compressor. I would use M/C cable and be done.

Price it out both ways. The electrical supply house I got my wire from was actually cheaper than Lowes..

If the compressor is 22 amps you probably will want to use a 30 amp breaker.

Check your local recycling/salvage yard, that's where I have been buying all my wire recently.  I picked up a new 1000' roll of 12/2 for almost $75 cheaper than I could have gotten it at Lowe's, and have also found very good deals on 6w3 and 8w3 Romex (all for less than $1/ft).  Even found some 6w4 SOOW cable for $1/ft, much cheaper than you will find it anywhere else.

The current 'rating' of the motor has nothing to do with anything.
The table is in the electric motor article 430 of the NEC and is based on full running horsepower marked on the motor nameplate.
Period and nothing else.
120% of motor FLR from the table for wire size.
Breaker can be larger as required for starting current. Possibly by a couple hundred %.
You will be using a thermal-magnetic breaker.  Magnetic only breakers go up to 700% over FLR.

Just run a sub panel, no real reason to run a bunch of separate circuits.

No live stock in the barn correct? Ran PVC for a similar project for a friend, a general barn workshop, A couple of years later he converted a section to a stable for a horse and it chewed the PVC.  He was smart enough to turn off the dedicated breaker for that conduit run so the horse was fine. Ended up cutting it back to ceiling height and re running to the smaller shop area. The funny thing is that the more kids he has the smaller the shop gets.

I like working with PVC. Easy to cut, glue, etc. and I feel more comfortable having it in places where it might get rained on. I know you can you metallic conduit as a ground though, so there's that. Oh, yeah, don't run Romex through conduit. That was a stupid mistake. I also hadn't read up on conduit fill charts when I did that. Guess how I spent my afternoon?

This man knows his shit.
Beat me to it.

PVC needs a lot more support. Every 4' as opposed to every 10" with any metal conduit.
Pvc also need room for expansion. expansion joints are needed for some runs or the pipe will expand in the heat and look like spaghetti, or shrink in the winter and break the joints.

Current has everything to do with the breaker and wire size. The breaker should be as close to the full load amps as possible and still handle the startup. Wire is sized at 125% (article 430.22) of the full load amps, not 120%. I'm not sure what FLR means as mentioned by someone else. Should be FLA. If not subject to damage, run romex. Faster and cheaper.

You may even need a higher current, time delay breaker.  Read the directions.

Try reading the rest of the article.
FLR means Full Load Rating and comes from the table in 430 based only on horsepower.

FLA is  motor label BS that means NOTHING and is not used.

PVC is not allowed if subject to even moderate damage.
Read the Code section for rigid non-metallic conduit.
EMT is not all that tough either.
AC is even lower.
The NM rules apply to AC for protection.
Read the separate articles. Many cross back to the NM article for physical protection.

The breaker is allowed to be as large as required for start up.
There is no requirement it be "as close to the full load amps as possible."
You can get and idea of what a starting surge will be using the kV-A locked rotor code on the motor and the horsepower.
Startup is a 'locked rotor' condition. Nothing is turning yet.
The kV-A locked rotor letter to number table is in Article 430.

Motors have thermal overload built in and cannot overload wires sized correctly.
All the breaker is for is feeder protection to the motor against short circuits in the feeder.

FLA is the actual running load of the motor. I agree that the tables in the code book can be used to size the conductors, FLA is a more accurate rating. I've glanced thru the code book and I can't seem to find FLR. The tables say full load current in amperes Can you give me the page it is on. As for the type conductors, it's a barn. Romex is perfectly fine unless he thinks a cow is going to eat it. Today's breakers can handle the split second startup and the closer to the full load amps of the motor, the better protected it it.

make sure you properly size the conduit for the conductors you're pulling.
just because it fits, doesn't mean it wont melt the conduit..

The most common breaker type is an inverse time thermal magnetic.
Depending on the kV-A starting load of the motor and any loads present when power is applied you may need a breaker far larger than you would think.
A smaller breaker has no affect on safety of anything.
The breaker is there for short circuit protection of the motor feeds and nothing else.
The motor internal thermal over load protection is what protects it.

Making sure that the voltage does not dip excessively under start up is how you make sure a motor will have a long life.
Higher voltage (240 V vs. 120 V) allows smaller currents and reduces drop in the lines on startup surge.