Conduit Size & Type Selection + Other Conduit Q's

[Spudland_Dave]

Gettin ready to put my Sub in...using qty 4 of the 4ga THHN I have. Using this chart: http://www.westernextralite.com/resources.asp?key=47 1" EMT should be fine...but at max. Should I go with 1" being at max, or would you go with 1.25" for the heck of it.

Is it OK to mix & match conduit? meaning can I use standard EMT where feasible...use a 2' piece of Flex where needed, back to EMT for a stretch, back 'nuther Flex piece where needed...etc...

EMT/Conduit as a whole in Walls...will be insulated & sheetrocked. I've read numerous comments about derating cables and what have you, do I need to think about derating? Conduit will go up from my current 100A Panel, up into the attic...Winter time means wicked cold up there, summers, bit hotter

 

[madosta]

Conduit is cheap. Definitely run a larger conduit to the sub-panel, it will save you time and headache.

 

[rburke65]

How far are you pulling this wire? For the cost of PVC conduit, you will not kick yourself in your a** if you run 2". Trust me when I tell you, you will never hear someone say, "Damn, I wish I had run smaller conduit!"

 

[Spudland_Dave]

How far are you pulling this wire? For the cost of PVC conduit, you will not kick yourself in your a** if you run 2". Trust me when I tell you, you will never hear someone say, "Damn, I wish I had run smaller conduit!"

Approximately 65' total length (thats the estimate of how much conduit I need....reality might be a few feet less)

Problem with going big is I need to drill a hole in my top plate to get the conduit thru....Hate to go too big, already got 8 or 9 1" holes in it, and on the wall with the 2nd panel, i've only got 2.5" Max to work with. Mind you, its not a structural wall, so I can use the full 2.5"
With an OD of 1.900", thats about max size I'd feel comfortable drilling actually in my structural wall... if it werent for transitioning sizes and such, I'd probably go 1" straight up thru the top plate and go with 1.5" the rest of the way.

 

[Charles (in GA)]

Mixing conduit types generally looks hack to anyone who inspects the installation. Real problem is that the EMT needs to be grounded. You don't want a section of EMT with PVC on either end of it, if you did, you would need to properly ground the EMT section.

Other issue with that size metal is you will need to use prebent sections coupled together, unless you know a professional commercial electrician who has a power bender.

Charles

 

[frankush]

Don't mix and match. That's the sign of a true amateur. Run 1-1/4". You can still bend it with a hand bender and won't need to rent a large bender. The larger conduit will make the pull easier. Depending on the install, you may be able to do it with prefabbed 90's.

 

[Spudland_Dave]

Other issue with that size metal is you will need to use prebent sections coupled together, unless you know a professional commercial electrician who has a power bender.

Charles

I do know a few...thing is, will I get things bent when I want to...Kinda hoping/thinkin of installing this weekend.

Don't mix and match. That's the sign of a true amateur. Run 1-1/4". You can still bend it with a hand bender and won't need to rent a large bender. The larger conduit will make the pull easier. Depending on the install, you may be able to do it with prefabbed 90's.

Didnt think of that...once you said it, Its completely out, I'd like it to look nice. So 1.25" is bendable by hand....thats an option then, borrowing a hand bender is going to be a bit easier I think.

Any issues with condensation and EMT if I'm in an insulated wall and it will poke up thru the insulation into un-insulated, unheated area...aka Attic space?

Didnt think of PVC conduit...might go that way I guess.

 

[frankush]

You'll have to put some "***" into it with a hand bender. Steady foot pressure is a must or you'll kink the hell out of it. Condensation shouldn't be an issue, but duct seal is available from any electrical supply house. You might find this interesting.

 

[Highbeam]

You say you are running 4 wires for a subpanel. Well, two hots, a neutral and a ground right? The ground does not need to be full size. Save yourself some money and make pulling it easier by downsizing that ground.

I pulled 3 - 6 gauge THWNs plus the ground which I believe was 10 gauge and I used 1.5" conduit. Always go bigger than you need and I of course used plastic. Nobody around here uses EMT in the ground. Plenty of bends are available to allow you to get the conduit in place. Cut and glue with no special tools. All plastic so it is insulated.

 

[Spudland_Dave]

You say you are running 4 wires for a subpanel. Well, two hots, a neutral and a ground right? The ground does not need to be full size. Save yourself some money and make pulling it easier by downsizing that ground.

Already got all 4 conductors...cost me a Dunkin Donut's coffee...so even if I bought a new ground conductor, i'd spend more on it then I did all 300' (4 conductors, 75' ea) of cable.

if I had a use for a single 75' piece of 4ga THHN...I might consider it.