Electrical conduit - finding 3 way elbows, load strengh

14 years ago

Hello!

I'd like to use electrical conduit to build structures that support tall plants and for vines to grow up. My plan is to use these with raised beds, usually four feet wide and constructed of wood.

I have several questions that are related to each other.

First, how much of a load can horizontally placed steel electrical conduit support? (I realize this depends on the diameter, length, etc. I did a Google search on this but everyone wants to talk about electrical load in amps, not how much weight it can support. Does anyone know where of some tables online where I can look this up?)

Second, does anyone know where to get a 3 way elbow junction for steel electrical conduit? (To explain what I mean, this is what you'd want to have at each corner if you decided to build a box out of the conduit.)

Related to this, how much load-bearing strength will electrical conduit lose if I put a 90 degree bend in it instead of cutting it in two and putting a 90 degree elbow where I want to have the corner? (Any tips on maintaining as much strength as possible? Don't make the radius of the turn too sharp I would guess...)

Finally, does anyone know where I can get a strap or something of that nature that will let me attach the end of a piece of electrical conduit to the middle of another piece of electrical conduit, with the end piece being attached coming off of the other piece at a 90 degree angle? (Other angles such as 45 degrees might also be of interest.) To clarify, my purpose here is to be able to have a horizontal piece of electrical conduit attach to a vertical piece of electrical conduit in order to brace it and help prevent it from falling over when the vertical piece is subject to a substantial sideways load (e.g. the wind blows really hard against the plants growing up the vertical piece).

Oh, one more comment - although electrical conduit is pretty cheap, some of the fittings (e.g. 90 degree elbows) cost more and can add up pretty quickly if you're going to be using a number of them. If anyone has some good ideas for keeping down the costs for the kinds of things I'm talking about, I'd be very interested in hearing about them.

Thanks!

Featured Answer

eric_wa

14 years ago

Dan,

I rifled through your pictures. Hope you don't mind. Do you have a link that describes you soil tubes / coldframe setup. Is it hooked up to a hotwater tank? I don't want to highjack this post, so maybe you can start a new one.

Eric

Comments (9)

eric_wa
14 years ago
knox,

The link below is one of many conduit fittings for canopies sites. They are not cheap.

Here is a link that might be useful: Canopy fittings
Dan _Staley (5b Sunset 2B AHS 7)
14 years ago
I use 1/2 and 3/4 in EMT for all my trellises. I grow toms, cukes, butternuts on them zero problem.

You don't need expensive fittings, simply get a pipe bender and bend to a 90Âº then connect with a straight coupler. No problem. Mine are anchored in the ground either with rebar or a PVC sleeve. You don't need any of that complicated stuff you imply above. I suspect my winds here are higher than yours as well, and more constant. you can see mine (or not see as I painted them to blend in). I connect them with zip ties. One 1/2 in trellis, 8ft wide, should cost you with rebar and connectors, about US$9.00 right now. And you'll get an extra length of conduit to do something with.

Dan
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Dan _Staley (5b Sunset 2B AHS 7)
14 years ago
Eric,

real quick, I'm testing the heating tubes for a patent, so I'll have to be vague, but I heat water inside the coldframe and it circulates thru the soil; not sure I have the best design this year and will re-work for next year. I have a buddy in Wenatchee area that heats 2-40 gal barrels with a solar panel and circulates water thru tubes with a solar fountain pump, his GH is ~2/3 of your size. You can contact me offline if you wish.

Dan
knoxvillegardener
Original Author
14 years ago
Dan,

Thanks for the info!

A question - Would you mind providing a link to a picture of a straight coupler at a website that sells them?

Although I think I know what you are are talking about, I am not 100% sure. Googling "straight coupler electrical conduit" did not clarify things.

Thanks!
eric_wa
14 years ago
Knox, not to step on Dans feet but your local hardware has them. Aluminum coupler with two set screws.

Eric
Dan _Staley (5b Sunset 2B AHS 7)
14 years ago
KG, I got at Home Depot, where I purchased the conduit. {{gwi:291227}} come in bags of 5 IIRC or singly. Last I checked EMT in Denver was US$1.65/10 ft and I think I paid ~3.49 for couplers, don't really remember tho. You see on the that the widest ~7ft use two 10 ft pcs. plus a small middle piece, requiring two connectors. I used 1 10 ft pc for two middle sections. Make sure whatever goes in the ground to hold the EMT goes in deeply. I used 3ft sections of 3/8 rebar or extra 28" sections of 1" SCH 40 PVC to secure with a shim to prevent sway and make vertical.

HTH.

Dan
web4deb
14 years ago
You could use black pipe instead of conduit.... It's fairly cheap and very strong. I use it for a lot of various projects.

Here is a link that might be useful: HFGH
dcarch7 d c f l a s h 7 @ y a h o o . c o m
14 years ago
Give these a try? Make your own connectors for very little money.

dcarch
{{gwi:291230}}

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