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How strong are different sizes of steel electrical conduit?

Posted by knoxvillegardener 7a (My Page) on
Sun, Feb 21, 10 at 22:09


I would like to build trellises from steel electrical conduit for vine-type garden vegetables (e.g. squashes, melons).

Can someone give me some guidelines on the load-bearing capacity of different sizes of steel electrical conduit?

For example, if I have a six foot span of conduit, how much weight could I expect it to comfortably support and how does this weight change with the diameter of the conduit?

Are there some tables online where I can look up these values? (I tried a Google search but wasn't able to find anything.)

Although some of the plants I'd like to grow are fairly lightweight (e.g. green beans) so load-bearing capacity won't likely be an issue, some others (e.g. watermelons) can produce fruits that weigh 30 pounds apiece. With the possibility of having a number of fruits at once being supported by a single trellis, this could be an issue.

My goal is to figure out the right size of conduit to use - something that's definitely strong enough (e.g. including a margin of error) - but not unnecessarily large as the cost to buy conduit and fittings rises with diameter.

Any useful guidance you could give me on this would be much appreciated.

Follow-Up Postings:

RE: How strong are different sizes of steel electrical conduit?

Sorry, I never did a stress test on conduit, but I have used it for many different projects. The 10' pieces are really cheap, but it is the fittings that are costly. If it were me then I would just buy a 10' piece of something like 1" and see if it will hold what you think will be the weight of the stuff you plan to plant on it. If you can tie, bolt, screw or weld the conduit you could save a lot in cost. Unless you plan to hang a cow on it at some time I can't see how you would need anything much bigger. I am sure 2" would hold twice as much, but that would be overkill.

RE: How strong are different sizes of steel electrical conduit?

  • Posted by jolj 7b/8a-S.C.,USA (My Page) on
    Mon, Aug 13, 12 at 15:38

All metal tubing(conduit/pipe) is stronger vertically then Horizontally. Their should be 1 foot in the ground for every 3-4 feet that is out of the ground to a height of 10 feet.

RE: How strong are different sizes of steel electrical conduit?

I'll look in my Engineer's Desktop Reference to see if there is any data on strength of pipe structures mounted horizontally.

Try not to lock yourself into buying it (as in, laying out your hard-earned money for it) but rather see what you can find at salvage yards or various "throw-out" places.

Rule of thumb:::::

Rigid electrical conduit is approximately equal in strength to ordinary schedule #40 black water pipe. The most salient feature of elec. conduit is the hot-dip galvanizing. It will not rust or corrode in the outdoor weather.

For a six-foot span you could get 2" pipe for very little cost and it will be incredibly strong. It will hold just about anything you put on it. If it is rusty when you get it then sand it down lightly and coat it with Rustoleum "Rustformer". It creates a polymerizing finish on tight rust and becomes the primer coating for a top coat. Medium green is good.

I apply "Moore's Law" to structures like this.

Moore's Law:::::::::::::::

If a little is good, then more is better and WAY, WAY TOO MUCH IS JUST RIGHT!!!!! LOL

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