Choosing a Mast Material
- 1-1/2″ EMT (Electrical Metal Tubing, O.D., 1.740″, 0.065″ wall)
- 1.9″ O.D. Fence Rail
My short story: A few years ago, like many of you, my aim was to put up the best mast I could for the least cost. I chose EMT because it was as heavy or heavier gauge (16 gauge) than the common telescopic (mostly 18 gauge) and I found sources for the DOM steel to make the Couplers to join the 5’ mast pieces. At 50’ high with a hex on top and with a strong guy system, it served me well for 5 years. When using EMT at 50’, I used the 4 guy system plus a 5th guy only on the top level pulling in the safest direction just in case. (I don’t mention EMT at that level with the availability of the 1.9 fence rail.)
During my EMT years I was looking at a heavier mast material, 1.9” O.D. Fence Rail, but couldn’t find DOM steel to match. Finally, I located a manufacturer to supply it. 1.9 is stronger, has a higher yield point, is galvanized and comes in several wall thicknesses. I chose the 13 gauge, 0.090+” size. The downside is the cost-about twice the price of the 1-1/2” EMT. This combination with just Couplers was used successfully for a year or so then…
In my older age I got a little more conservative by looking for more “insurance” for a safer mast. I figured the less EMT or 1.9” that is exposed the sturdier the mast will be. So I added 5” long Reinforcers and placed them at the midpoint of all the 5 footers that are above the top standoff bracket. So now, between Couplers/Reinforcers and a good guy system, I’m pretty confident about my mast.
So the problem facing us is choosing the best option to safely satisfy your antenna needs at a reasonable cost. My personal choices for various situations are below.
|to 20′||EMT||Couplers only; up to hex-beam antenna|
|20-30′||EMT||Couplers + Reinforcers above top standoff;|
antenna <5 sf wind load; 4 guy system
|30-40′||EMT||Couplers + Reinforcers; Light antenna load, |
ie: tv types; 4 guy system
|to 20′||1.9||Couplers only; hex-beam type antenna load|
|20-30′||1.9||Couplers + Reinforcers; hex-beam type antenna|
|30-40′||1.9||Couplers + Reinforcers; hex-beam type 4 guy system|
In every case you definitely need a guy system according to accepted standards, ie., generally guys every 10’ of unsupported mast starting with mandatory guys at the top of the mast. If not mentioned above, a 3 guy system is adequate. Also, when mentioned, Reinforcers are only needed above top standoff. Also, hex antenna has about 5 sq ft of wind loading.
Above info is not that from an authority on the subject – just an opinion and general guide. Your feeling safe and confident about your install is an absolute must.