A hole in the ground is a simple concept. Take a post hole digger, or shovel and start digging, however there is a right way and a wrong way to dig a hole. The wrong way is to dig a hole in the shape of an upside down cone. All the support is at the top of the hole. If the ground becomes wet, or freezes with a quick thaw, the post and concrete may become loose.
The correct method is to dig a hole straight down and then undercut the dirt to create a lip, or dig a pyramid shape. The main goal is to make the bottom of the hole flat, and wider at the bottom than the top. When forces push on the post, the wide base of the concrete supports the mast. The lip around the edge lifts up on the surrounding earth. The pyramid provides the same level of securing the concrete to the ground.
The size of the hole you dig is relative to the size of the mast you are installing. In general, a 1-5/8" O.D. mast should be set in a hole no less than 2 -1/2 feet deep below the frost line. The width of the hole can be as small as 8 inches, so long as the hole gets bigger at the bottom. The bottom of the hole should be at least 18 inches wide. This will support a mast extending up to 4 feet above grade. For taller mast, you will have increase the depth and width of the hole.
A mast for HughesNet or other Satellite Internet System using a 2-3/8" O.D. mast should be no less than 3 feet below frost line and 2 feet wide at the base. This will provide a stable base for a mast extending 5-7 feet above grade.
Before you set the mast in the hole, you need to prepare the mast so it does not twist in the concrete. There are several means you can use to install an anti-spin device. You can wield a piece of metal to the pipe, or clamp a muffler clamp to the mast. Some installers drill a hole and stick an old bolt into the pipe, leaving part of the bolt to extend into the concrete. Self-taping sheet metal screws are also sometimes used.
When working with a mast that is set in wet concrete, it is very easy to move the mast while adjusting the dish. The larger the anti-spin device the less chance the mast will move while the concrete is curing.
Our favorite method is to drill a hole through the mast, and slide a spike through the mast. If you plan to use the mast before the concrete is fully set, you should install several anti-spin devices. This will help secure the mast to the wet concrete as you work with the dish. If you use a 3/8 spike, drill the hole using a 3/8 drill bit , but stop drilling when the bit is almost through. Hammer the spike through the opening. This keeps the spike secured evenly in the mast. If the rod slips though the hole easily, use some tape to hold the rod in place as you set the mast into the hole.
A common method to set the concrete in the hole, is to pour in a little water, a little concrete, a little water, ect.. You will need to mix up the concrete with a long steel bar. The best method to mix concrete is in a wheel barrow, and then pour it in the hole. You have several options how you top the hole. You can leave the concrete a few inches below the frost line, or you can fill the hole and slope the top of concrete away from the mast.
You should never let the concrete form a slab over the ground. If the ground underneath freezes, it can push up on the concrete mass. When the ground thaws, the mast will be loose and no longer stable.
To prevent the cable from being damaged. You need to run conduit down the mast to a sweep 90. The coax should never come in direct contact with the concrete.
It is also a good idea to lift the mast a couple inches after you pour in the concrete. This prevent excess ground water from contacting the steel and causing rust. Even a galvanized pipe will rust on the cut ends. If you have excessive surface water, you should use the middle method to top the concrete. This prevents surface water from reaching the mast, and rusting at ground level.
Another method to keep the bottom of the pipe away from the earth is to place a brick, rock or piece of old concrete in the bottom of the hole. This keeps the post from touching the earth. It also allows you to use the pole before the concrete is completely set.
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