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Aerial Pole Tests                                        Also see 3” fence posts.....

Well, we finally got round to it, and tested most of the aerial poles on the market.

From the sublime...                                     To the ridiculous  (Pat showing what he thinks)

We set up a test rig on our back wall and just added weights on the end of the poles till

they failed. It was very interesting testing them all to destruction, in fact it was probably

the most fun you can have with your clothes on !

Generally, in terms of strength, the masts failed in the order one would expect, see table.

To help make sense of the results it is important to understand a few points :

1 Obviously as the pole gets longer it gets weaker !  As an example the 6ft x 1.25” x 16G

   pole failed at 25Kg but the 3ft length needed 62.5Kg to break it.

2 What counts is the free / unsupported length of the pole, i.e deducting the length covered   

   by the bracket. This can be significant. For the tests of the 3ft and 6ft poles the T & Ks

   were 11” apart, but when we put the 10ft poles on we widened them to 20” (to outsides).

  This is necessary to prevent putting too much strain on the brackets, or the brickwork....

  Thus the unsupported length on the 3ft poles was actually only 2ft 1”, on the 6fts it was

   5ft 1” and on the 10fts it was 8ft 4in.

3 It isn`t just about pole diameter, the gauge / thickness of the metal is just as important.    

   As an example a 6 foot x 1.25” x 18G pole failed at only 17.5Kg, but the thicker 16G     

   version didn`t collapse until 25Kg, and that`s a big difference.

As expected the 6ft x 1” x 18G (“Wickes Specials”) were the weakest, as we mention in

the article on Poles any installer who uses this mast must be called Bertie (as in bodger).

I was surprised that the 1” the steel poles weren`t actually that much stronger than the

1” alloy abominations.

The 1.25” x 18G pole is worth having over the 1”, but the 16G version is much stronger.

We did expect the 1.25” steel pole to be the strongest of the 6ft poles but we didn`t think that it`s superiority over the 1.25” x 16G alloy pole would be so small. Remember that the steel pole will start to weaken as it rusts.

The 10 foot x 1.5” pole lasted longer than I thought it would, but it certainly flexes a hell of

a lot which is why we only recommend them for aerial up to the size of a Yagi 18.

We don`t actually stock 1.5” poles at 6ft, or 2” x 14G at 10ft, but we do supply 5ft x 1.5”

and 8ft x 2.0” x 14G masts, we classify them as satellite poles. We included the tests

of this particular length of pole (at the 6ft and 10ft lengths) for the sake of comparison,

that and we`d probably be unable to break the shorter 5ft and 8 ft versions ones without bending the T & Ks, or pulling the brickwork apart......

The tests were primarily to establish pole strength, but we realised that they were also testing the 12” T & K brackets we sell, and the “Rawlplug type” wall anchors.

Both were very impressive. The T & Ks obviously flexed a bit under the type of the

loadings we were putting on them, but they didn`t bend that far, and never looked

anywhere near failing.

As for the wall anchors, I`ve got to say that unless your brick is soft or your hole is too big

(so you can`t get decent tightening torque on the screws) one has to wonder whether using “Rawlbolt” type fixings is worthwhile, particularly if one remembers the hole drilled in the

wall needs to be bigger. You only have to look at the pictures below to see we were putting on so much load that even the strongest poles were failing, yet the “Rawlplug” type wall anchors (and the brackets come to that) never showed up any deficiency whatsoever.

The Tale Of Destruction               

A 6ft x 1.25” x 16G pole tested to failure, great fun.....

It eventually collapsed at 25Kg loading, that`s 55lbs, on the end of a 6ft pole. That`s strong !

The Denouement   

There are 20 by the way, that includes cranked poles, plus we tested some twice if the results seemed abnormal.....

I must confess to some surprise that the cranked alloy poles weren`t actually any weaker than the straight versions, in fact the 3ft cranks were actually stronger than the three foot straights !  However it should be borne in mind that we could only test the cranked poles

in one direction. Testing them with a sideways "twisting" force would just have rotated the pole in its clamps. That said, I suppose one also has to bear in mind a bit of geometry,

the distance from the support, to the point at which the force is being exerted, is shorter

on a cranked pole.

The above comments don`t apply to the 9ft crank and the 6ft Supercrank poles.

The 9ft x 1.5” crank failed on the bend, and one assumes that was due to the fact it had a 6ft straight pole on the end of it, which is rather more than the 6ft versions have to cope

with ! Despite this it took 20 Kg to fail it. That`s behind a 6ft x 1.25” x 16G crank, though it was actually stronger than the 18G variant of that same pole. If using a 9ft crank with a

large antenna (e.g. an XB16) I`d chop a foot off it, or more, just to be on the safe side.

The 6ft x 1.5” Supercrank was comfortably stronger than even the 16G version of the 6ft crank. It was apparent that the cranked steel poles were weaker than the straight versions, but not being a metallurgist I wouldn`t know why.

The 3ft x 1.25” x 16G cranked pole was the strongest of all those under test. We were actually about to give up because it was getting dangerous trying to lift that much weight onto the test hook, particularly if it failed and fell on your foot ! Unlike the other poles, which kinked at the top bracket, this pole actually pulled the alloy apart, as in the picture (below right). Note the use of washers on the V bolt(s)......

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