A Question for the Budding Sherlock Holmes

Leprechauns. Oops, Scotland, not Ireland.

Illegal Leprechauns?

Leprechauns on holiday in Scotland prior to Scexit?

That is because the Greys have been lingering about on your property. They are the real cattle thieves. You need a new herdsman, and I know such a man, Rob Roy, by name, who will herd your cattle down from the highlands, and feed them in the lowlands, and be back in Scotland afor ye.

In lieu of Rob Roy, get a Kimber. If you catch a Grey with his three-fingered slimy cold hand on one of your fence finials, then you have your answer.

Oval? That's definitely an egg shape. I think someone wants to eat the egg and then when they realize it's not an egg they drop it.

Look for broken teeth on the ground.

Birds with teeth? Like Pterodactyls?

Issue: In uncertain something is happening at an uncertain time.

Solution: Motion activated camera will capture and record an image of a certain something and certainly record the time.

What say you, Doctor Watson?

Elementary, Sherlock, elementary!

look up the phrase, "cold enough to freeze the balls off a brass monkey"

you'll have your answer

If the post and the steel tops are not tapered, I doubt differential thermal contraction is the issue.

I know that you said "wedge", but.................

Just for fun, throw one of the steel tops in the freezer overnight and then heat the post top with a torch, just before you reassemble them. Then sit back and watch.

So the solution is to drill a small (3mm or so) weep hole in the bottom of the fence post tube, so the water can drain off.

I have seen similar effects on large crimped-on cable terminals used on electrical station circuit breakers, etc. The cable sweeping down from the bus above to the breaker's bushings is a nice path for the water to run down, which then collects in the natural "cup" of the terminal which has been compressed on the cable's end. If a weep hole is not provided by the terminal manufacturer or drilled in the field by the installer, the resulting ice during winter weather expands and splits the terminal. Notice the bulge and crack down near the pad of the terminal in the photos - a lot of force there!

Believe it or not but that little hole in a lug is for ensuring a visual inspection that the conductor is seen to be fully inserted into the lug. And any lug connection should face with the barrel pointing downwards to prevent any water ingress along the exposed conductor, into the lug. If the compression of the lug/palm connector is done properly, i.e hex crimp as shown, the conductor is squeezed sufficiently to become almost solid with near to no air pockets.

But as ali is not a solid, but flows from any compression points, the palm connector/lug still needs to be installed barrel facing down and the curve on the conductor allows water to flow away from the barrel. We call it a goose neck. Alternately I would have used this;

And looking at the photo, I would suggest the palm connector was wrongly crimped at installation stage and the fracture was made at crimping stage. It must have had a nice corona.

I was aware that at least some lugs have a hole for inspection purposes, but for an installation where water can run down the conductor and into the barrel of the lug, the hole also serves to allow it to drain.

It is often not possible to build a high voltage installation such that the barrel points downward - Usually the bus height is above the elevation of the breaker bushings, for example.

You may think that proper compression of the lug would eliminate all the voids, but if you cut cross-sections of the compressed fitting, you would find all sorts of little crevices through which the water can seep. And water, being the small molecule it is, WILL find its way through them. You cannot crimp the connection enough to eliminate all the voids.

These crimps were done properly, and the connectors were fine when installed two years before the photo. The bulging and cracking was from water that had entered the barrel and frozen, but since the installer had not drilled weep holes (since the Mfr didn't provide them), the ice did its thing. Other lugs with weep holes in different parts of the same switchyard didn't have this problem.

Never built a sub or yard where I have lug barrels facing upwards. Not even in the US. Bad design practice allows for upward facing lugs, hence the drawing for the correct connector method.

The hole was originally for soldering, (or if in the US, 'soddering'). The lug was soldered, (wiped), and the hole allowed the installer to enure the lug barrel was filled with conductor and wiping metal. The barrel, when filled, the wiping metal flows out of the hole, ensuring a filled void.

Hence, a water block and sealed lug, just like that!

Additional info

http://www.sanchem.com/electrical-contact-lubricant.html

If you have an upward facing barrel, make sure the barrel is flooded with something similar to the above and just space the crimps out by 5mm, i.e hex crimp +5mm, hex crimp+5mm and the if there is any moisture in the barrel after that, it will not freeze and damage the barrel. The excess grease is wiped off as it squeezes out the barrel.

Crimp steps as such above.

NB: this is bimetalic ferrules but see the ring steps between crimps.

Because no-one has glued them on?

(usual disclaimer)

Two dissimilar metals with different coefficients of expansion/contraction and an increase in air pressure in the tube, results in a popped off finial. A small breather hole in the post should allow the finial to stay in place.

That looks like ~11% expansion, all right!

Mayhaps Mrs. Watson was observing her trials for further testing. 'The Finial Murders of Sauchiehall St'.

I believe you have exposed an even greater mystery, how did that pole get filled with water?

I really would never have expected that. Can you lift a large limestone block enough to get a chain under it this way? Could ice be used to drive wedges into the seam where blocks are to be cleaved from the formation?

Ever seen what a freeze-thaw cycle does to masonry (roads, walks etc.)?

We tend to use pre-formed concrete items for dog and bird watering device by one of our trees. During a recent cold weather snap from the arctic (but here in Lubbock Texas), the temperature reached about 4-6 °F (on the ground), and that is -15.6 to -14.4 °C.

The first container developed a crack and no longer holds water. I tried to seal the outside of this one with Flex-Seal (did not work at all for me, and would not stick to the concrete). I bought another one (bird bath bowl) from a stone and rock landscape place, and it also leaks, due to a crack already present (could not see due to dirt in it at time of purchase). I used Rockite (gypsum Portland cement) inside the basin of this one about 1/8" thick, let's see how long it lasts, but so far it holds water quite well. Gypsum Portland cement seems to cure stronger with long term water exposure, but I wonder about differential thermal expansion of the two separate types of concrete present.

Who fills it with water?

One's reach should always exceed one's grasp.

Clearly this finial is well on its way to greater things

Like the yard.

I find steel and aluminium together, will corrode, possibly pushing the tops out!

I would never ever put the two together, without something to prevent corrosion.

May I suggest cleaning one tube and one top and smearing the contact area with grease. This will not prevent corrosion completely, but it should slow it down dramatically!

If this is true and this one comes out "far" slower, you know that this is the problem.... But how to fix it is another problem!!!

Possibly turning down the tops and putting a plastic sleeve over where it has tube contact, it to take up the difference to the tube comes to mind.....guessing only!!

Aberdeen, this time of year. I'm freezing my ***** off down here on the SE coast. Maybe your fence has had a similar experience ?

You have lost your stars? I have to be honest, I never gave icing up a consideration. Now who would have thought that? The obvious, if we had known the facts. Good one.

If I walk to the local pub, I have a hangover next morning. WALKING IS DANGEROUS, AVOID IT !

Place small set screw to hold cap on post

Were has been manufactured the top ? Could the behavior not be a consequence of the Brexit ?

Not Brexit at all, it was in reaction to Prime Minister May passing by, she is a hottie!