Question about pole-mounted transformers

[cmoschip]

Hello all. I am not a lineman, nor do I work in the electrical generation or transmission industry. I have a quick question about best practices for the mounting of transformers on wooden poles and I need the opinion of professionals such as your selves.

At our place of business we expanded a machine shop approximately 18 months ago. An additional power entrance to the building was constructed by our sub contractor that consisted of several poles and 3 pole-mounted transformers. Being an extension of service on our property this additional entrance and its equipment is owned by us and not the electrical infrastructure provider.

Yesterday we arrived to find that we had lost 1 leg of 3 phase power over the weekend. We called the sub contractor that installed these facilities and they found the issue was that the entire assembly of 3 transformers and their mounting bracket (friction bracket) had slid down 10-14 inches and pulled one of the transformer's feeds from the primary electrode (see pictures).

My question is about best practices. Being unable to assure the exact diameter of the wooden pole, I find it odd that a lynch pin of sort was not used to assure zero movement of the transformers and their bracket. Is my installation "normal" or should there be some method to positively keep the entire assembly from movement due to gravity?

Thanks for reading - I do appreciate it.

Robert