[FrodoOne]

In spite of the fact that it should be replaced, it can be repaired (at least, temporarily - to make it watertight) by using an appropriate "Epoxy Putty" - largely, on the inside.
(Here is just one example of such a product - Loctite All Purpose 2 oz. Epoxy Putty-1999131 - The Home Depot )

This product "mixes" like modeling clay.
Clean the "crack" and the inside of the box, mix the product, apply it to the "crack" and the inside of the box, squeeze the parts together, remove most of the excess on the outside and hold the parts in position with "Duct" tape (or similar.)
Smooth out the excess on the inside of the box - with a depth of about 1 to 2 mm for about 5 mm on either side of the "crack"
(This will act like a "plaster cast", a "damp finger" can do the "smoothing" - and you have only 5 minutes from mixing the product to complete the process)!

Retain the "excess" until it is "as hard as a rock" - at least 30 minutes - then, remove the "Duct" tape.

You should find that the box has been "repaired", if the product has adhered to the inside - as it should if the surfaces have been cleaned properly.

 

[FrodoOne]

Thank you for all the feedback!

"squeeze the parts together"

I think this will not work as the crack is most probably related to the shift of the underground conduit.

You wont know until you try it!
If the parts can be "squeezed together", epoxy putty within the crack and a significant layer of this acting as a "Plaster Cast" on the inside is likely to "hold" and make the "box" stronger than it was originally - since manufacturers tend to use the least amount of material that they can "get-away" with.

I have repaired the Die-cast box cover for an automobile windscreen wiper (and many plastic cases) using such a product and all have "lasted".

 

[FrodoOne]

See if I can post a picture here.

View attachment 674457 View attachment 674458 I put this box up each fall just to keep my outside water tap from becoming rusty then need replacement.
I have no shut off for it inside the basement.
So, was hoping to prolong the life of the tap through the winter months.
Seems to be working well going on 10 or so years now.

It is strange to imagine that an "outside water tap" might become "rusty", since (in my experience) all such (outside or inside) water taps are made of Brass!

 

[FrodoOne]

I agree totally. Look the only factor in this is that it can leak water into an already underground rated cable. Keep it simple and use this EPOXY. I have used this before and it is like hand-forming a ROCK. Two weeks ago I used it to attach a steel handle insert (sees very high temps) to a wood handle cover. Works like a champ and handles very high heat. All you care is that it locks out the water and re-forms the LB. Listen to instructions offered by FrodoOne, just do it and call 'er good!

I most sincerely thank you for your "support"!
Epoxy Resins (in many forms) are quite amazing products for effecting many repairs.
(This is partly because (as I posted at #14) "manufacturers tend to use the least amount of material that they can "get-away" with.")

 

[FrodoOne]

Remember that epoxy is vulnerable to UV light. Wait until it fully cures (give it a month) then scuff-sand it a tiny bit with a Scotchbrite pad, then prime it with an oil based primer (Rustoleum or Kilz Original)... then paint it.

While that is true of clear Epoxy Resin (often used with Fiber Glass reinforcement) in an exterior situation, it is hardly necessary with (non-transparent) Epoxy Putty, especially when used as a "Plaster Cast" on the inside of a "box".
Of course, any exposed "putty" needs to be painted to match any existing coating - as in this example. (Post #1)

For UV protection, I have found that two coats of a matching exterior acrylic paint to be quite satisfactory.