[villagetinker]

Originally Posted by Laurel Maryland

Can you tell me if our lamp posts need to be cemented in? Are there pros/cons? Thank you.

I have no idea, the 3 or 4 that is have helped neighbors with were just buried about a foot to 1.5 feet in the ground. Be careful about how the under ground wire enters the post, 2 of the houses with problems were due to bad splices or rough edges on the post that cut into the cable. IMHO, IF you want to use concrete, I would use the mix in place technique. Once the new post has the underground cable PROPERLY installed, you simple pour a bag or 2 of concrete mix (dry) into the hole with the post in place, and water. The result is typically stronger than straight dirt, but not a strong as mixing the concrete and pouring it in the hole.
A word of caution, be very careful if SPLICES are needed and make sure these are UL approved underground waterproof splices or you will have future problems. I modified my reply based on a later comment, CONCRET IS NOT NECESSARY, compacted soil typically works very well.