I've hired a licensed electrician to upgrade the entrance cable from the service drop. However, I'm trying to expose the work area for him and am having trouble finding it behind the sheet rock and insulation. I know I must be in the neighborhood because I found the phone and satellite cables, which enter nearby. There are 3 studs placed together in the general area. I'm wondering if it's possible that the middle stud has been ripped and that the cable is behind it. Does anyone have experience with this?

Lets start by determining why you want to change out the cable.

Then I would ask you to contact the Power Company and see what size & the number of conductors they used for your area.

You have to have that information anyway since it is their equipment you are messing around with.

In our area, the power company use a 3 wire #4/0 AL cable, installed as a lateral (underground) even though the homes were only going to be wired for 60 amp at the time they were constructed.

#4/0 AL wire is listed as 200 Amp service feeder cable. They anticipated the future needs of the homes and planned ahead so that they would not have to dig the cables up every time the service was upgraded.

If you have a service drop, they may well have done the same, call them.

As to your specific question, the service feeders will generally enter the home near where the electric meter is.

While rewiring for a new range (50 amp), the electrician found a potential hazard. Our service drop (not underground, though I wish) is 100, as is the breaker on the outside box. The entrance cable is only 50 (maybe 60?)!

Before you go ahead with the work, please call the Power Company and verify the size of the cable and the load they carry to your home.

How old is this home? Is it a mobile home?

Service Feeders for 100 amp service are #4 copper or #2 Aluminum (per table 310.15 (B) (6).

What size cable do you have now?

Also 100 amp is still the minimum size service you can use in a residence. That is fine for most of the smaller homes.

The only real way to determine whether you need to increase your electrical service is to have a licensed electrician do a load calculation for your home.