You need to look out for the building permits to build fences. In some places, there will be power lines rooted and fencing, there might not be permissible. For example, if you live in Connecticut, you must take permission from the appropriate author

You need to look out for the building permits to build fences. In some places, there will be power lines rooted and fencing, there might not be permissible. For example, if you live in Connecticut, you must take permission from the appropriate authority to carry on the Connecticut fencing work.