Adding a mast to a house
If you are extending your service entrance and need to use splices, you would also need to use an appropriately sized junction box so the splices are accessible. Without that, you cannot splice them. If it is, indeed, your service entrance, you might be well served to get the assistance of a qualified electrician; it's a place where you do not want to have any occasion to say "oops! I shouldda done that better."