Monitoring Power on Twin 110v lines
To measure single-phase power, simply measuring voltage and current does not yield actual power with any precision. Any power factor issues will skew the results, often badly.

Consider instead a solution like this one from SiLabs with their Si8902, which uses digital-side isolation, not line-side. Or here is another approach from Linear Tech using their LM2940, where isolation is at line side. Similar isolated solutions exist from Texas Instruments, and many other companies.

If you must measure in discrete parts,


Measuring current on both live and neutral legs is often useful - a difference would indicate an earth leak inside the domestic network. Inductive clamps are safe enough.
Measure voltage across live to neutral using either an isolated voltmeter or an isolating voltage sense IC
Measure phase on both voltage and current sense channels, so you can have a PFC correct power figure such as the utility company bills you for.


An important point to keep in mind:
Most utility companies frown upon any equipment connected on the distribution side of your domestic entry point / fuse box - all devices including power monitoring must be on your side of the fence. Also, connecting anything at all beyond the fuse box may violate UL or equivalent certification for your geography, leaving your home exposed to diminished insurance coverage.