Being a good landlord requires transparency that entails sending you the bill so you can see for yourself what your portion is/will be. I'd ask the landlord to send you the bill or leave it at your door. I am not comfortable with the notion of just taking his word for it...I'd want to see the bill for myself.
And $320 seems awfully high! My electric bill for my home is approximately $70.00-80.00 per month and I am being conservative with the electronics here.
