As we look forward, we see uncertainty in the macroeconomic environment, which could result in softer demand in our commercial and industrial and mechanical businesses. Additionally, we expect to see a negative impact on our sales and operating profit from foreign currency translation in the third quarter. Our HVAC business has substantially anniversaried the R22 conversion, and should benefit from better year-over-year comparisons as well and as well from the warmer weather.
With that, I will turn it over to Chuck Hinrichs.
Thank you, Mark. Good morning, everyone. As Mark stated, our second quarter results exceeded expectations. Net sales increased 26.7% over the prior year, reflecting the inclusion of sales from the acquired businesses. Sales in the quarter reflected continued growth in our North American commercial and industrial motor and mechanical businesses and Unico. This growth helped offset weaker sales in our HVAC, Asia, and European businesses. Also, sales were negatively impacted by foreign exchange rates, which reduced sales by 2.1% in the second quarter.
Our second quarter results included $0.5 million or $0.01 per share in restructuring charges related to plant closures to generate the EPC synergy savings. We will talk more about these activities later. In comparing our second quarter results against the prior year results, please recall that in the second quarter of 2011, we took a $28 million charge for a warranty expense item.
In summary, our second quarter 2012 earnings per share of $1.49, or adjusted earnings per share of $1.50 per share, were above our guidance for the quarter driven by a stronger than anticipated performance from our HVAC and C&I businesses.
This chart shows the growth of second quarter 2012 net sales, adjusted operating profit and adjusted diluted earnings per share as compared to the prior year. The takeaway here is that we generated growth in all key operating metrics as we benefited from the acquired businesses and grew our mid and late cycle businesses, offsetting the weak market demand in our HVAC, Asian and European operations.