My 1 year Non-O Business Visa is set to expire Sept 7, 2015. I have a trip planned to Canada (where I got my current Non-O) August 2-28, 2015. Can I get a new Non-O Business Visa before the current one is set to expire?

Possibly you mean non-immigrant B ? Or a non-immigrant O ?

The requirements to obtain an extension of stay in Thailand are different for each case.

My 1 year Non-O Business Visa is set to expire Sept 7, 2015. I have a trip planned to Canada (where I got my current Non-O) August 2-28, 2015. Can I get a new Non-O Business Visa before the current one is set to expire?

Whether your multiple-entry non-immigrant visa be of the category O or B, you can without a problem apply for a new visa before the "enter before" date of the old visa.

I have a Non Immigrant "O" and I have renewed it, in my own country Ireland a few times now, over the years, before the old/current/existing visa expired.

and had no issues what so ever in doing so.

Yes I meant Non-B unlimited entry, and my 'Enter Before' (not expiry) date is Sept 7, 2015. Thank you for the replies!

Edited November 12, 201411 yr by mal129