Everything Active1 said is true. I would add the following:
You're going to need a lot of help from your wife. If your wife is not able to help, you're going to have to pay someone to help you. (And you can't afford to.) These things include: sending out invoices, bookkeeping, chasing slow payers, handling incoming phone calls, scheduling, running paychecks, talking to insurance agents, etc. Sure you could all this yourself, but you won't want to after a hard day of electrical work.
Also, before you hang the shingle, find yourself a mentor, preferably another EC owner who can (and is willing to) advise you. You are going to have tons of questions both with the business and electrical work you've never done before. Join networking groups to meet other business owners who can advice you on related but non-electrical topics like contracts, business insurance, health insurance property management, real estate, construction, vehicle maintenance, advertising, websites, signage, payroll, HR, etc.
As a union member, I was well paid when I worked and not paid at all when laid off. I averaged about three months of lay off a year. I got tired of being laid off unexpectedly and having to wait in line for a job so I decided to make my own job. Been almost three years now. Can't say I've had any regrets.