I would double the rate of pay for your highest worker. That should get you close.
Remember - auto mechanics are willing to post $100 per hour shop rates (and even higher in some cases). And you have to bring your car to them instead of the other way around.
Don't be shy, cover ALL of your expenses and charge what you are worth. In my state the average Journeyman takes about 8 years to get his license (even though it should only take 4, but that is another topic). Charge accordingly - you have a rare talent that is worth $$$$.
PS - I am not advocating that you rip people off, there is a moral component to this, but being an electrician (a licensed electrician) is a rare skill.
Rare = expensive. Charge accordingly.