Can I sub-contract electrical work?

Can a licensed contractor sub-contract electrical work?

Yes, but only to another ECRA/ESA-Licensed Electrical Contractor.

If I contract out electrical work, can I say my company does electrical work in our advertisements?

No, only Licensed Electrical Contractors can advertise that they do electrical work. If your company is a general contractor, your ads must say that you only use ECRA/ESA-Licensed Electrical Contractors to perform any electrical work.