Adding a bedroom over the garage in Towson, finishing a Catonsville basement, or building a sunroom off a Parkville rancher means new circuits, and usually a hard look at whether your existing panel can carry them. David Williams Electric has wired additions across Baltimore County for more than 30 years (Maryland license #11734), and we tell you the real cost and the real load math up front, before a single wire gets pulled. If the panel can’t take it, we say so on day one instead of after the drywall is hung.
What an addition actually asks of your panel
A lot of Baltimore County homes were never built with a second wing in mind. The brick Cape Cods around Parkville and Essex, the 1950s ramblers in Catonsville, and plenty of Towson colonials still run on a 100-amp service, and some of the older Pikesville and Reisterstown houses are smaller than that. Bolt a 600-square-foot addition onto one of those, with its own lights, receptacles, baseboard or mini-split heat, maybe a bathroom, and you can quietly push the whole house past what the service is rated for.
That is why every addition we wire starts with a panel load calculation, not a guess. We add up the existing connected load, the new addition’s demand, and the National Electrical Code’s required margins, then tell you one of three things: your panel has room, your panel needs a few slots freed up, or your service needs to grow (commonly 100 amps to 200). You get that answer before the framing inspection, when changing course is still cheap.
New circuits done to current code, not 1962 code
The room may be new, but it ties into wiring that may be decades old. We run dedicated circuits sized for the actual loads going in: 20-amp small-appliance circuits if the addition includes a kitchenette or wet bar, AFCI protection on the bedroom and living-space circuits the code now requires, and GFCI wherever water is in the picture. Outlet and switch spacing, the arc-fault and tamper-resistant requirements, smoke and CO placement for the new bedroom: all of it gets built to the code edition Baltimore County is enforcing today.
If the existing house has mid-century aluminum branch wiring (we still find it in 1960s-era additions and panels around the county), we do not just splice copper to it and hope. We correct those connections properly by pig-tailing with copper using listed ALUMACONN connectors, so the new work and the old work meet at a junction that won’t loosen and heat up behind your new wall.
Permits and inspections, handled for you
Addition wiring in Baltimore County needs an electrical permit, and the work gets inspected by the county’s Department of Permits, Approvals and Inspections. We pull the permit under our Maryland master license (#11734), schedule the rough-in inspection so it lands after the wiring is run but before the insulation and drywall go up, and then schedule the final once devices and fixtures are in.
Getting the rough-in timing right matters more than people expect. Miss it, and an inspector can make you open a wall that was already closed. We coordinate with your general contractor or your other trades so the electrical sign-off doesn’t become the thing holding up your drywall crew.
A straight number before we start
Surprise change-orders are the part of a remodel everyone dreads. We quote addition wiring with up-front pricing: the circuits, the panel work if it’s needed, the permit, and the inspections, in writing, before the job begins. If the load calc says you need a service upgrade, that’s in the quote on day one, not sprung on you at rough-in.
And the work is backed by our 100% satisfaction guarantee. If something about the finished wiring isn’t right, we come back and make it right. Whether the addition is in Owings Mills, Essex, or somewhere in between, you deal with the same licensed electrician from the first walkthrough to the final inspection.
Frequently Asked Questions
Will my existing panel handle a new addition, or do I need a service upgrade?
That depends on your current service size and what the addition adds. Many older Baltimore County homes run on 100-amp service, which a sizable addition (extra HVAC, a bathroom, a kitchenette) can push over the limit. We run a panel load calculation first and give you a clear yes, no, or upgrade-to-200-amp answer before any wiring starts, so it's never a surprise at inspection.
Do I need a permit to wire a home addition in Baltimore County?
Yes. Addition wiring requires an electrical permit, and the work is inspected by Baltimore County's Department of Permits, Approvals and Inspections. We pull the permit under our Maryland master license (#11734) and handle both the rough-in and final inspections so you don't have to navigate the county process yourself.
When does the rough-in inspection have to happen?
The rough-in inspection has to pass after all the wiring is run but before insulation and drywall close the walls. We schedule it to fit your construction timeline and coordinate with your contractor, because if that inspection gets missed you can end up reopening a finished wall. Getting the timing right is one of the main reasons to bring in a licensed electrician rather than handling addition wiring informally.
My older house has aluminum wiring. Can you still tie a new addition into it safely?
Yes. Where an addition meets existing aluminum branch wiring (common in some 1960s-era Baltimore County homes), we correct the connections by pig-tailing copper to the aluminum with listed ALUMACONN connectors rather than splicing dissimilar metals directly. That gives the new work a safe, stable connection to the older wiring.
How much does home addition wiring cost?
It varies with the size of the addition, the number of circuits, and whether your panel or service needs upgrading. Rather than a vague estimate, we give you up-front pricing in writing before the job starts: circuits, any panel work, the permit, and inspections all spelled out. The work is also backed by our 100% satisfaction guarantee.
Serving Baltimore County
David Williams Electric provides home addition wiring throughout Baltimore County, including Towson, Catonsville, Owings Mills, Pikesville, Parkville, Essex, Reisterstown. Explore all Baltimore County electrical services or learn more about home addition wiring across Maryland. Call (410) 781-4357 for a free, up-front quote.
