Every finished basement reno we quote reaches the same fork in the road. The general contractor has a circuit list — pot lights, two TV walls, a bar, a bathroom, a laundry, an office, a gym, sometimes a sauna. The first instinct is to run each one back to the main panel upstairs. The better answer, on most basements bigger than a single rec room, is a 60-amp sub-panel down in the mechanical room with the branch circuits originating right where they land. Here is how we think about the decision, what the install looks like, and where the money is actually best spent.
When the sub-panel wins over individual circuits
A 15A general-purpose receptacle circuit and one lighting circuit for a small basement bedroom can absolutely run back to the main panel. The math turns the other direction quickly:
- Six or more new branch circuits. Once the circuit count gets past five, the labour of fishing six cables back to an upstairs panel exceeds the labour of pulling one feeder and landing the branches local. Every additional circuit after that widens the gap.
- The main panel is more than 50% loaded. A second 200A panel-board worth of spaces in the basement is not the answer — but a 60A or 100A sub-panel takes one or two spaces upstairs and gives you twelve to twenty new slots in the basement. Cleaner load distribution and an easier inspection.
- The basement has a bathroom, a wet bar, or laundry. Each of those requires dedicated GFCI or Dual-Function circuits. Concentrating them at a local panel means short runs to the GFCI loads where the protection actually has to be.
- Future-proofing for a secondary suite. Many Hamilton, Burlington, and Stoney Creek finished basements eventually become legal secondary suites. A 60A sub-panel sized and located with that in mind is a fraction of the future scope.
If you are doing less than that (a single bedroom and a closet light) individual circuits to the main panel are fine and we will say so up front.
Sixty amps versus one hundred amps
For most finished basements the choice is 60A or 100A. The honest breakdown:
- 60A feeder handles general-purpose lighting and receptacles, a basement bathroom, a small kitchenette, a wet bar, an office, a gym with treadmill and TV, and a 20A laundry. Real continuous load is rarely above 25 to 30 amps. Common conductor: #6 AWG copper, or #4 AWG aluminum if the run is long.
- 100A feeder is what we run when the basement is genuinely going to be a self-contained suite — full kitchen with electric range, full laundry, dedicated HVAC, EV charger in the attached garage shared off the basement panel. Common conductor: #3 AWG copper or #1 AWG aluminum.
For a typical rec-room-plus-bathroom-plus-office basement, 60A is the right pick and leaves headroom. We very rarely undersize at 60A; we sometimes oversize to 100A when the customer is on the fence about a future suite and the feeder cost delta is small compared to redoing it later.
Where the sub-panel goes, and the working clearance rule
This is the part the framing plan usually gets wrong. The OESC requires working clearance in front of the panel: one metre clear depth, the full width of the panel plus a margin, and 2 metres of headroom. That space cannot be blocked by drywall, by a furnace, by a shelving unit, or by a door that swings into it. Inspectors check this every time.
The good locations:
- The mechanical room, on the wall adjacent to the existing main panel or the wall behind it. Short feeder, all the noisy electrical equipment kept in one space.
- A utility wall in the laundry or storage area if the mechanical room is too tight. Keep the front of the panel clear and label the space on the floor plan as "no shelving."
The bad locations we get asked about and decline:
- Inside a finished closet with a hinged door. The door blocks working clearance when it is open.
- Behind a piece of finished cabinetry "with a removable panel." Inspectors do not love removable-panel arguments and the next homeowner will not know about it.
- In a bathroom or near the laundry sink. Not allowed and not a good idea.
The feeder run, kept short and accessible
For most installs the main panel is one floor up, often on the opposite side of the same wall as where the sub-panel goes. Best case the feeder is two metres of conductor through one wall penetration. Real-world cases:
- Short adjacent run. #6 AWG NMD90 for 60A or #3 AWG for 100A through the floor plate, into a knockout at the main panel, terminated on a 2-pole breaker matched to the feeder size. Half an hour of work plus the panel landing.
- Longer interior run. Up through a wall cavity, along a ceiling joist bay, down into the sub-panel location. Stapled per the OESC, supported every 1.5 metres, fire-stopped at penetrations. Two to four hours depending on access.
- Run through a finished ceiling. Hardest case. Either fish it or open a chase. If the basement ceiling is already drywalled, the chase usually wins.
Conduit is not required inside the building envelope for NMD90, but we use EMT or PVC at any point the cable comes out of a stud bay and sits exposed in the mechanical room. Clean install, easier to add to later.
Slot count and the breaker mix you actually need
Twelve-space sub-panels are the smallest we install for a finished basement. More commonly we land a 20- or 24-space cabinet, mostly empty on day one. The reasoning is in the breaker math.
For a typical Hamilton finished basement with one bedroom, one bathroom, an office, a rec room, and a wet bar, the breaker list lands around:
- Two general-purpose AFCI 15A or 20A circuits for the bedroom and the office. Both required AFCI under the current OESC.
- One Dual-Function 20A circuit for the bathroom receptacle, GFCI + AFCI combined per the recent code revision.
- One Dual-Function 20A circuit for the wet-bar receptacle within reach of the sink.
- One AFCI 15A circuit for the rec-room lighting and receptacles, depending on layout.
- One 15A circuit for the bathroom exhaust fan and lighting (some installs combine, some separate).
- One dedicated 20A circuit for the bar fridge.
- One 30A or 40A 240V circuit if a sauna, future heat pump, or EV charger is in the future plan.
- One 20A circuit for the laundry receptacle if the basement includes laundry.
That is eight to ten breakers minimum, and the AFCI and DF breakers are wider than standard breakers in most product lines. So a "12-space" cabinet is realistically full at eight or nine landings. The 20- or 24-space is the right buy. The slot cost is marginal at install and saves a panel swap when the customer adds a sauna in three years.
Bonding and the four-wire feeder
The sub-panel feeder is four conductors: two hots, one neutral, one bonding conductor. Inside the sub-panel cabinet the neutral bus is isolated from the cabinet, floating, and the bonding conductor lands on the cabinet ground bus, which is bonded to the cabinet. The neutral and the ground are not bonded together at the sub-panel. They are bonded once, at the main service panel upstairs.
This catches owners and the occasional handyman every time. A neutral-to-ground bond at a sub-panel creates a parallel path for neutral current to flow through the bonding conductor and the cabinet. The inspector will fail it on sight, and we have seen this enough times in DIY-built basement panels that we mention it in every estimate. No ground rod is required at an interior sub-panel inside the same building. That is a detached-structure rule, not an interior one, and the same principle that applies to a detached garage sub-panel does not apply here.
Where the money actually goes
Deciding what to fund first on the basement electrical:
- Pay for the sub-panel. Landing a clean feeder and a properly-sized cabinet is the foundation everything else sits on. Cheaping out here is the decision that ages worst.
- Pay for slot count. A 24-space cabinet costs maybe $80 more than a 12-space and lets you add five future loads without touching the feeder.
- Pay for the correct breaker types day one. Swapping a standard breaker out for an AFCI later costs about double what landing it correctly the first time costs.
- Pay for one dedicated 240V slot for whatever the future load will be: sauna, EV, heat pump. Even if you do not run the circuit, having the breaker pre-thought and the conduit stub roughed in is half the future cost.
What the ESA permit covers
The permit covers the feeder, the sub-panel, the bonding, and every branch circuit landed at install. We pull it in our name and the inspector signs off after the basement is energized. We typically schedule the rough-in inspection before drywall and the final after the trim devices are in. Background on what the inspector actually looks at is in our ESA permit post.
When to call us
If you are planning a finished basement across Hamilton, Burlington, Waterdown, Ancaster, Dundas, Stoney Creek, Oakville, or our Muskoka service area, and you have a circuit list longer than four or five items, we will quote the sub-panel option against the individual-circuits option honestly. Sub-panel and feeder work is most of what we do day to day. Send us a photo of your main panel and a sketch of the basement floor plan with intended loads. Request a quote.