A typical Muskoka cottage was wired once - sometimes in 1965, sometimes in 1985, occasionally last decade - and the panel that went in then is the panel that's there now. By the time the bunkie is built, the garage has lights, the boathouse has a fridge, and the sauna is on the wish list, the main panel is full and the long extension cord is starting to look like a permanent fixture. The right answer is a sub-panel at the remote structure. The detail is different for a bunkie versus a boathouse versus a sauna shed, and getting it wrong costs the back half of the job. Here is what each scenario actually looks like.
The "is the main panel actually full" check
Before we quote a sub-panel we look at the existing main panel. Sometimes "full" is real - every space populated, no doubles available - and sometimes "full" is two single-pole breakers that could be combined onto a tandem and free up two slots. The first conversation is:
- Bus capacity. A 100A panel is rated for 100A of demand, not for whatever the breakers sum to. We do a load calc against the existing installed loads with code demand factors and see where the cottage really sits.
- Available spaces. Sometimes adding a tandem or two clears the slot problem.
- The brand and age of the panel. If the main panel is a 1970s FPE Stab-Lok or a Federal Pioneer, the right job is replacing the main panel and feeding the sub-panel from a clean 200A service. Detail in our Stab-Lok post.
If the bus is fine and we just need a feeder out to a remote structure, the sub-panel install is straightforward. If the cottage is on a 60A service and you're adding a bunkie, a hot tub, and the boathouse upgrade in the same season, the conversation is a service upgrade and a sub-panel.
Scenario one - the bunkie
A bunkie at a Muskoka cottage is typically 20 to 50 metres from the main cottage, frame construction, sleeps two to four. The electrical needs are modest - a couple of lighting circuits, a few receptacles, maybe a small heater for shoulder-season use.
- Feeder size: 60A is almost always plenty. Real continuous load is 10-20A even with a small heater running.
- Run method: Trenched PVC with RW90 pulled through is the standard. Trench at 600 mm, sand bed, warning tape, sand cover, topsoil.
- Sub-panel: 60A 12-space sub-panel mounted on plywood backing inside the bunkie. Siemens, Eaton, or Schneider.
- Grounding: Ground rod at the bunkie, bonded to the sub-panel ground bus.
- Branch work: AFCI for the bedroom circuits per OESC, GFCI on any kitchenette or bathroom receptacles.
The bunkie is the easiest of the four scenarios because the loads are small and the structure is dry. One day for the trench and cable, half a day for the panel and branch work.
Scenario two - the detached garage
The cottage garage is rarely just a garage. It's a workshop, a boat storage building, sometimes a future bunkhouse. The loads scale accordingly.
- Feeder size: 60A for a basic workshop, 100A if there's a welder, a Level 2 EV charger planned, or a serious workshop heater. The 100A feeder is what we install most of the time at cottages because the owner usually wants the option to expand without re-trenching.
- Run method: PVC and RW90 if the soil is workable. TECK90 direct-buried if the run hits rock - and on the Canadian Shield, the run often hits rock within the first two metres. TECK saves you the buried-conduit fight.
- Disconnect at the structure: The sub-panel main breaker satisfies the disconnect requirement on its own.
- Heating load: An electric workshop heater is its own dedicated 240V branch in the sub-panel. We covered the sizing for the heater itself in our electric garage heater post.
- Future EV: If a charger is planned, size the feeder for it now even if the charger goes in next year. Trenching twice is the most expensive way to do this.
Scenario three - the boathouse
The boathouse is the hostile environment of the four. Wave-driven spray, freeze-thaw, six months unoccupied. The electrical detail tightens up.
- Feeder size: 60A is normal. 100A if the boathouse has a second-storey living space, a boat lift, or extensive dock circuits.
- Run method: The big question is whether any part of the run is over or near the water. TECK90 direct-buried under the ground portion, then transition to indoor wiring at the boathouse wall. If the cable has to cross a deck or dock to get to the boathouse, we mount in conduit above water level - never strung across or laid on planks.
- GFCI strategy: The cottage panel side of the feeder doesn't have a GFCI. The dock receptacles and any in-water lighting fed from the boathouse sub-panel get GFCI breakers in the sub-panel, not a GFCI receptacle at the far end. Detail in our dock and boathouse post.
- Equipotential bonding: Metal dock frames, ladders, boat-lift hardware, and railings within 3 metres of the water bond together with #6 AWG and back to the cottage grounding electrode. This is the part the inspector specifically checks at the boathouse.
- Sub-panel location: Inside the boathouse, mounted above the high-water line with a documented margin. Not in the wet level. Not on the dock itself.
Scenario four - the sauna shed
Electric saunas are a real cottage trend right now, and the electrical scope is bigger than owners expect. A 6kW barrel-sauna heater is a 30A 240V dedicated circuit. An 8kW unit is a 40A circuit. The shed itself usually has a light, a couple of receptacles, and the heater - and the heater dominates the load.
- Feeder size: 60A is enough for a single-heater sauna shed. 100A only if you're combining the sauna with another use (changing room, hot tub).
- Run method: Same as the bunkie - PVC and RW90, trenched to 600 mm.
- Sub-panel location: NOT inside the sauna room itself. The sub-panel goes in an adjacent vestibule or on an outside wall in a sheltered position. The OESC has specific rules about electrical equipment in saunas and the panel does not belong in the hot box.
- GFCI exemption: The sauna heater itself is exempt from GFCI on its dedicated circuit (manufacturer-specific - check the heater documentation). Receptacles and lighting inside the sauna are not exempt. Get this wrong and the heater nuisance-trips every cycle.
- Disconnect: Within sight of the heater. Often the sub-panel itself satisfies this.
The conductor decision - PVC plus RW90, or TECK90
This comes up every cottage job:
- PVC with RW90 conductors is cheaper per metre, easier to land at the sub-panel, and the standard choice in workable soil. It's also re-pullable if you ever need to add a conductor - a real advantage at a cottage where future loads keep arriving.
- TECK90 direct-buried wins where the soil is rocky, the run is short and direct, and the install schedule is tight. The armoured cable is its own mechanical protection and the trench can be more aggressive.
At cottages we use TECK more often than at suburban houses. The Canadian Shield doesn't give you the luxury of nice straight PVC runs.
What the ESA inspector checks at a cottage sub-panel
- Trench cover depth at any visible point
- The neutral is floating at the sub-panel (not bonded to ground)
- The ground rod at the remote structure is bonded with the right conductor and gauge
- Bonding back to the main service grounding electrode is continuous
- The sub-panel cabinet is bonded and the cover ground continuity is intact
- For boathouses, the equipotential bonding network around the dock
- Branch circuits inside the structure - AFCI/GFCI where required
- Working clearance at the sub-panel
When to call us
If you have a bunkie going in, a garage upgrade in the works, a boathouse that's been on an extension cord for years, or a sauna shed on the wish list, we do cottage and residential electrical across Huntsville, Bracebridge, Gravenhurst, Port Carling, and Baysville. Most cottage sub-panel jobs pair with a look at the main panel - sometimes the right job is a service upgrade and a sub-panel together. Send us a photo of the main panel and a description of where the new structure is. Request a site visit.