There is no universal safe device count for a wall outlet. What matters is total circuit load, receptacle capacity, and how appliances are connected. A phone charger draws very little compared with a space heater, hair dryer, or microwave, so simply counting plugs can be misleading.
Pay attention to high-load appliances
Hair dryers, kettles, space heaters, and countertop ovens can use a large share of a household circuit by themselves. Avoid running them together on the same circuit when the appliance instructions or installation do not support it.
A duplex receptacle is still on the same circuit
Two receptacle openings do not double available power. Other outlets in the room may share the same circuit, so total load cannot be determined by looking at one receptacle alone.
Do not use adapters to hide an overload
An adapter that turns two openings into six does not increase wiring capacity. If many devices need permanent power, distribute loads or have appropriate receptacles installed professionally.
A hot outlet or tripping breaker means stop
Do not keep resetting a breaker that trips again or use a hot or discolored outlet. Disconnect loads and arrange inspection if the problem persists because a loose connection can overheat even without an obvious theoretical overload.
Sources
- U.S. Consumer Product Safety Commission — Electrical Safety — Household electrical safety, overloads, damaged connections, and warning signs to stop use.