Plugging an extension lead into a multi-plug, or power strip, is strictly prohibited. This practice, known as “daisy-chaining,” creates a significant electrical hazard that can lead to overheating and fire. Electrical safety guidelines prohibit connecting multiple power distribution devices in a series. This article explains the dangers and provides safe alternatives for accessing power.
The Dangers of Daisy-Chaining
Connecting an extension cord to a power strip, or connecting one power strip to another, introduces a severe risk of electrical overload. Both devices are designed to handle a specific maximum current, typically 15 amps or 1800 watts. When daisy-chaining, the first device must carry the combined electrical load of every item plugged into the entire series, easily exceeding its internal wiring capacity.
This excessive current draw causes the conductors within the cord or strip to heat up significantly. Since the internal wiring of these devices is often thinner than the permanent wiring inside your walls, it becomes the weakest link in the circuit. The resulting heat can melt the plastic insulation and housing, leading to a short circuit and a fire.
Daisy-chaining violates established safety regulations. The National Electrical Code (NEC) prohibits connecting relocatable power taps to anything other than a permanently installed receptacle. Using a power strip inconsistently with its listing, such as plugging it into an extension cord, can void the manufacturer’s warranty. If a fire occurs due to improper use, insurance policies may not cover the resulting property damage.
Another technical concern is the effect on sensitive electronics due to voltage drop. Every connection point and every foot of cord adds electrical resistance to the circuit. When multiple devices are chained together, the cumulative resistance causes the voltage delivered to the devices at the end of the chain to decrease. For certain appliances, such as those with motors, a drop in voltage can cause the device to draw more current to compensate, further exacerbating the risk of overheating in the cord.
Safe Solutions for More Power Access
When you need more outlets or a longer reach, the safest approach is to use a single device plugged directly into a wall outlet. For a longer cord, purchase an extension cord of the correct length that is rated for the total load you intend to connect. For more outlets, use a single power strip that has a resettable circuit breaker and is listed by a recognized testing laboratory, such as UL.
Before plugging in any devices, you should calculate the total power consumption to ensure you do not overload the strip or the wall circuit. Most standard household circuits are protected by a 15-amp circuit breaker, and safety guidelines recommend only loading a circuit to 80% of its capacity, which is 12 amps. To find the total amperage, add up the amperage listed on each device, or divide the total wattage by the voltage (e.g., 1800 watts / 120 volts = 15 amps).
High-wattage appliances should never be connected to any power strip or extension cord. Devices that generate heat, such as space heaters, toasters, and microwaves, draw a significant amount of current and must be plugged directly into a wall receptacle. If your power needs are permanent and the existing wall outlets are insufficient, the most secure solution is to contact a qualified electrician to install new, fixed outlets.