What You'll Learn

  1. Introduction
  2. Decoding The Cord
Decoding The Cord
That inscrutable string of letters on the packaging (SJTW, SJOW, etc.) offers critical information about the extension cord inside. Here's a quick explanation of the meanings:

AWG: American Wire Gauge. Designates wire diameter. The lower the number, the thicker the wire.

W: Withstands wet and cold conditions outdoors.

T: Thermoplastic/vinyl jacket. Inexpensive, but stiffens in cold and is more vulnerable than rubber.

E: Elastomeric rubber jacket. Resists abrasion and stays flexible in cold.

O: Oil-resistant. Safe for garage floors.

SJ: Junior Service. The cord you'll find on store shelves. Indicates a heavy-duty, rubber-insulated copper wire with a 300-volt capacity.

Limits on Length

The current-carrying capacity of an extension cord diminishes as it gets longer. For tools that draw 10 amps or less, a 16-gauge cord up to 100 feet long will suffice. But tools that use between 11 and 15 amps need at least a 14-gauge cord no more than 50 feet long. Here are sample minimum cord sizes for some common tools:

Circular saw (15 amps): 14 gauge
Reciprocating saw (13 amps): 14 gauge
Leaf blower (12 amps): 14 gauge
Chain saw (10 amps): 16 gauge
Lawn mower (8 amps): 16 gauge
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