Our review... C7 Incandescent Christmas Light Bulbs fit C7 strings with E12 Candelabra screw-in type bases. The "steady burn" version comes in 5 watt or 7 watt, transparent or ceramic, and are rated for 3000 hours. The "twinkle" version (which blinks on & off) comes in transparent only and are rated for 1500 hours. Both versions have nickel coated bases, are 130 volt, and the color coating is double dipped for a richer color without sacrificing brightness. The C7 bulb measures 2" by 7/8" (including the base). Of the two most common Christmas lights bulbs, C7 & C9, the C7 is the smaller of the two and is commonly used in night lights.
If the wire on your strings is rated for 5 amps / 600 watts, you can connect no more than about 120 sockets together on a single run - using 5 watt bulbs, and 80 sockets - using 7 watt bulbs. If your wire is rated for 7 amps / 840 watts (SPT1), the limit is 168 sockets for 5 watt, and 120 for 7 watt. With 10 amp / 1200 watt wire (SPT2), the limit is about 240 sockets for 5 watt, and 170 for 7 watt. Exceeding these limits may blow fuses or cause the wire to overheat..
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