You can test those bulbs by the touching the contacts of the base of the bulb to the contacts of a 9 volt battery. Since those C6 bulbs are about 12 volts.
Many years ago my grandmother gave me a big box of these lights and I use them every year…..but mine are not modified and spliced. They have the original 8 sockets per string. I have since purchased a dimmer and dim them slightly to help the bulbs burn slightly cooler.
@@sbcinema use a Variac because there not fused or polarized I have 24 strings of 8 lights none are altered only 2 have been repaired they have 7 lights rather than 8 I use heat shrink tubing rather than electric tape that's why I run the strings on a Variac
The series strings were mostly 8 sockets. The NOMA bubble lites had 9 sockets to prolong the life of the lamps. With the 21 series string, the lamps will last forever.
Because each string is a series circuit, in the short string 120 volts is divided by 8 bulbs each getting about 15 volts per bulb.In the longer string, 120 volts is divided across 21 bulbs each getting closer to 6 volts. As you observed, the bulbs in the longer string are no where near as hot and the color is richer. The longer string is the equivalent of using a dimmer and the bulbs will last a lot longer than those in the short string. Dedicated collectors would never plug an 8 or 9 bulb string into a wall outlet. Instead, we use dimmers to lengthen the life of the bulbs. Some collectors merge sets, as did the owner of the 21bulb string, to make it easier to decorate a tree with the longer line and to avoid the need for a dimmer. 21 bulbs may be too many. As you can see, the darker blues do not light very well at 5 or 6 volts of energy. In the 1930s and 40's when these lights were most popular, few houses actually received a line voltage of 120 volts. That may be one reason that they were sold in short strings. Also, the lighting companies wanted to sell replacement bulbs. Finally, some people might want "super bright" bulbs. Thanks for showing the temperature of the C6 with a full 15 volt charge. 156 f. As a point of reference, book paper ignites at about 450 f. Still, 156 will burn the fingers.
I have 24 strings I run mine on a Variac mine don't have splices the strings you have are a huge fire risk I would be scared to even plug them in i stay away from buying Botched up strings for safety and botched up strings also be careful with milk glass bulbs some are carbon tipped and run less than 15 volts Update I just got 5 more of these there similar to your condition but when I looked at the splices they have solder just needed to replace the tape
