The effect of temperature on the resistance of a tungsten filament is not exactly an unknown and there's no reason to horse around trying to measure it yourself. Just read the dang literature. It's been done.

that's exactly the way it is.

cold resistance of bulbs especially larger one's can put a large duty on dc/dc converters.

 

Where would this literature be found? (I haven't looked)

It's hard to measure a filament.

What else can be done? You can't go by the rated watts.

A 100 watt 120vac GE bulb draws a little less than .7 amps @ 120vac.

 

I think Ohm's Law works for AC as well as for DC.
If a bulb draws 1A at 120VAC then the resistance would be 120Ω.

If the bulb draws 0.7A, the resistance is 171Ω.
If the bulb draws 0.8A, the resistance is 150Ω.
If you go by wattage, a 100W bulb would be 144Ω.

 

A number of years ago I developed a circuit the eliminated the surge current in 12V RV or 12V incandescent bulbs. One of the side benefits was that the length of the life of the on/off switches was also increased. I still have two RV fixtures on my bed for reading. One bulb has been in use for over 10 years. Both on/off switches are original switches.

And yes the surge current was measured to be approximately 10 times the normal operating current. As a side note the lamps are operated via batteries charged with solar panels.

 

All this is somewhat moot since the incandescent bulb is going the way of the Dodo, at least as far as standard residential lighting is concerned.

 

I think Ohm's Law works for AC as well as for DC.
If a bulb draws 1A at 120VAC then the resistance would be 120Ω.

If the bulb draws 0.7A, the resistance is 171Ω.
If the bulb draws 0.8A, the resistance is 150Ω.
If you go by wattage, a 100W bulb would be 144Ω.

What I'm getting at is my 100 watt bulb is an 84 watt. Must be an energy saver.

Ie. same lumens. Lower watts.

Should be labeled 100 watt equivalent!

 

The bottom line for the OP if he is still visiting this thread is he has to measure the current while the bulb is in circuit and being lit.

 

What I'm getting at is my 100 watt bulb is an 84 watt. Must be an energy saver.

Ie. same lumens. Lower watts.

Should be labeled 100 watt equivalent!

Could be a 100 watt equiv.

See this article from Fluke about 100 watt tungsten, 'halogen', CFL and LED. Your amp measurement is there - not an indepth article but, you should be reading 0.833 amps on that 100 watt bulb.

http://www.fluke.com/fluke/caen/com...Say-Goodbye-to-the-Incandescent-Lightbulb.htm

 

A number of years ago I developed a circuit the eliminated the surge current in 12V RV or 12V incandescent bulbs.

Once upon a time (somewhere in the 1990's), I bought some little, button shaped objects, to suppress the initial surge in incandescent bulbs. (You put them in the socket before you screw the light bulb in.) I wish I knew where to buy some now.

Any clue what they are called or where to buy them?

 

I remember them.

Thought they were diodes.

I guess not!

Bulb misers.

http://www.sodahead.com/living/a-2-...lb-life/question-2565169/?link=ibaf&q=&esrc=s

 

Phooey! Not a word about where to buy them.

 

bulb miser brings up zilch

 

Oops can't think of what they're called.
CL-50 or CL-60 are the ones I have.

7ohm at 5amps
1.6ohm at 1 amp

and
10ohm at 5amp
.18 at 1 amp

They're disk shaped. Form the leads and a mold for some potting material.

 

I'm interested.
The right part in a flat, round shape, with an insulating ring that will not fracture when you screw the bulb in. Seems doable.

 

These are the CL-60s

10X1.8ohm

Something a little stiffer than silicon for potting?

 

I've noticed 480 systems are always over 500 volts now.

I went out to troubleshoot a glass coating line recently. They said things were failing atan alarming rate. It had these old german proprietary special function "relays" that kept failing and had to be replaced at an exorbitant cost. Measured the "480v" incoming power, 530V. That's high, but it's still within power company spec. Looked at the machine data plates, and the ratings of all these "relays" and the whole line, and everything in it, is rated 440v. So we are running 90v over the rating.... I told them they need a transformer the size of a school bus, or to replace all that old crap in all the cabinets, and probably all the motors and basically everything electrical with higher rated components. They opted for option 3, just keep replacing things as they break. But I did convince them to replace these proprietary relays with programmable "brick" smart relays (that I program on site), as they fail. So I have, or should have, repeat business out there.

 

Have ever replaced any proprietary octal base devices with 5 1N4006 diodes inside?

Lot of those relays, if electronic inside are easy fixes. They were a money maker for me on a concrete batch plant. I kept it running 20 years after part supply dried up.

 

I'm interested.
The right part in a flat, round shape, with an insulating ring that will not fracture when you screw the bulb in. Seems doable.

Connected one to a 100 (85) watt bulb.

Peak (and hold) reading across device is 7 volts cold.
Less than 2 hot.
Not the right device.
Close maybe?
http://www.digikey.com/product-search/en/circuit-protection/inrush-current-limiters-icl/656273

How about SL-18
http://www.digikey.com/product-detail/en/SL18 47003/570-1101-ND/2614365

Actually notice less of a jump on my analog meter when plugging in though.

 

Have ever replaced any proprietary octaI base devices with 5 1N4006 diodes inside?

Lot of those relays, if electronic inside are easy fixes. They were a money maker for me on a concrete batch plant. I kept it running 20 years after part supply dried up.

5 1n4006 ? Don't think so. When I was in machine maintenance repaired a lot of "90vdc clutch power supplies" and "fixed time delay" and "wire break sensor" octal "relays" that weren't more than a couple diodes or a 555.

But now that I'm in field service and customers pay hundreds per hour for me to be on site (I don't get hundreds per hour, unfortunately), it is actually more cost effective for them to have me replace the octal device with a smart relay, since I can do that in 30min or less. Otherwise I would have to bring the busted gadget back to the shop, crack it open, troubleshoot it, find out if we have the parts, order parts if not, receive them in, solder, drive back out, you get the picture. The Smart relays that i carry (omron Zen) only cost $150 and I carry them with me. 120v and 24v. One perfect use I've found for them is DC motor field reversal.

The only components I carry are resistors and 1n4004 diodes

 

I'm tired now. I'm checking out for a while.