Can both 16 and 18 gauge wire be used in rewiring an antique Mogul socket?

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Old 07-09-13, 05:09 PM
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Can both 16 and 18 gauge wire be used in rewiring an antique Mogul socket?

Hi everyone,

I'm rewiring a ca.1930's "reflector" lamp which uses a mogul socket in the middle as well as three lights around it. Everything was wired with 18 gauge wire when I found it.

On the base, one switch operates the mogul bulb, another switch lower on the base operates the three medium socket bulbs. The picture below shows the unit without the mogul portion attached.

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Since I will be using a mogul bulb (100/200/300W) I thought I should rewire with 16 gauge. However, part way through this project, I've realized that the 16 won't fit through the small shaft that leads out from the centre to the three lights!

I'm totally new to wiring. I think I've heard that on one circuit it's fine to use various gauges of wiring SO LONG AS the wires can handle the load (that is, you can go up to heavier gauge, but not down to lighter gauge).

My concern is that power coming through a 16 gauge wire to a 300W bulb will need to go through the the 18 gauge on it's way into and out from the bulb, and - I don't know what would happen...fire? insulation around the wires melting? short circuit?

[I thought I might just be able to drill larger holes, but there's not enough metal. I tried to separate the wires and jam them through separately, but no go]

Any wisdom or thoughts?
 
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Old 07-09-13, 06:17 PM
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I hope you realize that finding 100, 200, 300 watt mogul bulbs is soon going to be very difficult, if not impossible as they have essentially been outlawed.

That stated, ordinary #18 lamp cord is good for about 7 amperes. A 500 watt 120 volt bulb takes just a bit over 4 amperes so from that standpoint you are fine. I would rather that you try to find some #18 fixture wire as it has a much higher temperature rating on the insulation. Those big bulbs put out one heck of a lot of heat.
 
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Old 07-09-13, 07:03 PM
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Furd, thanks for your thoughts:

"#18 fixture wire as it has a much higher temperature rating on the insulation."
Higher temperature than 16AWG?

I have a supplier in the area that sells them for four dollars each. I've also got an adapter so I can use medium sized bulbs, but the lo-med-hi mechanism of the mogul socket is lost.

mogul bulbs "... have essentially been outlawed."
Tell me what you mean.
 
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Old 07-09-13, 07:12 PM
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Well they do make 3-way CFLs so with the adaptor you should be good to go when your source runs out.
 
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Old 07-09-13, 07:25 PM
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Not just mogul based bulbs but all incandescent lamps will soon be a thing of the past as lighting is shifting to CFL (compact fluorescent lamps) and LED lamps.

Incandescent lamps are huge power wasters in the watts per lumen figure.
 
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Old 07-09-13, 07:29 PM
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Standard plastic insulated lamp cord is designated type SPT by the National Electrical Code (NEC). I don't have my NEC handy right now so I can't give you specifics but it is the insulation, not the wire size, that determines the maximum operating temperature. Type SPT has a low temperature rating and there are several insulation types used with fixture wire that have much higher temperature ratings. You might have to go to a shop that repairs lamps to find it though.

As for the bulbs being outlawed...I believe it is in the Energy Policy Act of 2005 that mandates the manufacturers of incandescent light bulbs to reduce the amount of power used in the bulbs. Many bulbs will simply be discontinued, I think the standard 100 watt bulb has already been discontinued. I can't state with absolute certainty that the three-level moguls will be but I suspect they will be discontinued.
 
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Old 07-10-13, 09:00 AM
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Originally Posted by ray2047
Well they do make 3-way CFLs so with the adaptor you should be good to go when your source runs out.
They do not make 3-way mogul-incandescent adapters. They once did, but no more. They are *extremely* rare.

Please read:
Mogul Three Way Light Bulb Adapter 3 Way Mogul to 3 Way Standard Base | eBay

Originally Posted by Furd
I can't state with absolute certainty that the three-level moguls will be but I suspect they will be discontinued.
I'm sure they will, just not as soon as ones like the 100-watters. They're a specialty-type lamp without an analogous replacement in either CFL or LED, so they'll probably stick around awhile longer. I buy these bulbs for myself and for lighting customers in my shared business and I haven't gotten any alerts or warnings that the supply is going to be cut off.

These "mogul torchieres" are very ubiquitous and I do not doubt for a second that there may literally be millions still in service.


As far as fixture wire, no need to go to a lamp store/restorer. There are two main online wholesale suppliers - B&P and Grand Brass.

You can get 18ga. SF1, which is 200C rated.

white
Grand Brass Lamp Parts:WI18SF1W

black
Grand Brass Lamp Parts:WI18SF1B


Lamp Parts, Lighting Parts, Lamp Glass and Chandelier parts - Grand Brass Lamp Parts and Lighting Parts Super Store
 

Last edited by Nick D.; 07-10-13 at 09:18 AM.
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Old 07-10-13, 12:16 PM
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It sounds from Furd
I would rather that you try to find some #18 fixture wire as it has a much higher temperature rating on the insulation.
and Nick D.
You can get 18ga. SF1, which is 200C rated.
that I need to get new wire. It would save me some fuss to use what's there, especially if, as Furd mentioned, 18-2AWG SPT-1 allows loads up to 7A.

I think all I need is 3.5A! (300W mogul bulb on with three 40W bulbs. P=VI, where I'm assuming V to be 120V.) Can't I just keep em? I sound like a boy who just found a puppy.
 
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Old 07-10-13, 04:23 PM
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You are missing the point. It is not an Ampacity issue, it is a heat issue. The 300 watt incandescent releases a huge amount of heat and a certain amount of that heat WILL go to the lamp socket. Using anything but a high temperature fixture wire is taking a chance that the wire insulation will be damaged.

Do you really want to take the chance of burning up your lamp and maybe your home?
 
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Old 07-10-13, 06:12 PM
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I hope you realize that finding 100, 200, 300 watt mogul bulbs is soon going to be very difficult, if not impossible as they have essentially been outlawed.
I just bought one as a backup for our floor lamps that take these. Not only have Mogul base 3-way light bulbs not been outlawed - no bulb has been - they're not even on the endangered species list.

Simy, #18 AWG lamp cord will handle the load.
 

Last edited by Nashkat1; 07-11-13 at 12:04 PM.
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Old 07-10-13, 07:38 PM
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Furd, I appreciate your concern. Thanks, Nashkat for your input.

Have any of you had insulation that melted due to over heating wire? I'll be honest. I'm tempted to experiment to see what tolerances 18-2 SPT-1 has under this load. I'm curious about what will happen to the insulation/wirenuts/lamp casing/etc.

What might fire look like in an electrical debacle such as the one Furd is concerned about?
 
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Old 07-10-13, 08:21 PM
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Not on;y have Mogul base 3-way light bulbs not been outlawed - no bulb has been - they're not even on the endangered species list.
Incandescent light bulbs are most assuredly on the endangered species list. While I was wrong as to the Congressional act (it was in 2007, not 2005) the incandescent bulb is being phased out world wide. The only question is what timetable. Although Wikipedia is perhaps not the most authoritative source (there are others if you do a Google for phase out of incandescent bulbs) here is the link that describes the actions around the world. Phase-out of incandescent light bulbs - Wikipedia, the free encyclopedia

It was only by last minute congressional action in December of 2011 that the phase-out was stalled in the US. Trust me, this issue WILL be revisited.


Simy, you may do whatever you desire. You don't live next door to me.
 
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Old 07-11-13, 09:04 AM
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Incandescent light bulbs are most assuredly on the endangered species list. While I was wrong as to the Congressional act (it was in 2007, not 2005) the incandescent bulb is being phased out world wide.
That may be the practical effect, at least in the short term, but it is not the regulatory intent:
When the U.S. Congress passed the Energy Independence and Security Act of 2007, they required that new light bulbs that produce between 750 and 1,049 lumens must use no more than 43 watts of power, effective January 1, 2014. That's a reduction of almost 30% in the amount of power consumed. Considering how many of these light bulbs have been in use, that's a significant reduction in energy needs as the older bulbs are replaced.

Wait a minute. A standard 60 watt light bulb puts out about 800 lumens. So does this mean that the Congress essentially outlawed them?

Yes and no. If a standard incandescent light bulb can be produced that meets the new energy standard, it would be approved. The practical answer, though, is that that's not likely to happen.

[SUB]Source: Google search[/SUB]
In addition, many special-use bulbs, specifically including 3-way bulbs, are exempted from the Act. See the Energy Independence and Security Act of 2007. The section on lamps (light bulbs) starts on page 82. It's Section 321. The exemption for "A 3-way incandescent lamp" is near the top of page 83.
 
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Old 07-11-13, 09:19 AM
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I'm rewiring a ca.1930's "reflector" lamp which uses a mogul socket in the middle as well as...
Originally Posted by Furd
it is a heat issue. The 300 watt incandescent releases a huge amount of heat and a certain amount of that heat WILL go to the lamp socket. Using anything but a high temperature fixture wire is taking a chance that the wire insulation will be damaged.

Do you really want to take the chance of burning up your lamp and maybe your home?
Have any of you had insulation that melted due to over heating wire? I'll be honest. I'm tempted to experiment to see what tolerances 18-2 SPT-1 has under this load. I'm curious about what will happen to the insulation/wirenuts/lamp casing/etc.
No. In a ceiling box fitted with a flush-mount fixture that had been overlamped for wears, I've had to repair melted insulaation. But never in a torchiere lamp. Contrary to Furd's suggestion, almost no heat from the Mogul-base lamp, installed base down, will go down to the wiring. That's what your lamp was wired with originally, right? How many years has it been working safely with that wiring?

What might fire look like in an electrical debacle such as the one Furd is concerned about?
IDK. I've never seen one. The mogul-plus-three lamp my parents bought in the 1930s, which I rewired with 18-2 zip cord in the 1980s, is still working safely in our living room today. When I rewire the one I found in a discard pile a while back, I'll use that wire in it too.
 
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Old 07-11-13, 12:09 PM
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Simy, a quick technical question: Do you know how to identify the neutral conductor in lamp cord, how to make sure it's connected to the proper part of each lampholder, and how to make sure the plug will always connect that wire to the neutral in the receptacle?
 
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Old 07-11-13, 12:21 PM
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That's what your lamp was wired with originally, right? How many years has it been working safely with that wiring?
Yeah, it's 18-2 SPT1. Not sure how many years it was working. You can tell from the pic that started this post that there weren't even wirenuts in the housing just below the mogul socket. The connections had been mummified in electrical tape.
 
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Old 07-11-13, 12:34 PM
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Do you know how to identify the neutral conductor in lamp cord, how to make sure it's connected to the proper part of each lampholder, and how to make sure the plug will always connect that wire to the neutral in the receptacle?
Ribbed to silver; again, the terminals on the medium-socket lamps have both brass and silver so there should be no confusion; I'm obviously new to this, but I just need to make sure the hot wire coming in is connected to brass, and where it splits to give power to the lower 3 lights I need to make sure that it completes the circuit back to neutral. I've taken pictures as I've gone, and I intend to draw a diagram before I begin.
 
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Old 07-11-13, 12:39 PM
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there weren't even wirenuts in the housing just below the mogul socket. The connections had been mummified in electrical tape.
So that's an improvement you can make, right? BTW, the insulation used on lamp cord these days is better than the insulation that was used when that lamp was new.

Do you know how to keep the polarity straight as you re-wire your classic lamp, and why doing that is important? If you're using a screw-terminated plug, do you know how to tie an underwriters knot? I tie one of those under each lampholder too, but it's not as critical there.
 
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Old 07-11-13, 07:51 PM
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Do you know how to keep the polarity straight as you re-wire your classic lamp, and why doing that is important?
I understand that if the polarity is reversed it would make the contact between wire and bulb neutral and the casing hot, which could result in shock. Sticking to neutral/ribbed to silver screw is going to keep this from happening, no?
Yes, I've seen the underwriter's knot and it will be relevant for the lamp I'm refurbishing.

You guys have all been really helpful. Much appreciated.
 
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