Lamp life too short!

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richwaskowitz

Senior Member
Location
Shelby Twp. MI, near Detroit
I recall that at one time one could buy a device that could be inserted in a medium base Edison lamp socket, behind the lamp, that would extend incandescent lamp life. The device's resistance would decrease as the lamp heated up, thereby lessening the inrush that pops the filaments. I have 6 can lights with 15 watt lamps in my soffit on the front of my house (20 feet up) that are constantly burning out (average about 4 months). I have tried to get 130 volt lamps to no avail. Anybody know what I am referring to?

Know of any other tricks that could help, like placing a diode in the circuit to half-wave the lamps?
 
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pwhite

Senior Member
Re: Lamp life too short!

it has been a while but yes. it is an inductive circuit that looks like 2 quarters thick. sorry, but i can't for the life of me remember the name or manufacturer. i will call an old friend and see if he can help. if you find the manufacturer, e-mail me, 130 volt lights in my area are hard to find.
 
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bennie

Esteemed Member
Re: Lamp life too short!

I use a lot of compact flourescent lamps both inside and out. I get 5 years at least.
 
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caj1962

Senior Member
Re: Lamp life too short!

If these lights are switched try putting a dimmer in its place. This will lessen the voltage to the lamps giving them a much longer life. If you use Bennies idea of flourescents they may not light up as bright when it is really cold outside.
 
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jerryb

Senior Member
Re: Lamp life too short!

I believe the devices that were inserted into lamp sockets were discontinued. The problem came from the fact that the button took up too much room inside the socket causing the outer edge of the lamp socket to be exposed. If the lamp socket wires where reveresed by mistake then the exposed edges of the lamp socket could come in contact with a person's hand causing an electrical shock. This ended up being a UL problem.
 
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luke warmwater

Senior Member
Re: Lamp life too short!

Different companies make compact fluorescents that are made for cold temperatures and they work great.
 
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satcom

Senior Member
Re: Lamp life too short!

Have you checked to see if there is a bootleg neutral on that circuit, most of the short lamp life problems we find,are usually loose neutral or bootleg neutral.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: Lamp life too short!

Bootleg neutral.

Using grounding conductor for neutral

or

A neutral that has accidentally been connected to ground at a point other than the service.

At least that is how I take it when I read it. :)
 
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satcom

Senior Member
Re: Lamp life too short!

We had someone passing himself off as an electrician, doing recess lighting, great prices, he would take his can feed and connect the hot leg to the existing wall switch, which had no neutral in the box, and then connect the neutral wire to the box ground. (We call this a bootleg neutral), the lights work so the homeowner thinks he did the job right, however when the owner has to replace bulbs every 3 months, they usually call an electrician.
 
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ronson

Member
Re: Lamp life too short!

would you also call a "bootleg" neutral a neutral that is picked up from a different ckt from the one your hot is on?
 
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drg

Senior Member
Re: Lamp life too short!

ronson, thought this was a good question , would say that article 210.4 Multiwire branch circuits explains using a neutral like this.

A point should be made that in a multiwire branch circuit it is required that the 2 hot conductors shall have simultaneous disconnection with a 2 pole circuit breaker or 2 single pole breakers with an approved tie handle.

A situation where a neutral is just picked up at random and "shared" by 2 circiuts sounds dangerous for obvious reasons..........perhaps some call this a bootleg.

Im just as curious as you are on this one, I have been calling these a "shared neutral" and these types of circuits I do not like to come across

John.


:)
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: Lamp life too short!

You are right that you can use a common neutral with a multiwire branch circuit as described in 210.4.

You can not just grab that common neutral anywhere in the building, the 'hots' & neutral must go back to the panel in the same raceway or cable.

There are some exceptions to this, and 300.3(B) would be the place to start looking for these. :)

Now what about a 'shared' neutral, say one neutral conductor size 8 AWG as the 'shared' neutral for two 20 amp circuits both on the same phase? ;)
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: Lamp life too short!

Originally posted by satcom:
most of the short lamp life problems we find,are usually loose neutral or bootleg neutral.
Click to expand...
I can certainly understand how a loose neutral at the service or of a multiwire branch circuit could shorten lamp life by exposing the lamp to over voltage.

But how would a bootleg neutral, or a loose neutral of a two wire circuit effect lamp life? :confused:

[ March 07, 2004, 05:45 AM: Message edited by: iwire ]
 
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drg

Senior Member
Re: Lamp life too short!

What about it then ?

Just kidding Bob, I don't know how to answer that one , I have a thought though.........is it that the #8 carrys "lets say" 40 amp back through as a unbalanced load would cause the 20 amp breakers to make noise???
Im just guessing so don't get wild with me here. :)
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: Lamp life too short!

The 'shared' neutral issue comes up from time to time and no one has really come up with any code against it.

What if I run one 8 AWG neutral and six 12 AWG 'hots' each on 20 amp breakers using each phase twice, A,A,B,B,C,C.

Basically two 3 phase multiwire branch circuits using one 8 AWG neutral, in the worst case of loading the neutral could only be subjected to 40 amps of load.

Is it a violation? :D

[ March 07, 2004, 06:21 AM: Message edited by: iwire ]
 
H

hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
Re: Lamp life too short!

Bob isn't a neutral on a "Y" transformer always current carrying? would this add even more current to your multi-wire circuit neutral? I never thought about that one

[ March 07, 2004, 01:05 PM: Message edited by: hurk27 ]
 
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