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#37814 - 05/07/04 05:49 PM dc lamps  
rmiell  Offline
Member
Joined: Nov 2000
Posts: 242
La Junta, Co. USA
This may be a dumb question, but I guess I have not thought about it before.

Can I put a regular incandescent lamp (120v, 100watts) on a 125vdc circuit?

I looked quickly through a couple of lamp catalogs, and did not find any DC rated lamps, the voltage rating were just listed as 120v, or 12v.


thanks

Rick Miell


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#37815 - 05/07/04 07:12 PM Re: dc lamps  
cpalm1  Offline
Member
Joined: Jan 2004
Posts: 66
yes, you can put a standard bulb on that circuit. however, you may wish to use "commercial" 130V bulbs rather than 120V bulbs since your circuit is 125V


#37816 - 05/08/04 12:34 AM Re: dc lamps  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
Incandescent lamps run fine on DC. One hitch though—most flush toggle switches are AC only. For tungsten-lamp switching, a DC {“T”} tungsten-rated switch is needed. They make plenty of racket during operation …none of that quiet AC-only stuff. They are listed as AC-DC General Use Snap Switches — UL Guide WJQR.


#37817 - 05/08/04 11:10 PM Re: dc lamps  
frenchelectrican  Offline
Member
Joined: Feb 2003
Posts: 939
Wi/ Paris France { France for ...
Rick.

most indscent lamps can run on dc with out any troble but bear in mind that the dc verison will run slightly dimmer but not a whole alot but bulb life will be little longer too also.. i am not sure if you know this or not when bulb fail they do flash over pretty good btw just like 277 volts ac bulbs go out simuir idea so i dont know but i will guess you allready knew this or not put a over current device there to prevent serouis arc falut.

as far for switch use the genral usage snap switch .

merci , marc

p.s. i did work on one tug boat before it ran everything on dc before so i got pretty good idea how it react with it .


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


#37818 - 05/09/04 04:51 AM Re: dc lamps  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Filament lamps run on DC just fine, and if connected to a 125V DC supply you will obtain the same amount of illumination as on a 125V RMS AC supply.

Switches need to be the "quick-break" type for DC operation. The common "tumbler" switches used in this country when DC supplies were common employed a spring-action contact and opened and closed with a really noticeable clunk. The quiet AC-only switches will end up with burned contacts if used on DC.


#37819 - 05/09/04 08:37 AM Re: dc lamps  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
Will these switches work too?

[Linked Image]


Joe Tedesco, NEC Consultant

#37820 - 05/10/04 01:56 PM Re: dc lamps  
rmiell  Offline
Member
Joined: Nov 2000
Posts: 242
La Junta, Co. USA
Ok, Thanks guys.

These lamps will be run thru a contactor, so switching will not cause a problem.

I knew you guys would give me a straight answer!!!!

Rick Miell


#37821 - 05/11/04 11:57 AM Re: dc lamps  
Mean Gene  Offline
Member
Joined: Oct 2003
Posts: 152
Ohio, USA
Joe, what were you doing at my mother's house? [Linked Image]

She still has a few of those and they work like brand new. Amazing, for being 80 years old now.



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