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dc lamps #37814 05/07/04 05:49 PM
Joined: Nov 2000
Posts: 246
R
rmiell Offline OP
Member
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

Work Gear for Electricians and the Trades
Re: dc lamps #37815 05/07/04 07:12 PM
Joined: Jan 2004
Posts: 66
C
cpalm1 Offline
Member
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

Re: dc lamps #37816 05/08/04 12:34 AM
Joined: Apr 2002
Posts: 2,527
B
Bjarney Offline
Moderator
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.

Re: dc lamps #37817 05/08/04 11:10 PM
Joined: Feb 2003
Posts: 939
F
frenchelectrican Offline
Member
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?)

Re: dc lamps #37818 05/09/04 04:51 AM
Joined: Aug 2001
Posts: 7,520
P
pauluk Offline
Member
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.

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

[Linked Image from joetedesco.com]


Joe Tedesco, NEC Consultant
Re: dc lamps #37820 05/10/04 01:56 PM
Joined: Nov 2000
Posts: 246
R
rmiell Offline OP
Member
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

Re: dc lamps #37821 05/11/04 11:57 AM
Joined: Oct 2003
Posts: 152
M
Mean Gene Offline
Member
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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