# What is the difference between 20 w and 50 w 12 v halogen lamp?

Discussion in 'The Projects Forum' started by Lightfire, Jan 19, 2011.

1. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
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OK,

I have two halogen lamps. The one is rated as 12 v 20 w and the one is also 12 v but 50 w.

V means VOLTS and W means WATTS, am I correct?

OK, here's what the result I saw.

halogen lamp 12 v50 w is brigther than 12 v 20 w. But is 50 w halogen lamp consumes more power?

Apr 5, 2008
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3. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
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Thank you. But I don't know all the symbols. Can you give me the master list of symbols about electricity so I can understand it...

Apr 20, 2004
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5. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
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Thank you...

I also notice that my wire is hot (i mean a liitle bit warm), what does it means???

6. ### Gundalf New Member

Jun 22, 2010
13
0
I presume you mean the wire from the power outlet to the lamp is getting warm?

A 50W lamp draws a larger current than a 20W one (over twice as much in fact). In the same way that current heats up the filament in the lamp to make it glow, it will also heat the wire supplying the lamp.

Because the wire feeding the lamp is thicker and has much lower resistance than the filament then it won't get as hot as the filament - however a cable that is getting noticeably hot is probably not thick enough so you may want to consider finding some thicker wire as it may eventually become a fire risk.

7. ### beenthere Retired Moderator

Apr 20, 2004
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It means that it is too small for the current it is carrying. 20 watts @ 12 volts is about 1.67 amps. 50 watts is about 4.17 amps.

If it's only a bit warm, it may present no problem. If it gets hot, then things wil satrt to break down, and you may have a fire hazard. If you have put a 50 watt lamp in a fixture intended for 20 watts, that could be a problem. Copper is expensive and manufacturers only use conductors that are just heavy enough to carry the rated current.

8. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
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Yes, I am also afraid of fire risk.

The one that I felt a little bit warm is on the wire which is near in the battery... But the rest of wire, it's not.

Is there any problem???

I stayed the light on for about 10 minutes and more, and no problem about that.

No indications that there is risk of fire...

Anyway, the halogen lamp is also hot. very hot. even though i just touched it less than 1 second, I felt that my finger just get burn...

any problem or it just normal???

Apr 5, 2008
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Hello,

Halogen lamps themselves get very hot.
Never touch a halogen lamp as the grease from your finger can burn in the surface and make black spots on the quartz glass.

Bertus

10. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
21
ok thanks. but is there any problem on the wire???

11. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
Keep in mind that the lamp socket must be designed/rated for the power, too. If you plug a 50W lamp into a socket that is only rated for 20W, you will probably have a melt-down or fire.

For a 50W 12V bulb, AWG-22 is the smallest wire that you should use. You could get away with using AWG-23, but you'd have some power loss.
http://www.powerstream.com/Wire_Size.htm

[eta]
As Bertus mentioned, you should never touch a halogen lamp. If you do, you need to clean the finger oils off of it. Let the lamp cool to room temperature, and use isopropyl alcohol on a cloth or paper towel to remove contaminants from the bulb.

Apr 5, 2008
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13. ### Audioguru New Member

Dec 20, 2007
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If a piece of wire is hot at one spot then the wire is damaged at that spot and might get hot enough to cause a fire.
Replace the wire.

14. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
21
the socket that I am currently using is 200+ volts and 3 or 10 amp...

Is that may cause fire???