# Difference betwwen P21/5W (1157) and P21W (1156)?



## Helicon Twist (Jul 10, 2002)

They're the same physical size and the same application (turn signals typically). They both have two tabs by which to screw into the bulb sockets.
The difference is in the location of the tabs. I've heard that an 1156 (P21W) bulb can be forced to fit in an 1157 (P21/5W) socket by sanding off one of the tabs.
Is this safe? Are there more substantial differences between these two bulbs (power consumed, heat generated, life span)?
This questions come from a lighting upgrade for a New Beetle. I'm upgrading the US-stock amber side marker/front turn signals to Euro all-clear ones. I wanted to use Phillips SilverVision bulbs, since they look silver but light up amber. This would maintain a "clean" look while maintaining street-legality. However, the SilverVisions are size P21W; the Beetle sockets are for size P21/5W.


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## PerL (Jan 9, 2001)

*Re: Difference betwwen P21/5W (1157) and P21W (1156)? (Helicon Twist)*

The big difference between a P21W and a P21/5W is that the latter is a dual filament bulb. This means that you have both a 5 watt and a 21 watt filament in the same bulb. The SilverVision is just a single 21 watt bulb, which means that there is no 5 watt filament in there. 
If you file off one of the two bayonet pins, your bulb will hit both contacts in the socket at once, causing the 21 watt filament to burn constantly (when parking lights and headlights are lit), and also cause all kinds of weird things to both your parking lights and turn signals. I suggest you try to get a pair of Euro bulb sockets as well, p/n 1C0 945 267.


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## Bora20 (Feb 13, 2000)

*Re: Difference betwwen P21/5W (PerL)*

Most NA spec cars come with P21/5W bubls because of the dual purpose parking light/signal light capabilities.
Most, if not all European cars, have seperate bulbs for each function, therefore, making them safer. ie. you know when someone is turning because you only see amber from the car when they are turning.
To make your Beetle perfectly legal using Silversvision bulbs, you will need a seperate front parking light. These can be found in the Euro-spec headlights.


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## Helicon Twist (Jul 10, 2002)

The thing is, the turn signals and parking lights are the same unit on the NB. The parking (or "city") lights aren't in the headlights. Oh well, I'm better informed nonetheless http://****************.com/smile/emthup.gif


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## Lumalux (Jun 29, 2001)

*Re: Difference betwwen P21/5W (1157) and P21W (1156)? (Helicon Twist)*

The P21/5W is the European version of the dual filament lamp. It is 21 watts for the major filament (brake or turn application) and 5 for the minor filament (parking lamp).
The closest retrofit for the P21W is the 1073, and for the P21/5W it's the 1034, but these two lamps can be hard to find.
The 1157 is a U.S. spec lamp which is 27 and 8 watts. Although the light output is roughly the same, the 1157 is designed to last longer. The 1157 is rarely used in new applications since the all-glass wedge base lamps (3057, 3157, 3357, 3457, etc.) perform better, are cheaper to manufacture, and can be installed more easily with automated assembly equipment.
There are other performance characteristics such as luminescence and nigrescence rates that distinguish these two lamps. The European-spec lamps always have a nickel-plated brass base which is superior to brass or aluminum.
You should not attempt to modify the indexing pins on a lamp that is not designed to fit in a particular socket. Sanding one pin will cause the lamp to seat improperly in the socket.


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## Bora20 (Feb 13, 2000)

*Re: Difference betwwen P21/5W (Lumalux)*

The european Beetle bulbs have to parking lights in the headlights


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## Helicon Twist (Jul 10, 2002)

*Re: Difference betwwen P21/5W (Bora20)*

quote:[HR][/HR]The european Beetle bulbs have to parking lights in the headlights







[HR][/HR]​So do the US ones (in the bumper corner lights), if mod'ed with a Euroswitch http://****************.com/smile/emthup.gif



[Modified by Helicon Twist, 1:14 PM 10-20-2002]


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## PerL (Jan 9, 2001)

*Re: Difference betwwen P21/5W (Helicon Twist)*

You certanly dont need a Euroswitch to install parking lights in the head light units!!!


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