Thread dies - help!

[Dusty Floor]

I have some outdoor light fixtures (12V) that have 1/2" NPS threads on them (this is the thread used in many light fixtures. They are aluminum, and I've managed to break a couple of them right above the threads. I found a 1/2" NPS die and ordered it; received it yesterday, but the opening is closer to 3/4". It's clearly labelled 1/2 NPS, though.

What am I missing?

 

[BillK]

Dusty,

Pipe threads are very different than "normal" threads as far as thier sizes go. If the threads you have actually measure close to 1/2", I am betting that they are actually
1/4" NPS threads. Here is a good link that shows the sizes:

http://pipeandhose.com/node/19

 

[Dusty Floor]

Thanks. Looks like 1/4" is right. Hopefully I can trade this one in.