What is the size of the relay for the xB foglights?

 

The OEM fog light relay plugs into an existing board, and is protected by a 10 Amp fuse, so the relay can handle at least that. At 55 Watts each, which is a common size for fogs, that is a little bit more than 9 amps at 12 volts.
If you are talking physical size, I would say about a 1-1/4" cube, would be my best guess having put one in, but it was a while ago.

 

i was wondering what the rating of the realy is, I am utilizing the exsisting wiring for some other modifications.

 

Since it is an OEM built for fog lights on the xB, I don't believe it stated a rating on it like it would if you bought it from Radio Shack. It is a bear to pull out and put back in, or I would check it. Getting that relay in is the most difficult part of installing the OEM fog lights, by far. I used the existing wiring for my aftermarket (as in: not specifically for the xB) fog lights.