What Does VT and HP Switch Ratings Mean



I recently encountered a rating that I’ve never seen before on a Carling switch. The following number was printed on the side: 6A 14VT. I was grasping at straws trying to figure out what this had meant, so I did a bit of research. It turns out some older switches along with specialized switches have very particular ratings. The 14VT stands for 14V Tungsten service which means the ability to handle high initial in-rush characteristics of a tungsten filament bulb. So if one is trying to compare to something in our system that doesn’t have that particular rating, is a tungsten filament being used or is a high in-rush going to occur? If the switch load is not going to experience in-rush current, then the rating will not matter.

I also was curious as to why other switches were rated in Horse Power (highly unusual for electrical parts in my mind). It turns out that HP was and is used for the same thing happening because motors have high inductive loads. Carling has a very useful web-page for information about all of this in detail for anyone’s future reference: click here. The tungsten service is also mentioned here, so that confirms the research I found.