Inline fuse wiring for STC -1000 questions.

Building up my dual (heat and cool) temperature controller based off the STC -1000. I've got the wiring diagram from a few sources and no issues.... EXCEPT, I would really like to wire in a 10A fuse inside the project box on the hot wire before it hits the controller. Seems easy enough right? Well...

1) I know very little about wiring

2) Radio Shack had a crappy selection of fuse holders n fuses

3) I don't want my house to burn down.

Will what I found be acceptable? If not please tell precisely what I need and a source (if you can). I got some lagering to do!

Fuse holder:
Automotive Inline Fuse Holder
250v AC 10A

Fuses:
Slow Blow
32v 10A

There were no 110v fuses in that size and seeing as the STC will be running off house current, that's what I thought was necessary. The amperage is good. Confused.....

Pics below

 

I would look for a fuse rated for 120 V AC if possible.

Are you trying to protect the STC-1000, or the STC-1000 and the two 10A loads on it?

Personally, I don't have any fuse in either of my temperature controllers because I rely on the 15A house circuit breaker. If the STC-1000 draws an overcurrent it is because it has toasted itself, and a dedicated fuse won't do much good for wiring protection unless it is a 1A fuse. If an appliance plugged into the STC-1000 draws too much current it will trip the house breaker.

 

I think the ceramic heater and chest freezer will be fine, more interested in making sure the STC doesn't get fried/overheat.

I couldn't find any damm fuses over 30v in that form factor. You think that inline housing is adequate tho? Might just have to shop around online some more on the fuses....

 

The purpose of the fuse is not to protect the STC-1000, rather it is to protect the wiring from the STC-1000 drawing too much current - which it does if it fails. Don't worry about it.

 

As these guys have said, your fuse will be almost purely for show. The situation in which your fuse would blow would be if your STC breaks, draws a lot of current, blows your fuse. The situation without a fuse is... STC fails, draws a lot of current, trips your breaker. STC will still be broken in either scenario.

P.S. I run 5 STCs and have never had a breaker tripped or had one fail. I run 8-9 amp loads on them, no problem. Just be sure you are wiring it up correctly. I.e. use the STC switch inline with the hot wire of your appliance.

 

Ok copy that, scratching fuse idea.

 

The voltage rating is a maximum, i.e. The above fuse will work at 240VAC or 120VAC. It’s an AGC, which is fairly fast. You could use it in a car, but it might fail.

Low voltage fuses are mostly for automotive applications. You want something that handles temperature and vibration. Fuse elements are fat and slow. Slow is good for high start currents like motors and lights.

A fuse melts when the current is too high for too long. It doesn’t care about the voltage.

I measured the current on the thing, it’s 15ma on, 12 ma off, or a little less than 2 watts @120VAC. So even with a ½ amp fuse, it would take like a 3500% overload to blow the fuse.

I just took one apart and there is no external fuse per se. There is a narrow PC trace that would function as a fuse if the transformer had a primary short. Transformers generally are designed to fail if they get too hot.

In summary, don’t worry about it, the other guys are right.