# What is the best type of fuse for AC disconnect box?



## joe citizen (Oct 26, 2011)

I just had a new AC unit installed this spring and it looks like the the fuses in the disconnect box are just cheap standard non current limiting fuses. Im wondering if a current limiting fuse would be better protection and if it should be a standard fuse, delay fuse or fast acting? Any opinions on this?


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## gregzoll (Dec 25, 2006)

By what standard are you saying that they are cheap? Is there a basis that you are going by, to make this assumption? Have you been blowing a bunch of fuses every time the a/c kicks on, and having to replace every time?


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## REP (Jul 24, 2011)

Try watching your elec meter when the a/c starts.You will notice a spike or a movement ever so slight.That is because there is a spike when the two motors kick on.For this reason I have always used time delay fuses to avoid unneeded blown fuses durning the year.


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## biggles (Jan 1, 2008)

time delay fuses are the norm ....:thumbsup: when any motoer stat eithe rit be SH house exhaust or a 10 ton compressor it draws 10X the amperage to turn over(as per a car startet to turn an engine) a TD fuse will take that milleee second of heat and then saftey cover the running amperage.... below amperage


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## joe citizen (Oct 26, 2011)

gregzoll said:


> By what standard are you saying that they are cheap? Is there a basis that you are going by, to make this assumption? Have you been blowing a bunch of fuses every time the a/c kicks on, and having to replace every time?


No, I haven't blown any fuses. Just wanted to make sure I had a fuse that offered the best protection in case something did happen.


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## joe citizen (Oct 26, 2011)

Thanks REP and biggles for the info.


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## beenthere (Oct 11, 2008)

For motor loads. A time delayed fuse is needed. The fuse offers no real protection to the motor/motors. The motor's internal over load device i really the only thing that protects it. Unless a true motor over load device is added.

http://gainesvilleindustrialelectric.blogspot.com/2008/06/motor-overload-protection.html


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