Bussman 125v Fast Blow Fuses


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Old 09-12-16, 09:01 AM
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Bussman 125v Fast Blow Fuses

Hello All.
I am am building outlet that I can control with and arduino. The load only cause for 5 amps, and the arduino relay is rated at 10 amps.

Safety first I have been looking to put a 10amp fuse, looked at ceramic and looked at glass. However having never used AC fuses before I was expecting them to work in a manner of seconds.

GMA-10-R is one I was looking at, but its rated at 10A but says it interrupts at 200A, and says at 135% current 60 minutes max time. So I take this to mean if 200A went through it would interrupt nearly instantly, but at 13.5A it would interrupt any where between 0 seconds and 3600 second?

This sounds scary to me I have no idea what happens to those relays if they have 35% over current for 1 minute, 3 minutes ect.

Are there faster fuses out there? I know its not even apples to apples but I have plugged a dc load in and the fuse instantly blew. I have seen some small circuit breakers that I thought was the answer but then saw it was a china company with no data sheets so I abandoned that.
 
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Old 09-12-16, 09:18 AM
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Your interpretation is correct -- most line voltage components are anticipated to see ~20% load over the stated nameplate value on a regular basis and ~150% over the nameplate value briefly. This is to accommodate very large current spikes for short times during A/C motor start up, or moderate current overloads for a few minutes such as a toaster or hairdryer.

Based on what I've seen in furnaces and refrigerators, the relays are usually designed as a sacrificial component on the A/C power control board.
 
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Old 09-12-16, 09:27 AM
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Thank you very much. Its good to hear some feed back on the relay as well. I was hopeful that they would just fail open and not catch fire :-). Not sure my wife would appreciate me burning down the house, could be a while before she would feed me again.
 
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Old 09-12-16, 09:31 AM
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If you plug this in to a GFCI-protected circuit, while it won't protect against everything, will significantly improve the safety. A circuit with an AFCI breaker would also provide some additional protection.
 
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Old 09-12-16, 09:49 AM
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Instead of using a GMA-10A fuse..... use a GMA-7 or GMA-8.
 
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Old 09-12-16, 03:06 PM
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So I looked at some data sheets and think you guys are on to something. Using a 6amp fuse gives me around 10-30 seconds to interrupts at 10.3amps, and the Watters heater I am going to controlled is rated at 4.5 Amps max.

I will be plugging the whole thing into a 20a gfci outlet feed by a 20 amp breaker with 10awg wire. I planned to also have the actual switch I am controlling be gfci.

I am a huge believer in gfci I think my life was saved by one. I was placing a pump inside an aqarium as soon as I stuck the pump in the outlet tripped. I threw the pump away a day the outlet never tripped again.
 
 

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