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#187496 - 06/28/09 08:29 PM Which Cartridge Fuse?
thiggy Offline
Member

Registered: 05/12/04
Posts: 25
Loc: B'ham Al
I have an old family farm house with a 125 amp Square D breaker box. The service disconnect is a 100 amp Square D cartridge fuse. I have never had the main blow, but I decided that I better have a spare pair of fuses on hand just in case, as in this rural area it would be difficult to locate one in a hurry. I drove to the nearest city and located fuses at Lowes, but I am not sure which one of the two types they had should be used for my application. The heavy-duty time-delay one said it is "for motor and main panel protection. (FRN-R)" It indicated that "for lighting or electric heating circuits use general purpose fuses.(NON)" I use window AC units for cooling, and 1500 watt portable heaters for infrequent use in winter heating. Water heaters are also electric. (This is generally just a week-end house.) Which type of fuse would be the most appropriate for my use?

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#187497 - 06/28/09 10:41 PM Re: Which Cartridge Fuse? [Re: thiggy]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
I would go with the FRN.
That will tolerate a short time spike in current.
The biggest opportunity for a spike in current is when you have a power glitch and the service would see locked rotor from every motor that was running at that time.
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#187499 - 06/29/09 01:28 AM Re: Which Cartridge Fuse? [Re: gfretwell]
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8530
Loc: SI,New Zealand
Yeah,
I agree with Greg.
You really need something with a bit of time delay on it for a main fuse.
After all, the fuse/CB that is electrically closest to the fault (ie, a sub-circuit fuse/CB) should operate first, in any electrical system.
Anything less is poor design.
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#187503 - 06/29/09 09:19 AM Re: Which Cartridge Fuse? [Re: Trumpy]
electure Offline

Member

Registered: 12/24/00
Posts: 4225
Loc: Fullerton, CA USA
You answered your own question.

Quote:
The heavy-duty time-delay one said it is "for motor and main panel protection. (FRN-R)"

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#187509 - 06/29/09 10:09 AM Re: Which Cartridge Fuse? [Re: Trumpy]
thiggy Offline
Member

Registered: 05/12/04
Posts: 25
Loc: B'ham Al
Thanks for the responses. I shall go with the time delay fuse. (I actually bought two of both types with the intention of returning one pair after I determined which type I should use.)

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#187517 - 06/29/09 05:24 PM Re: Which Cartridge Fuse? [Re: thiggy]
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
There is almost no reason to ever install an NON fuse. For all intents NONs are old technology, and are almost always sold based on price only.

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#187526 - 06/29/09 08:36 PM Re: Which Cartridge Fuse? [Re: JBD]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
We used NONs to protect electronics and there was even a faster blowing fuse that we used for the input to switcher power supplies way back when they were a big cabinet full very expensive parts.
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