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-   -   Is this proper? (Garage switch) (http://www.diychatroom.com/f18/proper-garage-switch-98699/)

twinrider1 03-17-2011 02:34 PM

Is this proper? (Garage switch)
 
I want to put 220 in my garage so I've been looking at what I have currently.

When I looked at it, it made me wonder if it was safe in it's current
In the garage now is a Crouse-Hinds GP321N.
It is rated for 30 amps. Is that 30 amps per pole or a total for both poles?
I ask because right now it has two 20 amp fuses. Is that proper?

This isn't mine, but it's the same model.
http://i90.photobucket.com/albums/k2...ric/GP321N.jpg

Thanks,
Mike

HouseHelper 03-17-2011 03:11 PM

That would be 30A per leg.

Saturday Cowboy 03-17-2011 05:57 PM

30a@240v Total sorry there is no way to get sixty amps out of a 30a

joed 03-17-2011 07:47 PM

Just because it is rated for 30 amps doesn't mean you can put 30 amp fuses in it. 30 amps is the max rating. If it is feeding #12 wire then 20 amps is the proper fuse.

twinrider1 03-17-2011 07:52 PM

Maybe I'm mixing together two different questions. (Or I'm trying to combine the two answers. :-))
The box itself, let's say it's in a new installation. It's lists a max of 30amps. That's a max for the box, not each pole? So it could be 15 amps per pole.......two 15amp/120volt circuits (one per pole) or one 30amp/240volt (both poles running as one circuit).

Hope that helps instead of clustering it further.

(EDIT: Was typing as joed posted)

Wildie 03-17-2011 08:39 PM

Quote:

Originally Posted by joed (Post 611568)
Just because it is rated for 30 amps doesn't mean you can put 30 amp fuses in it. 30 amps is the max rating. If it is feeding #12 wire then 20 amps is the proper fuse.

I've been putting 30 amp fuses in 30 amp disconnects for 30 years.
R U saying that i've been doing this wrong, all my life? :eek:

Saturday Cowboy 03-17-2011 09:05 PM

remember that OCPD is determined by wire size

joed 03-17-2011 09:15 PM

Quote:

Originally Posted by Wildie (Post 611597)
I've been putting 30 amp fuses in 30 amp disconnects for 30 years.
R U saying that i've been doing this wrong, all my life? :eek:

It depends on the wire attached to the fuses. I mention 20 amp because of this statement.
Quote:

I ask because right now it has two 20 amp fuses. Is that proper?

twinrider1 03-17-2011 09:32 PM

The idea being the fuse is there to protect the wiring.

Backtracking a bit then, narrowing it down to the box itself. When it says 30amp max, does that mean it can handle 30 amps on each pole?

joed 03-17-2011 10:54 PM

Yes, 30 amps each pole.

nap 03-17-2011 10:57 PM

ok, a 30 amp rated disco means you can run up to 30 amps through it.

You cannot (legally) use a fuse over 30 amp size

You can put any size fuse smaller than that that will fit.

as another said; fuse size and conductor size are complementary to each other. You cannot use a fuse larger than the wire is rated for.



you do not add the 2 poles together to get the max available amperage. It 30 amps per pole. If you use it as a 240 volt circuit, you get 30 amps at 240 volts. If you use it to feed 120 volt circuits, you can get 2 30 amp 120 volt circuits out of it. You cannot get 1 60 amp 120 volt circuit from this.

twinrider1 03-18-2011 12:22 AM

Ok, I get it now. In my head I kept thinking I had to divide the 30amps between the poles. I'm comfortable with DC systems, but I don't have much experience with AC circuits. It's a different way of thinking about things.

Ok, next step will be to see what size wire is running to the switch.

joed 03-18-2011 08:31 AM

The switch fuses protect the wire running FROM the switch, not TO the switch. The wire running TO the switch should be protected by a fuse or breaker in the panel supplying the power to this switch.

SD515 03-18-2011 10:32 AM

Quote:

Originally Posted by twinrider1 (Post 611717)
...I'm comfortable with DC systems, but I don't have much experience with AC circuits. It's a different way of thinking about things...

Not really for the most part. I'm constantly converting an AC circuit to DC in my head...for installations, troubleshooting, etc. Power comes in, goes through devices, goes back out to source. Same as DC. Physical materials & hookup may be different, but it's the same principle (basically, with exceptions).

nap 03-18-2011 12:50 PM

Quote:

Originally Posted by SD515 (Post 611873)
Same as DC. Physical materials & hookup may be different, but it's the same principle (basically, with exceptions).

So, it is as one of my brother's teachers used to say:


It's the same only different.:laughing:


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