Plug fuses in a disconnect switch box wired for 240v : aka Teach me about Plug Fuses

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hudstr

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I bought and wired up this 30 amp 2-pole fused disconnect box. It is advertised as "Single Phase 120/240". I have it wired up with 2 hots coming into the line at the top, then the two loads out for 240v for the rotary phase converter that came with the lathe. Unfortunately for me, it seems plug fuses are only rated to 125v and 250v ones don't exist because I can't find them anywhere. I am starting to think the design of the fuse socket itself is the limiting factor for voltage rating so it doesn't arc. I don't need the fused functionality, there is already a 30amp breaker.

Am I crazy or is it just not possible to get 240v out because 250v plug fuses don't exist. Are dummy plug fuses a "solid" connector meaning current will flow or are they an insulator to disable the circuit and fill the fuse socket? The eaton catalog still only lists the dummy fuse under 125v. Is there any proper way to fix this or do I need to start over with a different box?
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You use the standard fuse. The two hot lines only have 120 volts on each. These are the same fuses that you will find in an electric stove.
 
The whole box is only rated for two 120 volt circuits. It's 240 in, and a pair of 120's coming out.

L is light duty.
2 is two poles.
1 is 120 volts
1 is 30 amps
N is factory installed neutral.

If you can get your hands on an L221N you could make that work.

Straight out of the papers that came with the L221N that lives in my junk pile until I can find an excuse to use it or throw it away. Pro tip- If you're looking for specs on electrical shenanigans, go STRAIGHT to the manufacturer. They've all got great information on their websites. Store websites, maybe not so much so. Most places "show" those little screw in fuse holders as "240 volt", which is not "wrong"... It's input is 240 volt, but it's output can not be.
 
You really should have just bought a non-fused disconnect but you can find glass fuses for it in many hardware stores and on Ebay
 
Hey, two posts in while I was digging out the papers....

You ABSOLUTELY NEED to have a 240 volt rating on the fuses on this circuit if you're sending 240 volts out of that box. They are NOT separate legs in this case, and they ARE presented with a 240 volt potential in the event of a fault.

Go to the manufacturer's web site, dig up the product sheet. Don't take electrical advice from myself or anyone else on the internet.
 
MrWhoopee said:
I believe pennies are rated for 250v. ;)
Click to expand...

You might be right. Provided that they were both 'pennied', that would never allow the underrated plug in fuse to open the circuit (which the OP has stated is protected upstream). That is where the problem lies. The amps are fine, but when the plug fuse blows, it's not rated to blow "open enough" to guarantee zero current flow at the voltage in question. That would still allow the load side of that box to see double it's current rating, but the enclosure is rated for fire, not volts... I wonder which side the switchgear is on?

I'd still use something rated for more than half the voltage. If it's "breakered" properly wherever this circuit originates, and all the wiring adequate, a non-fused switch might suffice. Certainly it would suffice as well as butchering the fused switch in question, but it wouldn't leave lingering questions. I don't think we've heard what the purpose of this . Is it required?
 
Thanks for the responses everyone. I should have explained better what I am trying to do. I am trying to power a rotary phase converter and maybe add a 240v outlet for a welder.
wiring_diagram.jpg
For the rpc, all I need to do is connect the two lines coming into the house to L1 and L2 respectively, right? There is no manufacturer sticker, only the wiring diagram inside the little junction box on it.
IMG_20220829_202013076.jpg

I wanted a disconnect box on the wall so I would be able to disconnect the entire machine. I am reusing wire that used to go to a stove that was moved and wired with a new circuit. I figured the box with lugs would make it easy to connect the 6 gauge aluminum wire(the box specs say 8 gauge max but it fit and torqued so I should probably change it for that reason alone). I don't believe I need the fused capability, I just bought something off the shelf I thought would work because I am stupid.



This is the wiring diagram from the manufacturer for the box L211N.
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I get that each hot is 120v when referenced to neutral/ground. I get confused about the voltage the fuses need to be rated to in this configuration.
 
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I wonder which side the switchgear is on?
Click to expand...
I'm not 100% if that means what I think it means but the "order" if that is what you'd call it goes Line In->Switch->Fuse->Load
 
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