Can I protect wire with a fuse in main panel?

JoeNorm

Senior Member
I have to power a small low wattage electronic device. The device needs 240 volts. The main panel is full and I cannot make more space.

Is it legal to attach #14 wire to an existing 30 amp 2-pole breaker that powers the dryer and protect the #14 with inline fuses?

If the answer is yes, what type of fuse would I use?

Thanks
 

kwired

Electron manager
most the time the answer will probably be no. You are essentially installing an additional branch circuit, the OCPD needs to be a listed branch circuit device, you are using what is likely considered a supplemental protection device.
 

MAC702

Senior Member
Does your new device need overcurrent protection at the circuit breaker? Can you wire it with #10 and use the dryer breaker anyway?

...The main panel is full and I cannot make more space....
Not knowing your level of experience, any possibilities of tandem breakers?
 

hbiss

EC, Westchester, New York NEC: 2014
No, you can't do as you propose. And why are you picking on the dryer circuit anyway?

Choose two adjacent 15A breakers, install a handle tie and pigtail the existing circuits and your new circuit off of them.

-Hal
 

synchro

Senior Member
No, you can't do as you propose. And why are you picking on the dryer circuit anyway?

Choose two adjacent 15A breakers, install a handle tie and pigtail the existing circuits and your new circuit off of them.

-Hal
Good idea.
Also, for the OP these two single-pole 15A breakers should not be GFCI or they will trip with any line current that does not return though the breaker's neutral connection.
 

growler

Senior Member
Is it legal to attach #14 wire to an existing 30 amp 2-pole breaker that powers the dryer and protect the #14 with inline fuses?
Ever hear of a "Quad" breaker ? You should be able to get a double pole 30 and a double 15 amp into a regular size two pole breaker space.

A quad is like a tandem for double pole breakers.
 

JoeNorm

Senior Member
Thank you for the responses. Yes I do know what a quad is but I cannot get one for a couple days in my area.

All the 15 amp circuits are already on tandems and this device does not warrant the expense of a sub panel. One thought is to tie the handles of two of the twins next to one another. Not sure if they make a tie for that.

thanks again. At least I know fuses are out of the question.
 

kwired

Electron manager
Thank you for the responses. Yes I do know what a quad is but I cannot get one for a couple days in my area.

All the 15 amp circuits are already on tandems and this device does not warrant the expense of a sub panel. One thought is to tie the handles of two of the twins next to one another. Not sure if they make a tie for that.

thanks again. At least I know fuses are out of the question.
Can't tell you about others, but pretty sure Square D does for QO and likely for Homeline as well.
 

JoeNorm

Senior Member
Can someone point to an article in the NEC that makes it clear that fuses cannot be used for this purpose? I believe you all, but I have others telling me it'd be legal to install a fuse. I'd like to be able to point to the article to settle it.
 

charlie b

Moderator
Staff member
I think that all you need is 110.3(B). The installation you described would take the panel beyond the manufacturer's listing.
 

Jraef

Moderator
Staff member
Aside from that, you are not likely to find a 30A 2P breaker that is rated for more than one conductor per terminal. QO breakers are rated for 2 per terminal, but only up to 20A I believe. And even if you find something rated for two terminals, most likely they will have to both be #10s, not a #10 and a #14. So whoever is telling you this is OK is not giving you sound advice.
 

Russs57

Senior Member
It might help if we knew what the device was, wattage needed, and where it will be located.

For example, can you plug a 120 X 240 transformer/SMPS into a wall outlet and power this device. Maybe something made to allow use of UK devices in the states? Shouldn't cost much.

Just trying to come up with alternatives.
 

sameguy

Senior Member
Cost?
$60 for sub
Time you spent trying to save money costs money. Sooo your kind of falling behind in profits right now.
 

growler

Senior Member
It might help if we knew what the device was, wattage needed, and where it will be located.

For example, can you plug a 120 X 240 transformer/SMPS into a wall outlet and power this device. Maybe something made to allow use of UK devices in the states? Shouldn't cost much..
You know I was kind of wondering about that myself. The OP said it a low wattage electronic device. Electronic devices may have an input voltage of 120V or 240V but that's not what they use. They normally have a transformer that steps it down to 12V AC and then it goes into a power supply and is converted to DC.

There could be all kinds of options if you only knew what you were dealing with.
 

hbiss

EC, Westchester, New York NEC: 2014
Can someone point to an article in the NEC that makes it clear that fuses cannot be used for this purpose? I believe you all, but I have others telling me it'd be legal to install a fuse. I'd like to be able to point to the article to settle it.
The Code can't address every situation specifically. So don't look for an article that says JoeNorm shall not install a fuse in any panel. I too think 110.3(B) covers it by saying that if you really want to know, ask the manufacturer if the listing would allow a fuse and fuseholder within the panel interior.

You know what the answer will be.

-Hal
 

kwired

Electron manager
Aside from that, you are not likely to find a 30A 2P breaker that is rated for more than one conductor per terminal. QO breakers are rated for 2 per terminal, but only up to 20A I believe. And even if you find something rated for two terminals, most likely they will have to both be #10s, not a #10 and a #14. So whoever is telling you this is OK is not giving you sound advice.
QO, Homeline, even NF and I line breakers accept two conductors up to 30 amp devices.
 

kwired

Electron manager
The Code can't address every situation specifically. So don't look for an article that says JoeNorm shall not install a fuse in any panel. I too think 110.3(B) covers it by saying that if you really want to know, ask the manufacturer if the listing would allow a fuse and fuseholder within the panel interior.

You know what the answer will be.

-Hal
The panel is the assembly inside the "cabinet" that contains bus bars and overcurrent devices. I really doubt the manufacturer instructions specifically address this as panelboards are one code section and cabinets are another.

A "loadcenter" is not a code term, it is a factory assembled cabinet with panelboard for the most part, though they are still two separate items to NEC. Cover may be included or may be an item with options and sold separately.
 
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