New circuit in old fuse panel?

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Coppersmith

Coppersmith

Senior Member
Location
Tampa, FL, USA
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Electrical Contractor
Is there any code rule preventing me from adding a new 240v circuit to a fuse panel?

if not, does the 240v circuit have to go on one of the pullouts with two cartridge fuses or can it be on two screw-in fuses?

As an alternative, can I add a subpanel fed by the fuse panel?

(Yes, I know they should replace it.)
 
Coppersmith said:
Is there any code rule preventing me from adding a new 240v circuit to a fuse panel?

if not, does the 240v circuit have to go on one of the pullouts with two cartridge fuses or can it be on two screw-in fuses?

As an alternative, can I add a subpanel fed by the fuse panel?

(Yes, I know they should replace it.)
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240.40 doesn't clearly state it, but sort of seems to indicate you must disconnect all conductors of the circuit ahead of the fusholders, pullout style would fulfill this.

240.50 doesn't allow plug fuses to be used on circuits over 125 volts between conductors. Don't know how long that has been a requirement as I have seen many old installs with plug fuses on 240 volt circuits.
 
Imo, you cannot use 2 screw fuses for a 240 volt circuit.


240.40 Disconnecting Means for Fuses. Cartridge fuses in
circuits of any voltage where accessible to other than qualified
persons, and all fuses in circuits over 150 volts to ground, shall
be provided with a disconnecting means on their supply side so
that each circuit containing fuses can be independently disconnected
from the source of power. A current-limiting device
without a disconnecting means shall be permitted on the
supply side of the service disconnecting means as permitted by
230.82. A single disconnecting means shall be permitted on the
supply side of more than one set of fuses as permitted by
430.112, Exception, for group operation of motors and
424.22(C) for fixed electric space-heating equipment.
Click to expand...
 
kwired said:
240.50 doesn't allow plug fuses to be used on circuits over 125 volts between conductors. Don't know how long that has been a requirement as I have seen many old installs with plug fuses on 240 volt circuits.
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But what about a 240v 2 pole fused safety switch? In that case there is a switch ahead of the fuses and in later models a door interlock when in the ON position. I have one on my shop compressor circa 2001 but come to think of it I have not seen plug fuse safety switches available in recent years. Was this a code change?
 
Andy Delle said:
But what about a 240v 2 pole fused safety switch? In that case there is a switch ahead of the fuses and in later models a door interlock when in the ON position. I have one on my shop compressor circa 2001 but come to think of it I have not seen plug fuse safety switches available in recent years. Was this a code change?
Click to expand...

I never realized this until replying to this thread but:

240.50 General.
(A) Maximum Voltage.


Plug fuses shall be permitted to be used in the following circuits:


(1) Circuits not exceeding 125 volts between conductors
(2) Circuits supplied by a system having a grounded neutral point where the line-to-neutral voltage does not exceed 150 volts
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Sure looks to me like as it is worded you can not use plug fuses for a straight 240 volt branch circuit.

A multiwire branch circuit, maybe? A two pole fused disconnect with plug fuse holders would be somewhat useless if you can't even use them for multiwire branch circuits, but you still have over 125 volts between two conductors in a MWBC so as is written I think you could only supply two separate 120 volt circuits from such a switch - to be code compliant.
 
kwired said:
I never realized this until replying to this thread but:



Sure looks to me like as it is worded you can not use plug fuses for a straight 240 volt branch circuit.

A multiwire branch circuit, maybe? A two pole fused disconnect with plug fuse holders would be somewhat useless if you can't even use them for multiwire branch circuits, but you still have over 125 volts between two conductors in a MWBC so as is written I think you could only supply two separate 120 volt circuits from such a switch - to be code compliant.
Click to expand...

Well, I did not know that. So I could not use this for a 240V disco? I wonder why?


View attachment 18390
 
jumper said:
Well, I did not know that. So I could not use this for a 240V disco? I wonder why?


View attachment 18390
Click to expand...
Tried to blow page up so I could read the label, but was too hard to read.

Looked into catgalog info though - the Cat # D211N denotes:
D - General duty
2 - 2 poles
1 - 120 VAC voltage rating
1 - 30 amp rating
N - factory installed neutral

But yet Hp ratings table says that switch is rated 1.5 HP standard and 3 HP max at 240 volts:huh:
 
Well isn't there now something in the 2014 NEC about handle tying breakers feeding MWBC? If this is the case than plug fuses would certainly violate this unless as a pull block. Now the above switch should be OK as it breaks both hots at once? And it isolates the fuse holder when off.

And consider too that fused MWBC or even fused 240v such as a water pump or pool filter will be a legacy installation and thus grandfathered?
 
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