Fused neutral

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GG

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Does the NEC prohibit a neutral from ever being fused or placed on a breaker? I realized the other day that strings of Xmas lights have 2 fuses in the plug, 1 on the hot and 1 on the neutral. I wonder why the need for 2 fuses instead of just the 1 on the hot wire?
 
GG said:
Does the NEC prohibit a neutral from ever being fused or placed on a breaker? I realized the other day that strings of Xmas lights have 2 fuses in the plug, 1 on the hot and 1 on the neutral. I wonder why the need for 2 fuses instead of just the 1 on the hot wire?
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cause it can be plugged in either way?
 
Fused neutral -- NOT

Fused neutral -- NOT

Christmas lights that are new enough to incorporate fuses in the plug would have a polarized plug. You see two fuses because one of them is a spare. It is nice having it stored in the plug instead of them being taped in a cheap plastic bag on the cord for them to get lost or thrown away.

Bill
 
GG said:
Does the NEC prohibit a neutral from ever being fused or placed on a breaker? I realized the other day that strings of Xmas lights have 2 fuses in the plug, 1 on the hot and 1 on the neutral. I wonder why the need for 2 fuses instead of just the 1 on the hot wire?
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Could one fuse be on the hot and the other just a spare fuse contained in the neutral side?
 
wdemos said:
Christmas lights that are new enough to incorporate fuses in the plug would have a polarized plug. You see two fuses because one of them is a spare. ...
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Ah - ha. Thankyou. As you can see, I am not a consumer electrical sort.

And generally need help - in that area as well as others. :)

cf
 
wdemos said:
Christmas lights that are new enough to incorporate fuses in the plug would have a polarized plug. You see two fuses because one of them is a spare. It is nice having it stored in the plug instead of them being taped in a cheap plastic bag on the cord for them to get lost or thrown away.

Bill
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I must respectfully disagree..I have seen many sets (none newer that a few years old though) where BOTH sides were indeed fused. I just bought a new C9 size set and will check it out to see, but IIRC the plug is NOT polarized.

I'm not sure the NEC has any specific prohibition on fusing the neutral in utilization equipment.
 
Our corner grounded delta services require a fused neutral

Our corner grounded delta services require a fused neutral

They require our 240V cormer grounded delta services to have a fused neutral. All the disconnects are required to be three pole with the neutral on the center leg.
 
mxslick said:
I must respectfully disagree..I have seen many sets (none newer that a few years old though) where BOTH sides were indeed fused. I just bought a new C9 size set and will check it out to see, but IIRC the plug is NOT polarized.

I'm not sure the NEC has any specific prohibition on fusing the neutral in utilization equipment.
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Just curious if that set was even listed as is now required.
 
Its an old system in downtown areas everywhere

Its an old system in downtown areas everywhere

The corner grounded delta comes into the distribution panel as three phase 240V. A to B =240: A to C = 240V; B to C is 240V . You can stick your tongue on the B Phase or the neutral but I advise against it. Its the neutral derived from the transformers. I guess it could be the ground down the B leg but from what I understand you pick your grounding up from earth . The AHJ requires 3 pole disconnects for this service. I may be overlooking something but Im pretty sure thats the way its installed. I suppose you could use single phase equipment and just make the panel look like a 240V Single phase panel, landing the B phase on the neutral bar, but they would not go for it.
 
aelectricalman said:
The AHJ requires 3 pole disconnects for this service. I may be overlooking something but Im pretty sure thats the way its installed.
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There's a difference between having a disconnect open all lines and having a fuse in the grounded conductor. A 3p breaker can be used because an overload on the grounded conductor will open all lines, but the same will not happen with three fuses.

Touching a grounded Delta conductor is no different from, or more dangerous than, touching a grounded neutral conductor. Still, we treat either one as an energized conductor past the point of system bonding, and for the same reasons.

It's also kinda funny how hard it is to see that a grounded conductor on a Delta is really the same as a grounded conductor on any other system. A neutral isn't any "safer" or "better" or "less insane" to ground than any other system conductor.

The only reason any supply conductor has a specific voltage to ground is because of the conductor that we intentionally ground. If we grounded one end of a 120/240v secondary instead of the center tap, we'd have one 120v and one 240v conductor.

The voltage between any pair of conductors will not change with a change of which conductor we ground; only the voltage to ground of each conductor will. Gounding basically creates an "earthly" extension of the grounded conductor.
 
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GG said:
I realized the other day that strings of Xmas lights have 2 fuses in the plug, 1 on the hot and 1 on the neutral. I wonder why the need for 2 fuses instead of just the 1 on the hot wire?
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Xmas lights not overed by the NEC as they aren't part of an installation.

I'm sure a code history expert will be along in a moment, but I'm sure I've read on this very forum that neutral fusing was banned in the early part of the 20th century, 1908 or 1930 is buzzing away in the head somewhere.....
 
iwire said:
In a round about way it tries to, the NEC requires holiday lights to be listed.

Now how that would be enforceable I have no idea.
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I will tell my wife she needs to get a permit before she put the lights on the tree she just bought. Then we will need a rough-in inspection and a final before she plugs them in. Then I can turn her in for doing electrical work with out a license. Lets see how far that will go;)
 
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