Should I upsize the wire on a 250ft run?

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infinity said:
75 posts and over a simple subject. :rolleyes:

The NEC doesn't care about voltage drop for this feeder, it's a design issue. If the installer wants to consider the voltage drop he can use the actual load or the size of the OCPD ahead of the feeder or some number in between. Any of those methods is code complaint.
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I agree. The heater just puts out a little less heat because of voltage drop. Depending on where the feed is run, might not really be totally lost heat in the lines though. Heater not likely running during cooling season so not a problem at that time of year.

Welder and plasma cutter probably can handle fair amount of voltage drop without much impact on performance - will draw more current to compensate though. Also kind of equipment that if the weld isn't hot enough, user turns the heat up anyway.
 
mbrooke said:
Assuming the voltage stays constant at the transformer during the fault. IEC-61200-413 goes into technical detail behind 5 seconds vs 0.8 seconds mandated in IEC-60364-4-41. I will post screen shots if you want them.
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As long as NEC table 310.16 allows 100 Amp loads on #3cu from 75°C table column; and all equip. is listed for => 75° C, no other derating factors, nameplate, continuous or inductive adjustments are required, then inspectors don't red tag a 100A OCP, much less 2% voltage drop.

However, if plans were required and include fault current considerations, using either IEC GEMI, or other engineering supervision, then inspectors can enforce those plans, and installers are more cooperative.
 
ramsy said:
As long as NEC table 310.16 allows 100 Amp loads on #3cu from 75°C table column; and all equip. is listed for => 75° C, no other derating factors, nameplate, continuous or inductive adjustments are required, then inspectors don't red tag a 100A OCP, much less 2% voltage drop.

However, if plans were required and include fault current considerations, using either IEC GEMI, or other engineering supervision, then inspectors can enforce those plans, and installers are more cooperative.
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One could debate if an inspector could enforce "effective ground fault current path"...
 
mbrooke said:
Link the specific text which says that. It makes it very clear what the code is trying to accomplish.
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(C) Relation to Other International Standards. The requirements
in this Code address the fundamental principles of
protection for safety contained in Section 131 of International
Electrotechnical Commission Standard 60364-1, Electrical Installations
of Buildings.
Informational Note: IEC 60364-1, Section 131, contains fundamental
principles of protection for safety that encompass protection
against electric shock, protection against thermal effects,
protection against overcurrent, protection against fault currents,
and protection against overvoltage. All of these potential
hazards are addressed by the requirements in this Code.
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This is what it says.

Note that it never says the IEC standard is incorporated. The informational note goes farther and makes it clear that the NEC addresses the same hazards as the IEC standard, but never comes even close to incorporating that standard.
 
petersonra said:
This is what it says.

Note that it never says the IEC standard is incorporated. The informational note goes farther and makes it clear that the NEC addresses the same hazards as the IEC standard, but never comes even close to incorporating that standard.
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"Relation to"
 
mbrooke said:
One could debate if an inspector could enforce "effective ground fault current path"...
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Informational notes themselves are not considered an enforceable part of the NFPA-70 standard.

Without any engineering plans or "assured grounding and bonding" policy to enforce, inspectors cite 250.118 for type of EGC, 250.120 for install methods, and 250.122 for proper EGC size.

Since only equipment damage is considered in 110.10 Circuit Impedance, Short-Circuit Current Ratings, and Other Characteristics. or GFPE @ 30mA elsewhere for feeders, NEC 2017 Art.230.95 may be the first requirement agaist hazardous fault current touch potential for personel.
 
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ramsy said:
Informational notes themselves are not considered an enforceable part of the NFPA-70 standard.
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Sure, not dispute here.

Without any engineering plans or "assured grounding and bonding" policy to enforce, inspectors cite 250.118 for type of EGC, 250.120 for install methods, and 250.122 for proper EGC size.
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How does that make 250.4 (A) 5 optional or none enforceable?


Since only equipment damage is considered in 110.10 Circuit Impedance, Short-Circuit Current Ratings, and Other Characteristics. or GFPE @ 30mA elsewhere for feeders, NEC 2017 Art.230.95 may be the first requirement agaist hazardous fault current touch potential for personel.
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At one point in history it was the the first line of defense. That is until you consider the code technically does not want you plugging loads of equipment into a GFCI without an equipment ground. 250.114.
 
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ramsy said:
Since only equipment damage is considered in 110.10 Circuit Impedance, Short-Circuit Current Ratings, and Other Characteristics. or GFPE @ 30mA elsewhere for feeders, NEC 2017 Art.230.95 may be the first requirement agaist hazardous fault current touch potential for personel.
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Here is 406.4 D 2 C:

1613079357637.png

Informational note two while not enforceable in of itself sends you to 250.114 where neither 406.4 nor 250.114 appear to have a clause or exception for the appliances listed in 250.114 for when an ungrounded GFCI is present.

This would give insight that an effective ground fault current path is the primary means by which protection against electrocution is achieved and not ground fault circuit interrupters which are essentially a back-up.

Further consider that a fault on the building's wiring will not trip a receptacle GFCI unless said wiring is feeding through the GFCI.
 
mbrooke said:
How does that make 250.4(A)(5) optional or none enforceable?
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If AHJ inspector interprets "low impedance" as engaging the instantaneous trip function, rather than over current function, and produces a calculation to prove deficiency, it may be enforceable. Especially where no challenge is attempted.
 
ramsy said:
If AHJ inspector interprets "low impedance" as engaging the instantaneous trip function, rather than over current function, and produces a calculation to prove deficiency, it may be enforceable. Especially where no challenge is attempted.
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Right, so in such a cases circuit breaker size and/or circuit size would matter.

Larger wire means more fault current. Lower rated breaker mean a lower current pickup.
 
mbrooke said:
..neither 406.4 nor 250.114 appear to have a clause or exception for the appliances listed in 250.114 for when an ungrounded GFCI is present.
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Roger that. Inspectors can red tag 3-prong appliance cords plugged into such GFCI protected outlets missing EGC wiring.

However, there is always exceptions in the National Exceptions Code (NEC).

250.114 Exception: Listed tools, listed appliances, and listed equipment covered in 250.114(2) through (4) shall not be required to be connected to an equipment grounding conductor where protected by a system of double insulation or its equivalent. Double insulated equipment shall be distinctively marked.

That leaves 1 place 3-prong is mandated:
(1) In hazardous (classified) locations (see Articles 500 through 517)]
 
ramsy said:
Roger that. Inspectors can red tag 3-prong appliance cords plugged into such GFCI protected outlets missing EGC wiring.

However, there is always exceptions in the National Exceptions Code (NEC).

250.114 Exception: Listed tools, listed appliances, and listed equipment covered in 250.114(2) through (4) shall not be required to be connected to an equipment grounding conductor where protected by a system of double insulation or its equivalent. Double insulated equipment shall be distinctively marked.

That leaves 1 place 3-prong is mandated:
(1) In hazardous (classified) locations (see Articles 500 through 517)]
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If double insulated.
 
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