NEC 210.6 A 120v limit for luminaire

[Jpflex]

If 120 volts is the limit between conductors supplying lighting systems for dwellings then if you obtain 126 rms volts or any voltage over 120 volts rms on your meter then this is a code violation?

What if utility has supply exceeding this by a small amount? Or transformer doesn’t have taps to step secondary voltage down further?

How do you redress this

 

[retirede]

The 120 is a nominal system voltage, not an absolute. I would expect ANSI standard tolerances (normally +-5%) to be acceptable, but I don’t have a code reference to back that up.

 

[infinity]

I don't see an issue. Read the IN:

Voltage, Nominal.
A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). (CMP-1)
Informational Note No. 1: The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.

 

[Jpflex]

The 120 is a nominal system voltage, not an absolute. I would expect ANSI standard tolerances (normally +-5%) to be acceptable, but I don’t have a code reference to back that up.

To this I would reference code mandating 5% voltage drop or less from the source to the outlet for equipment utilization or 3% drop from final over current device to outlet for utilization

 

[Jpflex]

I don't see an issue. Read the IN:

NEC is very good at contradictions in code. A limit should not mean a threshold

 

[Jpflex]

Or value over a “limit”

 

[don_resqcapt19]

To this I would reference code mandating 5% voltage drop or less from the source to the outlet for equipment utilization or 3% drop from final over current device to outlet for utilization

There is no general code rule on this in the NEC. The mandated voltage drops are in Article 695 and 647. The others are recommendations.

 

[tortuga]

210.6(A) and (B) are from days long by-gone .
If the circuits are protected in accordance with 210.12 or 210.8 you have nothing to be concerned about.
210.6(A) and (B) are way overdue for an update from 120 to 240 Nominal, and a update to 210.12 to reflect the change.

 

[don_resqcapt19]

The 120 is a nominal system voltage, not an absolute. I would expect ANSI standard tolerances (normally +-5%) to be acceptable, but I don’t have a code reference to back that up.

Not sure the code addresses that. The maximum and minimums are often set by the state public service commission. In Illinois the Commerece Commission sets the permitted range as 113 to 127 for a nominal 120 volt system.

 

[tortuga]

There is no general code rule on this in the NEC. The mandated voltage drops are in Article 695 and 647. The others are recommendations.

My understanding is most states now, including the states you all are from (and FL where Mike is based) have now mandated some form of voltage drop their energy conservation code, and its usually 5% total voltage drop total.
That FPN in the NEC is also overdue for an update it should direct the code user to check their local energy code for voltage drop rules.

Not sure the code addresses that. The maximum and minimums are often set by the state public service commission. In Illinois the Commerece Commission sets the permitted range as 113 to 127 for a nominal 120 volt system.

I agree you could have a 220Y127 transformer and that 127 would still be a 120V nominal system.

 

[don_resqcapt19]

My understanding is most states now, including the states you all are from (and FL where Mike is based) have now mandated some form of voltage drop their energy conservation code, and its usually 5% total voltage drop total.
That FPN in the NEC is also overdue for an update it should direct the code user to check their local energy code for voltage drop rules.


I agree you could have a 220Y127 transformer and that 127 would still be a 120V nominal system.

Yes, it is covered by the energy code, but that is not enforced around here.

As far as the nominal voltage, all I am saying is that for Illinois, the voltage range for a 120 volt nominal system is 113 to 127.

The supply from a 220y/127 volt system would be a 127 volt nominal system and I would not see it as a 120 volt nominal system.

 

[tortuga]

As far as the nominal voltage, all I am saying is that for Illinois, the voltage range for a 120 volt nominal system is 113 to 127.

The supply from a 220y/127 volt system would be a 127 volt nominal system and I would not see it as a 120 volt nominal system.

Yeah I could see 220Y/127 in a commercial / industrial building on a step down, if it was constantly supplied by a utility that would raise some eyebrows indeed.
220Y/127 is still 120V nominal in the sense that's its in ANSI C84 Table 1 range B
and you would not need a '127V' rated breaker or fuse.
The possible 10% over voltage range would be 140 so not over 150 Volts.
I draw the line at 225Y/130 (which would be a unicorn I have never seen).

 

[don_resqcapt19]

Yeah I could see 220Y/127 in a commercial / industrial building on a step down, if it was constantly supplied by a utility that would raise some eyebrows indeed.
220Y/127 is still 120V nominal in the sense that's its in ANSI C84 Table 1 range B
and you would not need a '127V' rated breaker or fuse.
The possible 10% over voltage range would be 140 so not over 150 Volts.
I draw the line at 225Y/130 (which would be a unicorn I have never seen).
View attachment 2564685

I would red tag any installation that had 120 volt rated equipment supplied from a 127 volt nominal system.

I have installed a number of 240Y/139 volt transformers, but they were used as drive isolation transformers for VFDs and the wye was only used to get a grounded system. No line to neutral loads.

 

[tortuga]

What is the safety hazard with calling such a 220Y127 system 120 nominal?
I would appeal based article 100 definition of 'Nominal' Informational Note No. 2