Where did 118v AC rating come from? Old GE ballast

[Electric-Light]

Back in the days when the frequency was referenced as "cycles" rather than Hz, some loads were rated 118v. Where did this come from?

Someone said voltage was officially 230 before it became 240 somewhere. Is there something to be said about 118v too?

 

[sameguy]

110v/220v, 115v/230v, 120v/240v, 118v falls between 115v and 120v I would think G.E. was giving a target voltage for what was around then.

 

[Jraef]

+-10% gave it an acceptable range of 106V to 130V. In the early days of power generation and distribution, each power utility had their own specs, so there were many different voltages being sent around at the local user level. There was no "grid" so to speak. So mfrs of equipment had to cover the gamut of what the end user may have available: 110V, 115V, 120V, 125V, 130V etc. So 117 and 118V were at one time a common compromise. But now, most of the 125V and 130V systems have gone away, so you see 115V as the common compromise voltage level.

 

[Electric-Light]

so you see 115V as the common compromise voltage level.

I know that induction motors are always 115, 230, 265, 460 but everything else I see around are 120v only.

 

[broadgage]

I have seen ratings of both 117 and 118 volts on old USA ballasts.
I had allways presumed that this was the estimated actual average voltage at the point of use, with a nominal 120 volts at the service.
Although the NEC does not specify the allowable voltage drop in an installation, 3% is very widely accepted as good practice or a rule of thumb.
If an installation is designed for a maximum voltage drop of 3%, then the average drop will be less than 3% (lamps part way along a circuit, not all lamps lit, shorter branch circuits etc) That would suggest an actual voltage at the fixture averaging 117/118.

 

[LarryFine]

I've seen 110, 112, 115, 118, and 120v, plus 125v for equipment.

 

[cadpoint]

...so you see 115V as the common compromise voltage level.

If your reference is to the set level, I'll say your low, if your saying a Mean level, I'll also say your low. My POCO has been runing on the high side of 120+ for years.

Maybe it's just me ... Amped...