# Thread: 110v, 115v, 120v - Electricians and/or EE's Does it matter?

1. ## 110v, 115v, 120v - Electricians and/or EE's Does it matter?

I'm hoping someone can shed some light on "voltage" ratings for outlets, switches and appliances. I've read that for all practical considerations, that an outlet or switch rated at 110v 20 amp, versus 115v 20 amp, versus 120v 20 amp are equivalent. Such that if you install outlets that are rated 110v 20 amp, you are safe to use them to power motors spec'd at 120v 20 amp.

2. It's my understanding that all outlets are 120 volt or 240 volt and that 110 is just a laypersons number. You are definitely safe using a 120v 20 amp.

3. Technically, what is supposed to be at every outlet in your house is 120V. Once you take into account resistive losses, long line lengths, etc. it can vary a bit once it makes it to your house (particularly if you're far away from the main grid). You'll see mention of 110V, 115V, and so on, and many people may actually measure something similar at their wall, but it's designed to be 120V (and 240V when used across both phases, not the 210V, 220V, etc. you often see).

So, with that in mind, most things will work just fine on 110V, even if it was designed to run off of 120V. Electronics are downconverted to 12V, 5V, etc., so a little less at the high end is irrelevant. Motors, on the other hand, prefer to run at the voltage they were designed for. Running at a lower voltage increases the heat from the windings, so you want to watch the line from getting too low. Old refrigerators, well pumps, etc. can be victims of this. Newer equipment can often be controlled indirectly by microprocessors that handle variances in the line voltage, so they're somewhat safe to use on the lower voltages.

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105 ,110 ,115,120,125 volts do make a different when apply to a lamp bulb a high voltage will cause the bulb to be extra bright, the older transformer were rated for a lower voltage if I not mistaken

5. What Dan said...also depending on where you live voltage varies. If you live out in the sticks it is likely at the higher end.
I am not an electrician, but I play one from time to time...

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In a less than perfecxt world, ten per cent up or down should be okay on voltage. What I've been finding a lot of lately are cheap capaciters that just don't last. A capacitor not living up to it's rating can reak havoc, hot motor, burnout, etc.

7. 110V is a legacy term left over from ages gone by
115V comes from the design side, equipment is normally designed to run on 115V +/- 10%
120V comes from the supply side, under standard conditions electrical utilities deleiver electricity at 120V +/- 5%

In the end for us the numbers mean the same thing, just as 220/230/240 mean the same thing BUT 208V does NOT.

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Originally Posted by Nick Lazz
What Dan said...also depending on where you live voltage varies. If you live out in the sticks it is likely at the higher end.
I am not an electrician, but I play one from time to time...
Higher voltage is not just in remote areas. Where I live I can see the steam from exhausted neutrons at the Limerick nuke plant. The times I've checked line voltage - generally during hot spells with high air conditioning loads we run 124/248 volts. Just speculating here - no a sparky pro of any description - but I'm guessing they run as high as they can get by with to keep line & transformer temps down or capacity up? Higher volts require less amps to transport the same number of watts? We haven't had any electrical problems in the 16 years we've lived here so I'm not complaining.

9. My question was motivated by a discussion in another thread regarding remote control units for DC's. The OP asked about remote control units rated for 120v 20 amp. I suggested the iVac Pro which is rated at 115v 20 amp https://www.mbrightonline.com/ecomme...?ecategoryid=9.

The OP is concerned that since this module is not rated 120v 20 amp, it would not be up to snuff. My thought was that for this application the 115v 20 amp rating is essentially the same as a 120v 20 amp rating.

In many respects it is kind of a mute point as it relates to the OP, since the manufacturer now is stating that anyone running 1.5 HP or more should use a contactor in conjunction with the switch (use the switch to turn on the contactor). But still I thought it would be good to hear from those who understand this topic a little bit better about the appreciable difference between the ratings. I note that Leviton's 20 amp outlets are now rated at 125v.

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I forgot what my actual voltage are suppose to be but the multimeter read my voltage at 127 if I recall right, the electric company assume me that my voltage are okay

11. The voltage on commercial electrical power lines fluctuates, depending on the load. There are some loads--big motors, for example--that draw substantially more current when starting up than when running. Back in the early days of my career as a broadcast engineer, I worked at a high-power UHF TV station. When we fired up the big power supplies (the beam supplies for big klystron tubes), the fluorescent lights all over the building would go out for a fraction of a second.

The nominal voltage of electrical service--120/240 in the US--is the average voltage over time. Depending on whose set of standards you look at, the voltage could vary as much as +5% -13%. Properly designed electrical equipment is designed to deal with those variances. The NEMA (National Electrical Manufacturer's association) standard calls for electrical appliances and equipment to be designed to operate between -10% and +10% of nominal nameplate voltage. A motor with a nameplate rating of 115 volts is therefore designed to operate between 103.5 and 126.5 volts.

Bottom line: don't worry about it.

D.

12. Dan,

Those huge supplies are scary pieces of equipment. When I worked for a telecommunications consulting firm, the owner's son was out on a field call from a client with an AM tower. He didn't know the gate around the tower was there for a reason, so he put his hand out to lean on the tower. Needless to say, the spark that shot out of the tower did a bit of damage to his finger and made sure he never did that again.

13. Originally Posted by Dan Hintz
Dan,

Those huge supplies are scary pieces of equipment. When I worked for a telecommunications consulting firm, the owner's son was out on a field call from a client with an AM tower. He didn't know the gate around the tower was there for a reason, so he put his hand out to lean on the tower. Needless to say, the spark that shot out of the tower did a bit of damage to his finger and made sure he never did that again.
He was a lucky guy. RF energy burns from the inside out and the burns can be particularly painful. I've been bitten by a few AM's over the years. At lower power levels, it's seriously unpleasant. At higher power levels, it can be seriously life-shortening.

D.

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Joe, I think you have shown me the way! It appears the surge of my dust collector starting, as well as high amp output while running, causes the plug connection between my dust collector and the remote control unit to be welded together! (I am still awaiting receiving a amp meter to confirm my dust collector motor's output.)

It looks like the answer is to install a relay switch (contactor) between the dust collector and remote control. Yes, I know it is more expensive. It should solve my welding problem and having to replace remotes every so often.

Nice to see IVac has added a remote controller. I may want to go their components the whole way.

What does OP mean?

Originally Posted by Joe A Faulkner
My question was motivated by a discussion in another thread regarding remote control units for DC's. The OP asked about remote control units rated for 120v 20 amp. I suggested the iVac Pro which is rated at 115v 20 amp https://www.mbrightonline.com/ecomme...?ecategoryid=9.

The OP is concerned that since this module is not rated 120v 20 amp, it would not be up to snuff. My thought was that for this application the 115v 20 amp rating is essentially the same as a 120v 20 amp rating.

In many respects it is kind of a mute point as it relates to the OP, since the manufacturer now is stating that anyone running 1.5 HP or more should use a contactor in conjunction with the switch (use the switch to turn on the contactor). But still I thought it would be good to hear from those who understand this topic a little bit better about the appreciable difference between the ratings. I note that Leviton's 20 amp outlets are now rated at 125v.
Last edited by Bob Landel; 01-24-2012 at 12:34 AM.

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