AC voltage basics


  #1  
Old 08-17-05, 10:28 PM
johnp
Visiting Guest
Posts: n/a
Lightbulb AC voltage basics

I need a some basic refresher information on voltage levels. The voltage coming into ones house is 220 volts and that is split in half for most applications to 110 volts.?. Right?

Now where does the number 120 volts come from? Is this a maximum voltage level for correct operation?

In a perfect world, voltage would stay at a constant level, but it does vary at times. At what variances would it start causing problems? Does it matter on the sensitivity of the device being powered?

For example, I have an inverter that runs at 115 volts. It will run my portable fan no problem, but I tried to use an electrical blanket and it would not work.

Is my line of thinking correct? Help me out.

john
 
  #2  
Old 08-18-05, 04:24 AM
R
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,245
Upvotes: 0
Received 0 Upvotes on 0 Posts
The voltage coming into your house is nominally 240 volts, in two legs each of 120 volts. However, that voltage will vary. The further you are from the power company transformer, the lower the voltage, due to voltage drop. In practice the terms 110, 115 and 120 are used interchangeably, as are 220 230 and 240.

You generally do not have a problem unless the voltage varies considerable outside that range (like above 125). Whether a voltage problem will harm a device depends on a device. For example, an incandescent light bulb will work at lower voltages, it just will produce less light. it will also work at higher voltages, but if the voltage gets too high the light filament will burn out.

There is no perfect world. Sometimes the utility will lower the voltage that you receive. This is usually done in the summer when demand is highest. If the voltage is lowered, then there is more energy available for everyone.

Your electric blanket does not work with the inverter because the inverter cannot supply enough current to power it.
 
  #3  
Old 08-18-05, 08:21 AM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 9,785
Upvotes: 0
Received 45 Upvotes on 43 Posts
In the U.S., delivered voltage is considered normal between 110V and 127V. As racraft said, there are many factors that affect what voltage you actually get, but all appliances should operate safely within that range. It depends on the time of day, how far you are from the transformer, and your power company's policies as to what voltage you'll actually get. In my area, all of the utility companies provide 120V under normal conditions.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: