Multimeter reading hosehold power

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Old 04-23-10, 05:11 AM
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Multimeter reading hosehold power

Can someone please tell me what the reading should be when checking a house plug?Everything in my house is breaking and it is all electrical problems? i am trying to figure out whats going on?? I know standard is 120 but whats does it really read on a meter? my furnace is on its 2nd transformer in a week!!!
 
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Old 04-23-10, 07:57 AM
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It should read about 120VAC between the 2 flat prongs. Same between one of the prongs and ground (the oval hole). Should be 0 between the other prong and ground.

You may see SOME voltage when it should be 0...but thats called phantom voltage if you are using a digital meter. A meter with a needle should show 0.


EDIT...I oops there......it was still early.
 

Last edited by Gunguy45; 04-23-10 at 09:22 AM. Reason: Remove kinda wrong info
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Old 04-23-10, 09:13 AM
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If you are having electrical issues at the same time throughout the whole house you probably have an issue with the service neutral, which is one of wires that connects to your home from the power company.

Most power companies will come out and check this for free when you call their service number. Wind can cause the outdoor connections to come loose, and sometimes all they need to do is tighten a few lugs at the pole.

If you are measuring a standard 15A receptacle, the readings should be about:

narrow blade to wide blade: 110 - 125V
narrow blade to ground hole: 110 - 125V
wide blade to ground hole: close to 0V, certainly less than 5V

You will get more reliable measurements if you have a lamp plugged in to one side of the receptacle and turned on while you test the other side.

Do your lights flicker or get dimmer or brighter? Do you have an electric stove, water heater or dryer? Do you have electrical problems when any of those appliances are on?
 
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Old 04-23-10, 09:16 AM
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For the furnace problem, do you mean "just a transformer" is going bad or is there an "electronic circuit board" which is going bad?

Transformers like would be used for a doorbell are pretty sturdy typically. (old furnace only has this.)

Electronic circuit boards are subject to being wrecked by "voltage surges" (newer furnaces have these as well as a transformer.)

Then there is a transformer and along with it are electronic components (to make DC electricity). This is called a "power supply".

A voltage surge is a momentary "surge" of electricity and this will not typically damage a transformer. But will cause damage to electronic things. You would not be able to see this with a multimeter. If that is the problem, get a whole house surge protector and surge protection power strips at each outlet which has electronic things plugged in.

A different problem is a loose main "neutral" wire. This can cause 120 volt outlets to have near 240 volts! A multimeter would see this, but only when the problem is occurring. The solution to this is to have the electric company come out and "retorque" (tighten) the lug nuts on your main electrical wires. Tell them you think you have loose main electrical wire connections. Symptoms of this problem would be light bulbs getting very bright suddenly (because they are getting twice the electricity) or losing power to things or lights not working, then you turn something else on and the lights then work.

Transformer looks like this...
http://www.bcsideas.com/sc_images/pr..._001_image.jpg

Electronic circuit board looks like this...
http://www.dansdata.com/images/snapgear/pcb440.jpg

Power supply looks like this...
http://www.eeshops.com/images/XBOX-U...U-V1.0-1.6.jpg
 
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Old 04-23-10, 11:19 AM
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OK Let me get a little more into this and thanks for the reply's

here is what is going on...
First it was the microwave... randomly beeping.. no big deal thought it was garbage as it was just cheap n e ways now has stopped the random beeping and only works when it wants too.

2nd my washing machine... started off as coming ON when the furnace kicked on. This machine turns on when you first plug it in so it seemed like it was getting a drop in voltage when the furnace kicked on hence it was turning on??? and the same as the microwave it only works when it wants too now it will come on till the spin cycle then turn off or sometime will do the whole cycle with no problems and sometimes it won't come on at all?

Now my furnace the transformer last weekend this weekend the board in it (this is from the furnace repair man as it under warranty)

I did always notice and has been this way as long as i have owed the house that lights get BRIGHTER when my furnace is RUNNING but i never really thought much of this before.

2 weeks ago something popped in my in my surge protector i have my computer plugged into and made the room smell burned? yet everything still worked.i have replaced it with a newer one now?

i have also noticed my alarm clock will no longer hold time everytime i set it it ends up flashing 12:00 as in the power went out?!?!?

keep in mind ALL of this is within 2 months!

Hope this all made sense i just woke up and was in a rush to write it up !
 
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Old 04-23-10, 11:35 AM
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As Bill said....sounds like you need to call your power company. This is something they will do for free. They will check right up to the meter...anything after the meter is normally the homeowners problem.

You are the homeowner right? If not..get the landlord off his butt if the POCO finds nothing.

I'd seriously unplug anything you really value until this is fixed.
 
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Old 04-23-10, 12:07 PM
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Originally Posted by Helpmeoutplease View Post
lights get BRIGHTER when my furnace is RUNNING but i never really thought much of this before.
This is a classic symptom of a bad service neutral. First is to call the power company to have them check the connections outside the home. If they do not find the problem outside, you'll need to have an electrician check your meter base and main panel for damage to the service neutral.
 
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Old 04-23-10, 12:40 PM
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I agree with ibpooks. I would have the power company come out right away and get this checked out. When they come out try to have somewhat of a load on your system meaning, have your washer, some lights and other things on. Hopefully they will find something and will be a easy fix. Let us know the out come.

Jim
 
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Old 04-23-10, 12:42 PM
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OK power company is called..

But i actually had a new Smart meter installed on my house a couple weeks ago so i am thinking they might have seen if there was a problem there??

Thank god both my washer and furnace are newer and under warranty!

Anything else i can check or look into or any advise you can think of more I'll be listening!!
Thanks guys!
 
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Old 04-23-10, 12:48 PM
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No...the new meter is a direct replacement...unlikely they would check anything else. Like hoping the tire guy at WalMart notices your brakes are worn.
 
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Old 04-23-10, 02:41 PM
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THANK YOU THANK YOU THANK YOU GUYS!!!

Sure enough the power company came found a bad wire from the road to my house (looked all toasty in side) fingers crossed thats the only problem!

Agian thanks so much guys big weight of my shoulders!!
 
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Old 04-23-10, 06:29 PM
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Originally Posted by Helpmeoutplease View Post
Anything else i can check or look into or any advise you can think of more I'll be listening!!
You should have noticed such a problem long ago. If incandescent bulbs are changing intensity when washer, furnace, etc power cycle, then service should have been called back then.

Major appliances power cycling should not cause light bulb intensity changes. That change would have suggested a human safety problem existed.
 
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