How low is low?

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tonype

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At a recent home inspection, all 120-volt receptacles generally tested in the 110.1 (lowest one I found) to about 115 volts. It is my understanding that this is within the +/- 10% of 120 and would be considered OK; however, are there concerns with this? The service and main panel are relatively new and appeared in good condition (interior wiring is a mix of late 1960's and 2000's). Could it be a function of where the home is located - the home is on street where there is no outlet - several more blocks of homes after are present, but no way out? .
 
If there is no difference between the voltage at the service and the voltage at the receptacles I see no cause for concern. Did you check incoming voltage?
 
most likely the house is in an area that poco simply is bit low. Chances are if you take the reading when demands are low ,like maybe 3 AM that it will go up a few volts. Your test proves very little without knowing the voltage at the main service. Now if your finding 120 volts at the service and 115 at the receptacle then i would be concerned. Also your readings should be with a small load on them.
 
Jim W in Tampa said:
most likely the house is in an area that poco simply is bit low. Chances are if you take the reading when demands are low ,like maybe 3 AM that it will go up a few volts. Your test proves very little without knowing the voltage at the main service. Now if your finding 120 volts at the service and 115 at the receptacle then i would be concerned. Also your readings should be with a small load on them.
Click to expand...

Jim:

My thoughts were like yours - the home is near the end of the line. In addition, yesterday, despite the 10:30 AM time that I was there, was already hot and humid - many a/c's were in operation.

In the future, is there a safe way (as a non licensed electrical contractor) to take a reading at the service?

For receptacles, I use a "Sure Test" circuit analyzer - does not provide any load (that I am aware of) - just plugs in and gives the for me to the line voltage.
 
tonype said:
In the future, is there a safe way (as a non licensed electrical contractor) to take a reading at the service?

For receptacles, I use a "Sure Test" circuit analyzer - does not provide any load (that I am aware of) - just plugs in and gives the for me to the line voltage.
Click to expand...
I pretend to be an engineer, not an electrician, but roles overlap in commissioning jobs. I respect your not opening energized panels.

If there is no load on the circuit, the voltage you read will be the service voltage. You likely can use a laundry receptacle for one side reliably. To KNOW one on the other side of the 120-0-120 is harder; I'm not certain that all panels orient breakers that an adjacent and opposite breakers are on the other "phase". Often, the manufacturer's panel layout is available without doing any more than opening the door.
 
tonype said:
Jim:

My thoughts were like yours - the home is near the end of the line. In addition, yesterday, despite the 10:30 AM time that I was there, was already hot and humid - many a/c's were in operation.

In the future, is there a safe way (as a non licensed electrical contractor) to take a reading at the service?

For receptacles, I use a "Sure Test" circuit analyzer - does not provide any load (that I am aware of) - just plugs in and gives the for me to the line voltage.
Click to expand...

Without opening a panel you could check voltage at the dryer or range receptacles. Being it will have no load you will get a somewhat correct reading. Are some cases where what is at poco side and this location could change ,such as a long run from meter to the panel or a sub panel.
But without opening the panel you will not see many things of importance like wrong size breaker and wires or 2 circuits landed under 1 lug (on some brands ok). How far you go with inspections depend on your qualifications. Low voltage to a degree of too low is not likely.
There are many problems such as 3 prong outlets that have no grounding conductor or rigged to lie to your tester. Best advice to a HI is work in the field a few years first.
 
If you remember the voltage was:
110v/220v
115v/230v
120v/240v
Depending on what the power co. is giving mine is 118v.
It all works.
 
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