utility company voltage tolerance

[g-and-h_electric]

I am on vacation (which I really needed!). Just got a call from one of our commercial guys, he has 201 V at a pump on a 3p 120/208 Y service and thinks that is too low. The pump is running, and I am curious what the accepted tolerance from the power company usually is. I thought the low rnd was about 197, but I could be wrong....

 

[Elect117]

10% to 5% depending on the utility. They usually put their standard in their electric service rules. And don't forget, they measure at the service point. Not at the load.

Any voltage drop from the point of service to the load is on the owner / electrician.

 

[don_resqcapt19]

I am on vacation (which I really needed!). Just got a call from one of our commercial guys, he has 201 V at a pump on a 3p 120/208 Y service and thinks that is too low. The pump is running, and I am curious what the accepted tolerance from the power company usually is. I thought the low rnd was about 197, but I could be wrong....

In Illinois the acceptable voltage range is set by the Illinois Commerce Commission.

Illinois Commerce Commission JCAR rules
Section 410.300 Voltage Regulation
a) Standard voltage. Each entity supplying electrical energy for general use shall adopt a standard service voltage of 120 volts (when measured phase to neutral) and shall maintain the service voltage within the allowable variations from that value at all times.

b) Allowable voltage variations. For service rendered at the standard service voltage, voltage variations as measured at any customer's point of delivery shall not exceed a maximum of 127 volts nor fall below a minimum of 113 volts for periods longer than two minutes in each instance. For service rendered at voltages other than the standard voltage value, voltage variations as measured at any customer's point of delivery shall not exceed 10% above or below the service voltage for a longer period than two minutes in each instance.

c) Variations of voltage in excess of those specified above shall not be considered a violation of this Section if caused:
1) by operations of a retail customer in violation of an agreement with or the rules of the entity;
2) by the operation of apparatus on a retail customer's premises that results in large inrush currents;
3) by infrequent and unavoidable fluctuations of short duration due to system operation; or
4) by acts of nature or other situations beyond the entity's control.

Since this service supplies 120 volts line to neutral, it is my opinion that the acceptable line to line voltage is 196 to 220 volts under the Illinois Commerce Commission Rules.

 

[Deltaforce]

I am curious what the accepted tolerance from the power company usually is.

They follow ANSI C84.1, American National Standard for Electric Power Systems and Equipment—Voltage Ratings (60 Hertz).
For a residential nominal voltage of 120 V, the standard specifies a Range A of 114–126 V, which is a variation of ±5%.