Voltage drop from the utility co.

Status
Not open for further replies.

frankft2000

Senior Member
Location
Maine
I'm new to running my own work so I have some bacic questions, please bear with me. When fiquring voltage drop for a service, do I use the distance from the power company's point of service, or do I use the distance from the power company's transformer. The reason I ask is because I have a place where the overhead lines run about 250 before they get to the meter and I'm trying to size my wire form the meter to the panel. Where do I start measuring from? Thanks
 
Re: Voltage drop from the utility co.

Your responsibility is from the service point in. My experience indicates that the Power Co will consider voltage drop on their own lines if need be. If your installing 250' of overhead downstream of the service point then you should consider voltage drop per 215.2 (A) (4) FPN #2
210.19 (A) (1)FPN #4 addresses Branch Circuit Conductors.

One rule of thumb is distance of run not to exceed voltage. This method is best left to that of an indicator giving notice as to when to crunch numbers.

BUT FPNS are not enforceable.

Charlie
 
Re: Voltage drop from the utility co.

Your local electric utility is generally required to maintain their voltage to within 5% of nominal. In Indiana, we are required the 5% in cities and 6% in towns less than 2500 population and rural areas.

The question is, Do we do that? The answer is, Sometimes, well most of the time. Consider the number of customers we have and the difficulty of trying to regulate the entire system to provide good voltage to all of them. With that said, we start out with about 4% over nominal at the substation or voltage regulators. As we go through the circuit, we will install capacitors (usually 1200 kVAR) to correct the power factor and cut down on the voltage drop (these are normally radio controlled). Our distribution engineers will design subdivisions and businesses to try to hold the voltage drop to within reason (the same as you do).

If the load grows or the design was not right, we end up with a voltage problem. It seems like we are always having voltage problems in the older, more densely populated areas of town where the load has grown on smaller transformers and small secondary conductors.

Now, what do we do about it? If there is a voltage problem and you call someone at the "light company", what is done about it? It depends on who shows up and what time of day it is. If it is towards the end of the shift and the trouble man is tired and it is boarder line, you may get a brush off. If it is border line and it earlier in the shift, it may be referred to a specialist to place a recording chart on the line to look for a trend and ways to fix the problem.

The problem may be in your meter. It is more likely to be in too small of a transformer, secondary, or distance from the transformer. None of these problems are easy to fix and it is worse in an underground subdivision. The problem is really bad if you are too far from a substation. Generally speaking, there will be no easy answers for the last one (another set of voltage regulators (big and ugly), a new substation (not in my back yard and we do not want another transmission line to ugly up the pristine landscape), capacitor banks, etc.) Some are great but expensive and ugly, others may or may not do any good.

Most of the time (unfortunately) it is the squeaking wheel that gets the grease. If someone tries to brush you off and you are sure it is the serving electric utility that is causing the problem, don't give up until they have fixed the problem. :D
 
Re: Voltage drop from the utility co.

Thank you for your responces. I wanted to ask this because in the situation I described above, the panel will be about 120 feet from the meter/disconnect. I'm geting the idea I guess that I should not have to upsize my 4/0 aluminum conductors and if the voltage drop is too high, then it would be the power company who whould have to make ammends. Am I assuming this right? Thanks
 
Status
Not open for further replies.
Top