Residantial Branch Circuit Allowable Voltage Drop

The NEC really does not say any particular voltage drop is bad but there is a note that recomends 5% max. That's about 150 feet of #14 wire. If you are a long way from the panel that might be normal. Remember the wire goes up, down and around, not a straight line. Also bear in mind a 15a circuit will not usually have all of that load 150 feet out.

Questions to ask or subjects to investigate.

1. Are your connections tight? For the circuit in question are the outlets connected securely with tight screw terminals to the wires or are they back stabbed? Is it just one circuit or do you have problems with all circuits (like lights dimming, etc.)? Check the service panel for tight connections, especially at the neutral buss. If you don't know what you are doing, don't kill yourself, call an electrician.

1. Are you tallkng about a 15 Amp circuit with #14 wire? If so, do your 20 A circuits (check in the kitchen) perform better in terms of less voltage drop? Maybe your electrician did a poor job splitting up the loads to various circuits. Are you trying to run a big (>12000 BTU) air conditioner on a 15A circuit?

2. How about the overall voltage drop of the house in relation to your service distribution transfomer. How does your hot - to - hot

240 voltage hold up when major appliances (Electric Dryer, Electric Hot Water heater, Electric Range, Air Conditioner) are turned on?

1. If you have problems with #3 above, where is your house located in relation to the power company distribution transfomer? Are you at the end-of-the line? Do you share a transformer with your neighbors? How far are you away from the power company substation?

2. Do you have 200A service? 150A or 100A service? Is your service entrance cable properly sized for the service you do have? Is your load balanced? Do you have a good neutral connection?

From the limited information you have provided, it is impossible to tell if it is just a local problem (for one circuit) or something that might be related to your whole house and have possible external causes.

Beachcomber

You will find your answer in 90.1; 90.5 (C); 210.19 (A) (1) FPN No. 4; and 215.2 (A) (1) FPN No. 2. Section 90.1 (C) reads in part "This Code is not intended as a design specification". Section 90.5 (C) Reads in part "Explanatory material, ...is included in this Code in the form of fine print notes (FPNs). Fine print notes are informational only and are not enforceable as requirements of this Code." The two fine Print Notes I have copied below are the code advice on voltage drop but section 90.5 (C) makes it clear that FPNs are not enforceable. Voltage Drop is a design issue which is beyond the scope of the US National Electric Code.

90.1 Purpose. (A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity. (B) Adequacy. This Code contains provisions that are considered necessary for safety. Compliance therewith and proper maintenance will result in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use. FPN:Hazards often occur because of overloading of wiring systems by methods or usage not in conformity with this Code. This occurs because initial wiring did not provide for increases in the use of electricity. An initial adequate installation and reasonable provisions for system changes will provide for future increases in the use of electricity. (C) Intention. This Code is not intended as a design specification or an instruction manual for untrained persons. 90.5 Mandatory Rules, Permissive Rules, and Explanatory Material. (C) Explanatory Material. Explanatory material, such as references to other standards, references to related sections of this Code, or information related to a Code rule, is included in this Code in the form of fine print notes (FPNs). Fine print notes are informational only and are not enforceable as requirements of this Code. 210.19 Conductors ? Minimum Ampacity and Size. (A) Branch Circuits Not More Than 600 Volts. (1) General. Branch-circuit conductors shall have an ampacity not less than the maximum load to be served. Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size, before the application of any adjustment or correction factors, shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load. Exception: Where the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the allowable ampacity of the branch circuit conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load. FPN No. 4:Conductors for branch circuits as defined in Article 100, sized to prevent a voltage drop exceeding 3 percent at the farthest outlet of power, heating, and lighting loads, or combinations of such loads, and where the maximum total voltage drop on both feeders and branch circuits to the farthest outlet does not exceed 5 percent, provide reasonable efficiency of operation. See 215.2 for voltage drop on feeder conductors. 215.2 Minimum Rating and Size. (A) Feeders Not More Than 600 Volts. (1) General. Feeder conductors shall have an ampacity not less than required to supply the load as computed in Parts II, III, and IV of Article 220. The minimum feeder-circuit conductor size, before the application of any adjustment or correction factors, shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load. Exception: Where the assembly, including the overcurrent devices protecting the feeder(s), is listed for operation at 100 percent of its rating, the allowable ampacity of the feeder conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load. Additional minimum sizes shall be as specified in (2), (3), and (4) under the conditions stipulated. FPN No. 2:Conductors for feeders as defined in Article 100, sized to prevent a voltage drop exceeding 3 percent at the farthest outlet of power, heating, and lighting loads, or combinations of such loads, and where the maximum total voltage drop on both feeders and branch circuits to the farthest outlet does not exceed 5 percent, will provide reasonable efficiency of operation.

You will get a bigger fluctuation from the utility company. It could be as high as

10% to 15%