FAQ
TL;DR: Utilities sometimes apply a 5% reduction during peak demand, which users experience as low voltage; as one poster put it, "standard 5 percent reduction." [Elektroda, msajaa 123, post #21674280]
Why it matters: If you’re on a long rural feeder and wondering how to fix weak voltage at home, this FAQ shows root causes and practical next steps for homeowners, facility managers, and electricians.
Quick Facts
- Reported setup: ~30 km distribution feeder from a 132 kV grid station serving homes with chronic undervoltage. [Elektroda, Awais Khan, post #21674271]
- Users observed 30–50 V at home inputs, rising to ~100 V during rain; regulators used to boost to 180–220 V. [Elektroda, Awais Khan, post #21674275]
- Common technical culprits listed: overload, cable size, phase/neutral faults, loose or corroded connections. [Elektroda, msarts 123, post #21674279]
- Longer lines and in‑between loads increase voltage drop toward the end of the feeder. [Elektroda, Shaun marsh, post #21674283]
- Mitigations discussed: transformer tap changes, higher‑capacity local transformers, and adding new lines/pole transformers. [Elektroda, richard gabric, post #21674274]
What typically causes low voltage on long rural feeders?
Primary drivers are feeder length, cumulative load, and conductor or connection issues. Heavy startup currents and faults create sags that feel like undervoltage. Local overloads and poor phase balance worsen drop toward the feeder end. Users in the thread reported these exact patterns on a long line. [Elektroda, Shaun marsh, post #21674283]
Why would voltage improve when it rains?
One possibility is changes in ground resistivity affecting systems that use or leak to ground. Wet soil can alter return paths and losses. A contributor suggested checking for ground return effects if rain correlates with higher measured voltage. Log voltage and weather together to confirm. [Elektroda, richard gabric, post #21674276]
Could utility peak‑load actions explain my dim lights?
Yes. During high‑demand periods, utilities may apply about a 5% reduction per home. That deliberate drop reduces system stress but shows up as weaker voltage and performance at the socket. "Standard 5 percent reduction" was noted in the discussion. [Elektroda, msajaa 123, post #21674280]
How do overloaded or imbalanced phases cause low voltage?
If one phase carries more current than others, its voltage falls under load. Unequal household loading or weak conductors can skew currents. The overworked phase sags, creating flicker and device issues on that leg. Balancing loads restores margin and stability. [Elektroda, msec msec, post #21674282]
What should I check first inside my property?
Inspect for loose terminations, corroded lugs, undersized conductors, and a compromised neutral. Phase loss or a weak neutral can mimic supply undervoltage. Correcting these raises delivered voltage without utility changes. Use a qualified electrician for live work. [Elektroda, msarts 123, post #21674279]
Is cable size along the street a factor?
Yes. Smaller conductors have higher resistance and voltage drop under load. Long laterals with undersized wires compound drop to end users. Upgrading conductor size or shortening runs reduces end‑of‑line sag. [Elektroda, msarts 123, post #21674279]
Can transformer tap settings help low voltage?
Substation transformers often have taps to raise secondary voltage and offset feeder losses. Street‑level transformers might lack adjustable taps, so utilities may need to change or upsize them. One expert solved a regional sag with higher‑voltage lines and many new pole transformers. [Elektroda, richard gabric, post #21674274]
What is a voltage sag, in plain terms?
A voltage sag is a short‑duration drop in RMS voltage, often from faults or motor starts. Repeated sags can feel like chronic undervoltage if the system stays stressed. "Sags are usually caused by system faults," noted a contributor. [Elektroda, Kevin Angelo Ma, post #21674272]
My inlet shows 30–50 V but appliances still run using a regulator—safe?
Not safe long‑term. Boost regulators mask supply issues and can overheat or fail under severe undervoltage. Address upstream causes with the utility and verify neutral integrity. Regulators are stopgaps, not fixes. [Elektroda, Awais Khan, post #21674275]
What is a feeder in power distribution?
A feeder is the medium‑voltage line carrying power from a substation to distribution areas. Its length and loading directly influence end‑user voltage. Very long feeders show higher cumulative drop. [Elektroda, Shaun marsh, post #21674283]
How can I document the issue so the utility takes action?
Log voltage at regular intervals, note dates and weather, and correlate with load patterns. A contributor recommended year‑long recording with matching meteorological data to prove trends and triggers. Present the record with timestamps. [Elektroda, richard gabric, post #21674278]
Could mid‑feeder industrial loads be dragging everyone down?
Yes. Large loads near the feeder start can depress voltage downstream. Their inrush and steady demand increase voltage drop for end users. Coordination with the utility may require capacity upgrades or sectionalizing. [Elektroda, Awais Khan, post #21674275]
What field fixes have worked in similar cases?
Successful remedies included installing higher‑voltage lines, adding around eighty new pole transformers, and upsizing local capacity. After those upgrades, the regional undervoltage disappeared, according to one practitioner. [Elektroda, richard gabric, post #21674274]
How do I balance phases at home to reduce sag?
Spread large appliances across phases, verify equal loading, and ensure sound neutral connections. An electrician can measure currents and rebalance circuits at the panel. Balanced phases reduce drop and flicker. [Elektroda, msec msec, post #21674282]
Three‑step: How do I measure and prove low voltage over time?
- Install a safe RMS logger at the main, set 1–5 minute intervals.
- Record for weeks; tag rain, heat, and peak hours.
- Compare traces to events; share plots with your utility for mitigation talks. [Elektroda, richard gabric, post #21674278]
Edge case: Could a bad neutral mimic extreme undervoltage?
Yes. A failed neutral can shift voltages between legs, showing very low readings on one side. It can damage equipment quickly. Inspect and repair before pursuing feeder upgrades. [Elektroda, msarts 123, post #21674279]
