Lights Flickering? When It's Normal vs. When to Worry
Lights flicker when the AC kicks on, or all the time? Here's how to tell whether it's a harmless voltage dip, a loose neutral, or a serious fault.
Quick answer
Usually this is brief voltage dip (AC startup, microwave), dimmer / LED bulb incompatibility, or loose neutral connection, listed in the order we actually find them in Utah homes. Run the safe checks below first; if the fix isn't one of them, a licensed tech can diagnose it on-site for a $39 dispatch fee, waived when you approve the repair.
Flickering lights have wildly different causes depending on the pattern. Brief dim during AC startup is normal; constant flicker on one circuit is a connection problem; whole-house flicker is a service-side issue.
Diagnostic
Most likely causes (in order)
Walk through the list top-to-bottom. The first cause matches roughly half of cases we see in Utah; if it doesn't fit your symptoms, move to the next.
Brief voltage dip (AC startup, microwave)
When a high-current device starts (AC compressor, microwave, hair dryer), it pulls a current spike. Service voltage drops briefly. Lights dim for 0.5-2 seconds, then recover. NORMAL on most homes.
Dimmer / LED bulb incompatibility
Old triac-based dimmers + modern LED bulbs = visible flicker, especially at low brightness. Need a dimmer rated 'LED-compatible' (CL/MLV).
Loose neutral connection
Loose neutral wire (at panel or junction box) = unbalanced 120V. One leg drops, lights on that leg flicker; lights on the other leg may go bright. Genuine fire/equipment-damage risk.
Failing breaker or burned panel busbar
Federal Pacific or Zinsco panels: aluminum busbar oxidation creates intermittent connections to breakers. Lights on that circuit flicker as the connection comes and goes.
Service-side issue (utility)
Whole-neighborhood flicker = utility issue (transformer, line, weather). Whole-house but only your home flicker = service entrance or main breaker problem.
DIY first
Safe checks you can do today
Each step is labeled by safety level. Stop at any “Pro only” step, that's where the diagnostic crosses into work that needs gauges, multimeters, or live electrical access.
Identify the pattern
Safe DIYBrief dim with AC/microwave: normal. One circuit constant flicker: dimmer/LED. Whole-house: service issue. Random isolated flicker: loose connection.
Try replacing dimmer + bulb
Safe DIYDimmer/LED incompatibility is cheap to fix. An LED-rated dimmer + matched LED bulb. Confirms it's not a more serious issue.
Check whole-house flicker timing
Safe DIYAffecting only your home? Service-side issue between transformer and your panel. Affecting whole street? Utility problem, call Rocky Mountain Power.
Stop here if isolated to one circuit and persistent
Pro onlyLoose connections in a panel or junction box = live electrical work. Some are also genuine fire hazards. Call.
Stop and call
When you should call us instead
- Lights bright then dim irregularly, possible loose neutral (electrical hazard)
- Flicker accompanied by burning smell, fire risk, call today
- FPE Stab-Lok or Zinsco panel with flickering, panel replacement candidate
- Multiple devices on the same circuit damaged or failing prematurely, voltage problem damaging electronics
Not sure if it's a real problem?
Our AI walks you through the same triage a senior tech would, figures out whether you need a service call or whether it's something simpler you can handle yourself. Or skip ahead and book a diagnostic visit.
FAQ
Frequently asked questions
Are flickering LED lights damaging anything?
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Cosmetic-only flicker on a dimmer: no. Voltage-dip flicker affecting a whole circuit irregularly: yes, sensitive electronics on that circuit (computers, TVs, AV gear) can fail prematurely. Diagnose persistent flicker; don't ignore it.
Related
More diagnostic guides
Other common Utah-home symptoms with the same step-by-step diagnostic format.
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Burning smell = stop using outlet, kill power to circuit, call.