What does it mean when my lights dim randomly in my New Brunswick home?

Random Light Dimming: Causes and Solutions for NB Homes

Lights that dim briefly when an appliance kicks on are usually normal. Lights that dim randomly, repeatedly, or stay dim for extended periods indicate a problem that needs diagnosis.

Normal vs. Abnormal Dimming

Normal (usually harmless):

• Brief dim (under 1 second) when the furnace, AC, well pump, or fridge starts


• Slight dim when a high-draw appliance (microwave, hair dryer) turns on


• Consistent with one specific appliance starting

Abnormal (needs investigation):

• Dimming that lasts more than 2 seconds


• Random dimming with no apparent trigger


• Dimming in some rooms but not others


• Dimming accompanied by flickering, buzzing, or warm outlets


• Dimming that's getting progressively worse


• Lights going brighter than normal (overvoltage — potentially dangerous)

Cause 1: Loose Connections (Most Dangerous)

Loose electrical connections create resistance. Under load, that resistance causes voltage drop to downstream devices (dimming) and generates heat (fire risk).

Where to look:

• Panel connections — loose bus bar connections, loose breaker terminals


• Service entrance — loose connection at the meter base, the mast, or the weatherhead


• Outlet and switch terminals — especially backstab (push-in) connections that loosen over time


• Neutral wire connections — a loose neutral is particularly problematic because it affects all circuits sharing that neutral

Why it's dangerous: A loose connection is an active fire hazard. The resistance generates heat proportional to the current flowing through it. Under heavy load (winter heating, cooking), a loose connection can reach temperatures that ignite surrounding materials.

Fix: A TSANB-licensed electrician uses a thermal imaging camera ($300–$500 for the scan) to identify hot spots at connections throughout the panel and accessible wiring. Tightening or replacing the affected connections resolves the dimming and eliminates the fire risk. Cost: $100–$500 depending on the scope.

Cause 2: Overloaded Circuit

When a circuit is loaded near its capacity, every additional device causes a noticeable voltage drop.

Example: A 15A circuit serving a bedroom with a space heater (12.5A) leaves only 2.5A for everything else. Turning on a lamp (0.5A) barely registers, but plugging in a hair dryer (10A) would trip the breaker — and running a vacuum (8A) causes visible dimming before the breaker trips.

Fix: Redistribute loads across circuits or add a new circuit for high-draw devices. Cost: $300–$600 for a new circuit.

Cause 3: Undersized Panel or Service

A 60A or 100A panel serving a home with electric heat, a dryer, a stove, and modern appliances may not deliver enough current during peak demand. The entire house dims when multiple large loads run simultaneously.

Common in NB: Older homes in Moncton, Saint John, Fredericton, and rural areas with original 60A or 100A panels that were never upgraded. Adding a heat pump, EV charger, or hot tub to an already-loaded panel makes this worse.

Fix: Panel upgrade from 100A to 200A. Cost: $2,500–$4,500. This is the permanent solution for whole-house dimming under heavy load.

Cause 4: Utility-Side Problem

If dimming affects your entire house AND your neighbours report similar issues, the problem is on NB Power's side:

• Failing transformer — the neighbourhood transformer may be overloaded or deteriorating
• Loose connection at the pole — the connection between NB Power's lines and your service drop can loosen over time
• Overloaded neighbourhood feeder — too many homes drawing power from the same feeder line, especially during cold snaps when everyone's baseboard heaters are at maximum

Fix: Report to NB Power at 1-800-663-6272. They'll investigate at no cost to you. If the problem is their equipment, they'll repair or replace it. If it's the connection at the pole, they'll address that too. Turnaround is typically 1–5 business days for non-emergency voltage issues.

Cause 5: Failing Main Breaker or Neutral

A deteriorating main breaker or a corroded/loose main neutral connection can cause voltage imbalances between the two 120V legs of your electrical service. Symptoms:

• Some lights dim while others get brighter
• Dimming that shifts between different areas of the house
• Appliances on 240V (stove, dryer) working fine while 120V circuits fluctuate

This is called a floating neutral or lost neutral and it's dangerous — overvoltage on one leg can damage electronics and appliances. If you notice some lights getting brighter than normal, turn off the main breaker and call an electrician immediately.

Fix: Electrician repairs the neutral connection or replaces the main breaker. Cost: $150–$500 for the repair, or part of a panel upgrade if the panel is old.

Diagnostic Steps

Note the pattern — when does it happen, which lights are affected, how long does it last?

Check the breaker panel — feel for warm breakers (with the panel door open, carefully touch breaker handles — they should all be the same temperature)

Ask neighbours — if they're experiencing the same thing, call NB Power

Check for correlation — does it happen when a specific appliance runs?

Call an electrician if the dimming is persistent, random, affects multiple rooms, or is accompanied by other symptoms (buzzing, warm outlets, burning smell)

A diagnostic visit costs $80–$175 in most NB communities. Given that loose connections are a fire hazard, this is well worth the cost for peace of mind.

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