Best LED Bypass Capacitors for Smart Lighting: 2025 Expert Review
Oli at OR Electrics
Fully Qualified 18th Edition Electrician
One of the most common complaints I get from homeowners upgrading to smart switches or retrofitting LEDs is the dreaded 'ghosting'. You switch the light off, but it continues to glow faintly, or it flickers like a disco. In the older properties we have here in Leeds, particularly those lacking a neutral wire at the switch, this is a frequent headache.
The solution is usually a simple component called a bypass capacitor (or suppressor). It acts like a sponge, soaking up the leakage current that causes low-power LEDs to misbehave. However, buying the wrong one can be dangerous if it isn't rated for mains voltage.
In this review, I'm looking at three options available to the public: a budget-friendly pack for quick fixes, a large repair kit for electronics enthusiasts, and a heavy-duty option for stubborn interference.
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Specs vs. The Real World
The Spec: "Installation Location"
"Install the capacitor behind the light switch."
Actually, bypass capacitors work best when installed across the switched live and neutral at the *light fitting* (the ceiling rose), not the switch. There is rarely enough room in a back box, and paralleling it at the load is electrically superior.
The Spec: "X2 Safety Rating"
"Any capacitor will filter signals."
Absolutely not. For mains voltage (230V), you MUST use an 'X2' rated safety capacitor. These are designed to fail safely (without catching fire) if a surge occurs. Never use standard DC capacitors across mains wiring.
My Top 3 Recommendations
Three options to cover different needs and budgets
Acmerota 10 Pcs LED Capacitor Fits for LED Light Switch, 0.22uf 275VAC X2 MKP
ACMEROTA
This is your standard go-to solution for the 'no neutral' smart switch flicker. The 0.22uF capacitance is the sweet spot for absorbing leakage current without wasting energy. It's properly X2 rated for 275V AC, meaning it's safe for UK mains usage.
The Good
- Includes basic connectors (saves buying Wagos separately)
- Correct X2 safety rating for UK mains
- Compact size fits easily inside ceiling roses
The Bad
- Leads are slightly thin
- Connectors provided are budget quality; I'd prefer lever connectors
Installer Tip:
These are ideal for correcting the 'ghost glow' on bedroom pendants. Ensure you wire it across Switched Live and Neutral at the ceiling rose. The included connectors are handy, but make sure they bite the wire firmly; give it a tug test.
Priced at £5.89 at the time of writing
Check Price on AmazonAUKENIEN Electrolytic Capacitor Kit 23 Values 288pcs
AUKENIEN
I'm including this as a 'Quality' option for a specific reason: driver repair. These are Electrolytic DC capacitors. You CANNOT use these across mains AC to stop flicker (they will pop). However, if you are a competent confident DIYer repairing a blown LED driver circuit board or building low-voltage smart home project, this is a comprehensive, high-quality kit.
The Good
- Huge range of values for electronics repair
- Neatly organised box with clear labelling
- High temperature tolerance (-40 to +105 degrees)
The Bad
- DANGEROUS if misused on AC mains (Not for direct loose wiring)
- Strictly for soldering into circuit boards
Installer Tip:
Sometimes an expensive LED driver fails because a single cheap capacitor inside has bulged. If you're comfortable soldering, this kit can save you replacing expensive hardware. Just ensure you observe polarity (positive/negative) which X2 caps don't require.
Priced at £14.99 at the time of writing
Check Price on AmazonZHUROUPU 10 Pcs Safety Capacitors Polypropylene Film 0.33uF 275V X2 MKP
ZHUROUPU
Sometimes standard 0.22uF capacitors aren't quite enough to suppress stubborn interference or heavy 'ghosting' on larger LED arrays. These Zhuroupu caps are rated at 0.33uF, providing slightly stronger suppression. They are flame retardant and moisture-proof, making them a robust choice.
The Good
- Higher capacitance solves tougher flicker issues
- Robust, flame-retardant housing
- Includes wire nuts and end caps
The Bad
- Slightly larger physical size than the 0.22uF options
- Wire nuts provided are a bit bulky for tight UK back boxes
Installer Tip:
Use these if you have a smart dimmer that is still buzzing or flickering slightly with a standard capacitor. The extra capacitance often smooths out the 'noise' that cheap LED drivers struggle with. Discard the wire nuts and use proper Wago connectors for a neat finish.
Priced at £7.89 at the time of writing
Check Price on AmazonFrequently Asked Questions
What is LED 'ghosting' and why does it happen?
How do I install a bypass capacitor?
Can I use any capacitor for this?
Will a capacitor fix flickering when the light is ON?
Do I need an electrician to fit a bypass capacitor?
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