What’s That Green Goo?

The Hidden Danger in Older Electrical Installations

If you’ve ever taken a faceplate off a socket or light switch and spotted a sticky green substance oozing from the cables, you’re not alone—and you’ve just met what electricians call “green goo.” 🧪

It might look harmless (or just gross), but this mysterious slime is actually a sign of deeper trouble in your electrical system.At Keswick Electrical Services Ltd, we’ve seen it plenty of times—and we’re here to explain what it is, why it happens, and what you should do if you spot it in your home.

So, What Is Green Goo?

“Green goo” is the result of a chemical breakdown in the insulation of old PVC electrical cables, typically from the late 1960s to early 1970s. Back then, manufacturers used di-2-ethylhexyl phthalate (DEHP) as a plasticiser to make the cable insulation more flexible.

Over time, especially under the effects of heat and electrical load, the DEHP starts to migrate out of the plastic and mixes with the copper in the cable. The result? A sticky, greenish liquid that slowly seeps out of the cable ends.

Is It Dangerous? Unfortunately, Yes...

While green goo isn’t hazardous to your health (unless you try to taste it – please don’t!), it is a sign that your electrical system could be compromised. Here’s why:

• Insulation Breakdown – The cables affected by green goo have degraded insulation, which can lead to short circuits or even electric shocks.
• Damaged Accessories – The goo can corrode terminals in sockets, switches, and other accessories, causing poor connections and overheating.
• Compromised Protective Devices – Goo can interfere with protective devices like MCBs or RCDs, reducing their effectiveness and increasing fire risk.
• Increased Fire Hazard – Electrical faults from damaged cables or connections are one of the most common causes of house fires.

How Can You Spot It?

Keep an eye out for:

• Green slime leaking from socket or switch faceplates
• Discolouration or stickiness around the terminals
• Tripping circuits for no apparent reason
• Burning smells or heat from accessories

If you suspect green goo, don’t ignore it or try to clean it up yourself—it’s usually a sign that a rewire is needed.

How Keswick Electrical Services Ltd Can Help

We’ve helped many homeowners in Bromley and the surrounding areas deal with this exact problem. Our fully qualified electricians can:

• Inspect your installation to assess the extent of the damage
• Test for safety and confirm if rewiring is necessary
• Replace affected circuits or carry out a full rewire using modern, safe materials
• Provide peace of mind with certification and a professional finish you can trust

Time to Act?

Green goo won’t go away on its own—in fact, it usually gets worse. If your home was wired in the 60s or 70s and hasn’t been checked in a while, now’s the time.

Contact Keswick Electrical Services Ltd today for a free consultation or to book an inspection. Let’s keep your home safe, secure, and goo-free!