Rubber wiring in London homes: how to spot it and why it matters

Most London homes have been rewired at least once. Many have been rewired in parts, at different times, by different people. That is how old rubber insulated cable survives: a kitchen gets new wiring, the bathroom gets new wiring, and one lighting circuit in the loft is left as it was.

This guide explains what rubber wiring looks like, why it fails, and what to do if you think you have it. If you want it found and tested, our electrical fault finding page explains how a visit runs.

What rubber wiring is

Before modern PVC cable, house wiring used copper conductors insulated with vulcanised rubber. Rubber was often covered in a cotton or fabric braid, and some runs were sheathed in lead. Electrical Safety First notes that cables coated in black rubber were phased out in the 1960s, and that cables coated in lead or fabric are even older and may well need replacing.

The rubber was fine when new. Over decades it reacts with air and heat, hardens and starts to crack. In lofts and above ceiling lights, where it gets hottest, it can crumble when touched.

How to spot it

You do not need to open anything to look for these signs:

Where to look	Sign of older wiring
Consumer unit or fuse box	Wooden backing board, porcelain fuse holders, fuse wire, or cables entering in black rather than grey or white
Sockets	Round pin sockets, or sockets mounted in the skirting board
Light switches	Old brass or round toggle switches, or switches with no earth to a metal plate
Loft	Black cable with a cracked fabric or rubber cover, cable clipped to joists and running to old ceiling roses
Under floorboards	Twisted or taped joins, black cable mixed in with newer grey cable
Meter cupboard	Very old meter tails or a fuse box that looks much older than the rest of the home

If you see bare copper anywhere, or insulation crumbling away, leave it alone and treat that circuit as unsafe.

Why it matters

Rubber wiring causes three kinds of problem.

Exposed copper. When the insulation cracks, live copper is exposed. That can cause a shock if touched, or a short circuit if two wires touch each other.

No earth. Many older lighting circuits had no earth conductor at all. That means metal light fittings and switch plates have no path to earth if something goes wrong. Our guide to a shock or tingle from a tap or radiator explains why earthing matters.

Heat and overload. Old circuits were designed for far less load than a modern home uses. Add LED drivers, loft conversions, extra sockets and electric heaters, and the old cable runs hotter than it was ever meant to.

London Fire Brigade lists warning signs of loose or dangerous wiring: scorch marks, flickering lights, hot plugs and sockets, and fuses that blow or circuit breakers that trip for no obvious reason.

Havering homes: the changeover years

Romford and the rest of Havering are a little different from inner London. The VOA’s housing stock figures show that only 5% of Havering’s homes were built before 1919, the lowest share of the areas we cover. Instead, 36% were built between 1919 and 1939 and another 35% between 1945 and 1972. Havering also has the highest share of bungalows of the areas we cover, at 9%.

That puts a large part of Havering’s housing in the decades when rubber cable was still common, or was just giving way to PVC. Gidea Park, the Harold Hill estate, and the semis and bungalows of Hornchurch and Upminster were all built or first wired in those years. Many have since been fully rewired. Some have not, or have one or two original circuits left, often the lighting.

Bungalows are worth a special mention. Their lighting cables usually run through the loft, which gets very hot in summer and cold in winter. That is where rubber insulation ages fastest. If you live in a bungalow in Romford or elsewhere in Havering and have never had the wiring checked, the loft is the first place an electrician will look.

What to do if you think you have it

1. Do not disturb it. Leave cables where they are and avoid storing things on them in the loft.
2. Do not overload those circuits. Avoid electric heaters and extension leads on rooms you suspect.
3. Book an inspection. An Electrical Installation Condition Report, or EICR, tests every circuit and records what is found. Electrical Safety First recommends one at least every 10 years for owner occupied homes, and every 5 years for rented homes.
4. If you rent it out, it is a legal duty. Landlords in England must have the installation inspected and tested at least every 5 years under the electrical safety standards regulations.

What an electrician will do

On an inspection or fault finding visit, an electrician will:

• Look at the consumer unit and identify the cable types on each circuit
• Test insulation on each circuit to see if current is escaping
• Check whether lighting circuits have an earth
• Look in the loft and at sample points such as switches and sockets
• Tell you which circuits are a risk now and which can be planned for later

The result may be a small job, replacing one or two circuits, or advice to plan a rewire. A new circuit is notifiable work in England under Part P, and so is replacing a consumer unit. The Planning Portal explains how notification works.

Next step

If you have spotted black rubber cable, round pin sockets or wire fuses, get the installation checked before you add any new load. Request a visit through our fault finding service. The price is confirmed after a look at the job.