How to Find the Correct Replacement RCD for Your Consumer Unit

If an RCD in your consumer unit needs replacing, it is important to identify the correct device rather than simply purchasing another RCD that looks similar.

RCDs are available from manufacturers including Wylex, Hager, Crabtree, Schneider, MK and other electrical brands, with numerous different ranges and generations produced over the years.

Two RCDs can have the same current and residual-current ratings while still not being suitable replacements for each other.

This guide explains what information to check when trying to identify a replacement RCD.

1. Identify the Manufacturer

Start by identifying who manufactured your existing consumer unit and RCD.

Common manufacturers found in UK installations include:

  • Wylex

  • Hager

  • Crabtree

  • Schneider Electric

  • MK

  • MEM / Eaton

The manufacturer's name or logo will normally be visible on the front of the consumer unit and protective devices.

Don't assume that an RCD from another manufacturer can be installed simply because it looks similar.

2. Find the RCD Model Number

The model or product number is one of the most useful pieces of information when searching for a replacement.

It may be printed on the front or side of the RCD.

Searching using the exact product number can help identify:

  • The original specification

  • The consumer unit range

  • Whether the product has been discontinued

  • Potential manufacturer-approved replacement options

If you are unsure which number is the model number, take clear photographs of all visible markings.

3. Check the Current Rating

Look for a rating such as:

40A

63A

80A

100A

This is the RCD's rated current.

Do not assume that choosing an RCD with a higher current rating automatically makes it a suitable replacement.

The rating needs to be appropriate for the design of the installation.

4. Check the Residual-Current Rating

Many RCDs installed in domestic consumer units are marked:

30mA

This is the rated residual operating current.

Other ratings such as 100mA and 300mA also exist for different applications.

These ratings are not interchangeable simply because the RCD physically fits.

If the existing device is 30mA, don't purchase a 100mA device on the assumption that the larger number represents an upgrade.

5. Identify the RCD Type

The RCD type is another important part of the specification.

Common types include:

Type AC

Type A

with Type F and Type B also used for applications requiring their particular characteristics.

Older UK consumer units frequently contain Type AC RCDs, while Type A devices are increasingly common in newer installations.

The type can normally be identified from the markings or waveform symbols on the front of the device.

See our Type A vs Type AC RCD Guide for more information.

6. Check the Number of Poles

The replacement must have the appropriate pole configuration for the installation.

Many domestic single-phase consumer units use two-pole RCDs.

Other installations can use different configurations.

Do not assume that two devices are equivalent simply because their front dimensions appear similar.

7. Identify the Consumer Unit Range

Knowing the manufacturer alone isn't always enough.

Manufacturers can produce multiple generations and ranges of consumer units.

For example, two devices may both carry the same manufacturer's branding but belong to different product families.

This is particularly important with older or discontinued consumer units.

Look for:

  • Consumer unit model number

  • Range name

  • Labels inside or on the enclosure

  • Existing breaker model numbers

  • RCD model number

Sometimes the surrounding MCB or RCBO model numbers can also help identify the range.

8. Don't Rely on Physical Appearance

This is one of the easiest mistakes to make when purchasing replacement electrical equipment.

Two RCDs may:

  • Look almost identical

  • Have the same number of modules

  • Have similar terminals

  • Have the same 80A rating

  • Both be 30mA devices

and still not be suitable substitutes for each other.

Physical fit alone does not establish compatibility with a consumer unit assembly.

9. Don't Assume Different Brands Are Interchangeable

An 80A 30mA Type A Wylex RCD and an 80A 30mA Type A Hager RCD may have apparently identical headline specifications.

That does not make them interchangeable.

The protective devices installed within a consumer unit should be suitable for that particular assembly and installed in accordance with the manufacturer's requirements.

The safest starting point when searching for a replacement is therefore the existing manufacturer and consumer unit range.

10. What If My RCD Has Been Discontinued?

This is common with older consumer units.

Electrical manufacturers regularly update their product ranges, meaning the exact RCD originally installed may no longer be manufactured.

If this happens, don't immediately assume the entire consumer unit needs replacing, but equally don't assume that the manufacturer's newest RCD will fit the older board.

First identify the exact discontinued product.

From there, you can investigate whether:

  • The manufacturer specifies a replacement

  • A later compatible device exists

  • Original discontinued stock is still available

  • The installation requires another solution

Older and discontinued electrical equipment is one of the areas where having the exact product number becomes particularly valuable.

What Information Should I Send When Asking for a Replacement?

If you're asking an electrician, supplier or ReCircuit Resale to help identify an RCD, provide as much information as possible.

Ideally send:

1. A clear photograph of the complete consumer unit

This helps identify the manufacturer and range.

2. A close-up photograph of the RCD

Make sure the markings can be read.

3. The RCD model number

Include any letters, numbers or symbols.

4. The current rating

For example 63A, 80A or 100A.

5. The residual-current rating

For example 30mA.

6. The RCD type

For example Type A or Type AC.

With this information, identifying the correct device becomes considerably easier.

Quick Replacement RCD Checklist

Before ordering a replacement, check:

Manufacturer ✓

Consumer unit range ✓

Model/product number ✓

Current rating ✓

Residual-current rating ✓

RCD type ✓

Number of poles ✓

Manufacturer compatibility ✓

If you're missing some of this information, don't guess based on appearance alone.

Need Help Finding a Replacement RCD?

At ReCircuit Resale, we stock a range of new, new-other and used RCDs, including current and discontinued electrical equipment.

Our stock regularly includes products from manufacturers such as Wylex, Hager, Crabtree and other major electrical brands.

If you're struggling to find an RCD for an older consumer unit, send us:

A clear photo of the consumer unit + a close-up of the existing RCD

Where possible, include the model number.

We can then help identify the product and check whether we have a suitable replacement available.

This guide is intended to assist with product identification. Selecting and installing an RCD requires consideration of the electrical installation as a whole. Work within consumer units and fixed electrical installations should be carried out by a suitably competent person in accordance with BS 7671 and the relevant manufacturer's instructions.