Which company owns MAC address prefix 00:C3:43?

MAC address prefix 00:C3:43 is registered to E-T-A Circuit Breakers Ltd in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:C3:43 has a network interface built by E-T-A Circuit Breakers Ltd.

What is the OUI 00:C3:43?

00:C3:43 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to E-T-A Circuit Breakers Ltd. It covers every address from 00:C3:43:00:00:00 to 00:C3:43:FF:FF:FF, or 16,777,216 addresses in total. It is also written 00-C3-43.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 00:C3:43:00:00:00 that is 00:C3:43 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.

Where is E-T-A Circuit Breakers Ltd located?

E-T-A Circuit Breakers Ltd is listed at 6 Telford Close Aylesbury Buckinghamshire GB HP198DG in the IEEE OUI registry entry for 00:C3:43. This is the address the organization registered with the IEEE, which may differ from its current operating address.

E-T-A Circuit Breakers Ltd

MAC address prefix 00:C3:43 is registered to E-T-A Circuit Breakers Ltd in the IEEE OUI registry. Any device whose MAC address begins with 00:C3:43 has a network interface built by E-T-A Circuit Breakers Ltd. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address — it covers every MAC from 00:C3:43:00:00:00 to 00:C3:43:FF:FF:FF.

OUI prefix: 00:C3:43
Hyphen form: 00-C3-43
MAC range: 00:C3:43:00:00:00 – 00:C3:43:FF:FF:FF
Addresses in block: 16,777,216
Organization: E-T-A Circuit Breakers Ltd
Address: 6 Telford Close Aylesbury Buckinghamshire GB HP198DG
Source: IEEE OUI registry

Have a full MAC address? Look it up— we'll also tell you if it's a randomized (private) address rather than a real manufacturer prefix.

Assignment history (2)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2020-08-05Assigned to "E-T-A Circuit Breakers Ltd"
archived source →
2026-07-17Assigned to "E-T-A Circuit Breakers Ltd"

Nearby in the registry

The prefixes assigned immediately before and after 00:C3:43:

FAQ

Which company owns MAC address prefix 00:C3:43?: MAC address prefix 00:C3:43 is registered to E-T-A Circuit Breakers Ltd in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:C3:43 has a network interface built by E-T-A Circuit Breakers Ltd.
What is the OUI 00:C3:43?: 00:C3:43 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to E-T-A Circuit Breakers Ltd. It covers every address from 00:C3:43:00:00:00 to 00:C3:43:FF:FF:FF, or 16,777,216 addresses in total. It is also written 00-C3-43.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 00:C3:43:00:00:00 that is 00:C3:43 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.
Where is E-T-A Circuit Breakers Ltd located?: E-T-A Circuit Breakers Ltd is listed at 6 Telford Close Aylesbury Buckinghamshire GB HP198DG in the IEEE OUI registry entry for 00:C3:43. This is the address the organization registered with the IEEE, which may differ from its current operating address.