In the electrical industry, especially in conduit systems, two British standards often come up: BS31 and BS4568. Both specify requirements for steel conduits used in electrical wiring protection, but they were developed in different eras and reflect evolving manufacturing technologies and safety expectations. This article explores what each standard entails, why their specifications differ, and how they’re used today.

BS31: General Steel Conduit Standard

BS31 is a broad standard that covers various types of steel conduit and fittings, including plain conduit, screwed conduit, and their associated fittings such as couplers, boxes, and elbows. This standard is designed to accommodate a wide range of electrical installation needs, especially in areas where higher mechanical protection is required.

• Applications: BS31 conduits are commonly used in residential, commercial, and industrial electrical installations. They are often chosen for environments where mechanical strength is essential.

• Examples: Threaded steel conduits specified under BS31 provide solid mechanical strength and are suitable for general-purpose electrical wiring systems.

BS4568: Galvanized Iron (GI) Conduit Standard Heavy Gauge (Screwed)

Galvanized Conduit to B.S. 4568:1970, Class 3                  Hot Dip Galvanized Conduit, Class 4

BS4568 focuses specifically on galvanized iron (GI) conduit, known for its durability and resistance to harsh environmental conditions. This standard defines detailed specifications for GI conduits, including wall thickness, threading, and construction features that enhance performance in demanding applications.

• Applications: BS4568 GI conduits are suitable for a wide range of installations, including industrial, commercial, and residential buildings. Their robust design makes them ideal for both indoor and outdoor use.

• Examples: Rigid steel conduits with metric threads, steel couplings, and thread protectors are all part of the BS4568 specification.

As you can see that BS31 and BS4568 is very similar, but one of the key difference is the length difference. 

For bs4568, the standard length is 3750mm without coupler, and for bs31, the standard length is 3810mm without coupler, but length 3048mm is also avalible.

In conclusion,

Both BS31 and BS4568 play important roles in ensuring the safety and reliability of electrical conduit systems. However, BS4568 is considered the more modern and specialized standard, offering enhanced durability and performance for galvanized iron conduit installations. By understanding the distinctions between these two standards, electricians, contractors, and project planners can make informed decisions when selecting conduits for specific applications.