Eaton’s Bussmann® Series Document Finder

Latest Article

415 V a.c. vs 690 V a.c. fuse l inks - Bigger gains from lower voltages

It’s time to consider 415V fuse protection rather than 690V argues Tony Garlinge-Warren, Senior Applications Engineer, Eaton.

It is said that ‘old habits die hard’ and one need look no further for proof than the electrical industry’s continued preference for specifying 690V fuse links when, in most cases, 415V fuses would be as, if not more, appropriate. We estimate that in the UK 90% of all electrical commercial and industrial applications would suit 415V fuses yet there appears to be an unswerving loyalty to 690V fuses, that sees them specified in far greater numbers than the applications merit.

Maybe it is time to take a fresh approach and embrace the choice of 415V fuses as the premier rating for electrical circuit protection? After all roughly 90% of applications can be catered with 415V fuses.

What should also be considered is the retrofit opportunity whereby 415V product can be switched in for existing 690V fuses, provided that the system voltage has been identified as 415V and that local regulations allow it. Too often a ‘like for like’ strategy is employed because approvals and paperwork say that this should be the case when technically there is no issue substituting 415V for 690V once the correct system voltage has been ascertained.

Notwithstanding that 415V is the electrical three-phase standard voltage in the UK, there are in addition a whole hosts of benefits that accrue from choosing fuses of this rating.

The industry will always talk about cost, and while unit prices of 415V products are likely to be less than comparable 690V products, it is cost in the ‘installed cost’ sense of the word that is really the important issue. The sheer versatility and flexibility of 415V products gives design engineers the scope to drive cost out of projects.

For instance the compact dimensions of the 415V format provide space saving opportunities in equipment, reducing material costs in the process, while the comprehensive range of available ratings means a precise choice of rating can be chosen rather than one that is over-specified and hence more expensive.

The 415V format fuses also come with a variety of mounting options - bladed or bolted tags – and generally are compatible with a wider range of ancillary products such as fuse holders and fused switches, again providing scope to achieve the optimum result in terms of system efficiency and cost. 

Typically 415V fuses are cooler running than their 690V counterparts with lower watts loss, hence less energy dissipated and increased system efficiency.

What’s more the applications for 415V are wide and varied, allowing greater scope for cost saving and system efficiencies. These include power distribution, cable protection, switched fuses and machine or equipment protection. Special motor rated fuses are used for industrial motor protection.

While there may be some hesitancy about adopting 415V over 690V, and rest assured there are applications for which only 690V will do, there are compelling reasons to make that move