Make Your Off-Grid Wiring 4x More Reliable

According to some claims, ferruled cable connections can increase the reliability of connections by up to 4x over non-ferruled connections.

Multi-stranded cables are almost always used in solar, wind and battery based systems. This offers the advantages of flexibility, however the fine wire stands can be easily damaged when being connected.

10 benefits of using ferrules on your solar pv installation :

1. Eliminates stray strands, increasing safety andamp; reliability.
2. Improves contact quality, reducing contact resistance and heat.
3. Crimped cable ends are more resistant to oxidation, especially in salty / harsh environments. 
4. Reduces clamping damage to cable ends, less broken strands.
5. More secure mechanical contact. Crimping pattern is less likely to slip under pressure.
6. Easier cable re-termination / modifications.
7. Ferrules help to expand systems neatly and reliably, in particular with dual cable (2-1) ferrules.
8. Ferrules prevent spring terminals from slowly cutting through the cable strand by strand in vibration-prone environments.
9. Neat andamp; tidy, professional finish. Consistent connection point.
10. Ferrules are required in UK IEE Wiring Regulations on multi-stranded cables.
    
    

These charts compare the resistance of solid copper, stranded copper and ferruled connections :-

Charts taken from Weidmuller's White Paper "Ferrules: Your Best Insurance Against Costly Connection Failure"

How much will it cost ?

Adding ferrules to any job only costs a matter of pennies per connection. Time-wise,  the time taken to crimp the ferrule is often mitigated by the ease of inserting it into the terminal. At the very worst we would say it takes the same amount of time as not using ferrules and trying to do a neat job.

Tools, as ever, vary hugely depending on their quality. Top quality, professional, ferrule crimpers such as the Knipex ones pictured below can cost £ 200 or more. However, for DIY use, a reasonable set of crimpers can be had for £ 15 to £ 20. Add another £ 10 or so for a good selection of ferrules and you're away. 

If your cables have thick insulation (such as H07RNF), it's worth considering using un-insulated ferrules and adding heatshrink coloured for polarity.  This helps to prevent any confusion, as insulated ferrules are coloured according to size and may not fit over the cable insulation.

Further Information

Further Recommended Reading : Victron Energy's - Wiring Unlimited - an excellent free PDF book about electrical wiring of systems containing batteries, inverters, charger and inverter/chargers. 

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