Case Study

Convert’s stand-a-lone waterproof grommet solves Wipac’s lamp wiring challenge for British luxury sports car


In early 2015 Wipac - a world class design and manufacturing company specialising in high technology exterior LED lighting for the prestige automotive market – started work on a new lighting project for a British luxury sports car manufacturer.


The brief required Wipac to design a waterproof yet compact high performance LED lighting system with an external profile of between 3-5mm for the sealed connector which would house the wiring.


Vince Bailey, Wipac Head of Purchasing, said: “It’s standard industry practice that all lamp units for high performance LED lighting systems are waterproof.  Internal space constraints are also becoming a critical issue as demand increases for us to produce more complex lamps, with a high number of different internal elements, but not to increase the overall size of the finished lamp.”


Clearly, in order to provide a water-tight finished unit, the traditional methods of mounting 35mm electrical connectors onto the lamp housings would not be feasible due to their physical size. To find a solution, Wipac turned to Convert - their long standing electrical engineering company and one of the UK’s leading manufacturer of cable looms and harnesses.


“We’ve worked with Convert for seven years,” said Vince. “They provide cable harnesses for all our head and rear lights.  We knew we could trust Dave and the team to come up with an innovative design solution.”


To overcome this challenge, Convert’s team of engineers - which included Quality and Engineering Manager, Josh Boakes, who recently won a coveted Electronics Weekly Bright Sparks award - conceived a design with a grommet that would be integral to the cable harness for the lamp enclosure.  A second vehicle grommet was also required to protect the vehicles internal compartments from the potential water ingress.


However, a number of hurdles had to be overcome when sourcing the grommet.


Firstly, whilst it’s not unusual to use grommets for traditional filament bulb lamp enclosures, commercially available parts for these styles of lamps didn’t provide the required level of moisture projection.


Secondly, the high temperature cable required in LED lighting made this design even more demanding.


Dave Lord, Convert’s Managing Director, said:  “We started trials to find an automotive grade material that would be malleable enough to make final lamp assembly feasible and that would bond to the cable insulation to provide the waterproof seal.  However, we found the materials that bonded to the cable were too stiff to allow final assembly.  Similarly, softer materials wouldn’t create the required bond due to the special properties of the high temperature cable outer insulation jacket.”


“It soon became obvious that a new solution was needed to overcome this problem,” said Dave. “It was then we had our Eureka moment and developed the concept of the stand-a-lone grommet.”


This new style of grommet required cable tunnel guides of exactly the correct size to allow the cable to pass through the grommet. This created a waterproof seal once fixed to the cable harness, which in turn would be stable and secure when fitted to the finished lamp.


To produce the initial parts, Convert invested in a low volume mould machine and tooling.


“During 2015 the grommet dimensions were defined and we started to produce prototype parts,” said Dave.  “Through product testing the cable guide theory proved successful, however the assembly team on the car production line were finding the finished parts inconvenient to assemble into the car.  So after a further design review, we identified alternative design concepts for the vehicle grommet.    We re-designed the grommet and produced the prototype tooling for this new solution.  The re-designed grommet passed the required tests to meet the waterproofing standard IP66K to which Wipac works, meaning it was able to withstand water spray at 145PSI (Pounds per Square Inch) from 3 metres for a test duration of 2-3 minutes.   Thankfully all previous assembly line issues were resolved too!”


The new lighting project moved into pre-production in early 2016, and into volume production a few months later.





Convert’s stand-a-lone waterproof grommet is now also successfully used in Wipac’s lamps for both a British luxury car manufacturer and a British high performance sports car manufacturer.


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For more information on Wipac, visit:







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Rachel Price, Aro PR and Marketing                              t .01752 894 786      m. 07806321333


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