You’re making these mistakes in your cable assembly design


In a single year, we ship hundreds of thousands of custom cable assemblies. When you design and build that many products, a few themes start to emerge — including some oft-repeated design mistakes.

These errors are seemingly simple. But if they aren’t addressed, they can lead to a design that looks good on paper but doesn’t completely translate to production.

We don’t expect you and your engineering team to catch these small missteps, especially when cable assemblies are just one of many components on your plate. That’s where the expertise of a cable manufacturer comes in: To optimize the design and remedy common errors.

In this article, we’ll share five common design mistakes and industry-proven advice for fixing them.

(And for more guidance on how to approach cable manufacturability, read this article.)

Five common design oversights — and how to fix them

1. Overengineering multi-conductor cables

There is a massive amount of variety in the market when it comes to possible multi-conductor cable solutions. From temperature ratings to flex ratings, shielding options and outer jacket materials, it can be difficult for your engineering team to know exactly what they’re looking for — and what they don’t need.

Or we often see designs where a part number is simply recycled from one assembly to another, usually due to in-house prototypes being built with the same on-hand materials.

Either way, this can result in significantly overly specified multi-conductor cable — which then becomes a massive cost driver.

Solution: A highly rated multi-conductor cable, if it isn’t critical to your design and its intended function, can be replaced with a standard version.

2. Mismatch of wire AWG to terminal size

Terminals are compatible with certain wire gauges (such as AWG 16-18 or AWG 18-22). Make sure they match up, and you’re usually good to proceed.

However, we’ll sometimes come across a design where the terminal and wire, while technically within the appropriate range, don’t actually fit.

This is due to incompatible insulation size. For example, if you specify UL 1015 wire, this comes with a larger voltage rating — and thus a larger insulation diameter. The wire may be on the larger side of the gauge range of the terminal, but that additional thickness in the insulation diameter can actually put that UL 1015 wire out of spec for that terminal. The gauge looks compatible on paper, but not in practice.

Solution: Things are not always as they seem when they come to wire gauge ratings. Ask your cable assembly partner to double check your wire and terminal pairings to make sure there’s no size incompatibility due to insulation or other diameter changes.

3. Unnecessarily precise dimensions and tolerances

As dimensions get smaller, wire-cutting machines have to reduce speed, precision must increase, assemblers doing heat shrinks or labels will spend more time applying — overall, efficiency is reduced.

These precise dimensions can be accommodated, but it’s important to consider the extra time and effort and weigh it against the value the tolerance provides.

Further, dimensions at odd intervals can also make an assembly more costly. Easily understood fractions such as ½ inch or ¼ inch are safe bets. Not everyone is going to know the decimal conversion for 5/32 inch off the top of their head, thus slowing down your production rate.

Solution: If you do need precise tolerances, a good rule of thumb is the larger, the better. And stick to round, simply measurable dimensions. 1/8 inch is probably the smallest that can be easily accommodated without more involved calibration of tooling options, especially at very short lengths. If an incredibly precise measurement isn’t necessary, however, it’s best to avoid it for the sake of production efficiency.

4. Calling out a specific wire manufacturer when a standard will do…

Including a specific part number from a specific manufacturer, while seemingly helpful in a design, can actually make production more complicated.

If it is not a standard-rated wire, it can lead to supply issues and put your production deadline at risk. Or the item might not be available at high volumes and thus have a large minimum order quantity that you didn’t expect.

Solution: On the whole, a very specific material request isn’t always a design mistake — more so a potential red flag that can lead to the aforementioned supply issues. If it truly is a must-have part for your design, keep it as is. But if it can be replaced with a more standard part, do it. Start with a wide pool of materials and narrow it down with the basics: Voltage, temperature, flexibility and gauge requirements.

For hook-up wire selection, we steer customers to one of three different UL wire types:

  • UL 1061 – The thinnest insulation, rated to 300V and 80 degrees Celsius
  • UL 1569 – Medium insulation thickness, rated to 300V and 105 degrees Celsius
  • UL 1015 – The thickest insulation, rated to 600V and 105 degrees Celsius

5. …or vague descriptions

On the other hand, designs that simply note “use wire as required” won’t adequately tell your cable manufacturer what you’re trying to accomplish. This makes it difficult to achieve a cable assembly design that best serves your performance demands and works within your production timeline.

Solution: Any info is better than none. Once again, starting with the basics (voltage, temperature, flexibility and gauge) will put you and your manufacturer in a better position to achieve a cable assembly design that works for your needs.

Has a cable assembly expert seen your design?

You’ve already made great progress on your custom cable assembly.

But like any product design, a second set of eyes can make a huge difference.

At Multi-Tek, our cross-disciplined teams are able to identify and resolve design problems before they have a chance to impact your end product. We’ll work together to catch inconsistencies, make recommendations for material swaps and ensure an efficient manufacturing process. Let’s talk cable assembly solutions.