Guide to Spade Extensions
Improve the installation flexibility and lug capacity of your transformer using spade extensions.
June 20, 2025
Parts
Imagine this: Your old transformer has been removed, and your brand new one is delivered and put in place. You walk up to the new transformer ready to hook it up.
But then you realize…there’s a problem.
The old cables are too short to connect to the unit. There’s no way the cables can reach the transformer bushings. Or, you discover that the existing spades have ten holes when you need fourteen. You can’t hook up the transformer until you find a solution.
Sound familiar?
It’s common to have issues around connecting transformer bushings with incoming and outgoing cables. Typically, the cables are too short, or the current bushings don’t have enough lug capacity.
If you’re dealing with either of these problems, you may want to consider spade extensions. Spade extensions are a simple solution for increasing lug capacity and extending cable connections.
Let’s review what spade extensions are, how they can help, and common questions people have.
What is a spade extension?
A spade extension is a tin-plated metal adapter designed to attach to transformer terminals. Typically, technicians bolt the extensions onto the current spade terminals or bushings. Spade extensions can come in all shapes and sizes. Check out an example of a twelve-hole spade below.

When should you use a spade extension?
If your transformer bushings need more lug capacity than they currently have (ten holes vs. fourteen holes), you only have a handful of options. You can either ship the unit to a shop to have the bushings replaced, or you could complete the repairs yourself. That would involve powering down the unit, draining it, unbolting the existing bushings, reinstalling new bushings, refilling the unit with oil…you get the idea. A lot of time. A lot of money. Not fun.
Additionally, if your cables are too short to reach the bushings, there’s the long and painful process of splicing new cables. Most of us would rather have a tooth pulled without painkillers.
Let’s take a look at how spade extensions can help you in both of these situations.
If You Need Additional Lug Capacity
If you order a transformer with six-hole spades, but actually need twelve-hole spades, spade extensions are the ideal solution.

Rather than spend the time and money to switch out the bushings, you can simply add an extension to ensure the spades have the lug capacity you need.

If Your Cables Are Too Short
If you ordered a transformer to replace an old unit, but the new bushings are higher than the original, you may need spade extensions.

These will enable you to connect the original cables to the new transformer without any changes to the cables’s length.

Common questions about spade extensions
Lastly, let’s look at a few common questions customers have about spade extensions.
Will I need secondary supports?
If your transformer already has bushing supports in place, those should be enough to support the new spade extensions. However, if the spade extensions you’re adding are particularly heavy, you may consider adding secondary supports to properly carry the new weight.
Can I use aluminum and copper lugs?
The majority of spade extensions use tin-plated copper which works well with both aluminum and copper lugs. However, make sure you always verify the ratings and the material of each spade extension you use.
Conclusion
Spade extensions are a simple addition to your transformer that give you more installation flexibility.
For any other questions about transformer components, fill out the form below. We would love to help you power on your next project.