Best isolation transformer

Charging & Power

In addition to creating the eponymous Faraday cage, Michael Faraday created the first-ever working dynamo and discovered the chemical compound known as benzine.

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Which isolation transformers are best?

As anyone who has engaged in electrical engineering can attest, potential shocks between the conductor and the ground could cause damage to sensitive circuitry and cause serious injuries. Whether you are interested in testing isolated circuits, eliminating interference, or providing safe and reliable power, an isolation transformer is a great thing to have. With a dependable and robust unit like the Tripp Lite IS250 Isolation Transformer 250W Surge 120V 2 Outlet at your disposal, you can test and even shield electronics to your heart’s content.

What to know before you buy an isolation transformer

Used across industries

Just like the transformers used to transmit electricity through power lines, isolation transformers contain a pair of powerful electromagnets which have been equally interwoven through each other so that the first coil will induce an electrical current in the second coil. Also referred to as a 1:1 transformer, isolation transformers prevent any electrical hazards from occurring that involve a neutral wire in an outlet connected directly to the ground. Failing to use an isolation transformer when engaged in electrical testing coils could cause serious electrical injury. Investing in an isolation transformer is a much safer option. 

Shielding sensitive tech from noise

The more delicate a particular piece of electronic equipment is, the more at risk it is from interference caused by other nearby devices. There are two main forms of interference, namely electromagnetic interference (EMI) and radio frequency interference (RFI).

Thankfully, the use of isolation transformers can eliminate sources of outside interference. This allows you to either continue operations without interruption or systematically eliminate sources of interference. Types of sensitive electronic equipment that could benefit from being shielded include medical devices such as pulse monitors, laboratory instrumentation, process controls, computer-aided design and manufacturing (CAD/CAM), sensors for scientific study, testing of consumer and industrial electronics, among others.

Power requirements

Because electrocution is such a high risk, you should also purchase an isolation transformer that produces sufficient voltage to meet your needs. Other points of consideration include whether your project or testing isolation transformer could benefit from having the ability to plug in more than one device simultaneously and easy installation in a wall mount or tower setup. 

What to look for in a quality isolation transformer

Certified by professional organizations

The Federal Trade Agreements Act (TAA) for GSA Schedule purchases involves a set of legal requirements that businesses that operate under a federal contract must follow. These businesses are allowed to sell products or services to the U.S. government through the General Service Administration (GSA). All businesses that operate under such contracts are legally required to ensure that any “final products” sold under your GSA contract are not manufactured in specific countries. These countries include (but are not limited to) China, India, Indonesia, Iran, Iraq, Malaysia, Pakistan, Russia, and Sri Lanka. As such, make sure you look for a product’s TAA/GSA compliance to ensure you are following government regulations when manufacturing or reselling.

Protection from shocks or injury

Attempting to separate a unit’s AC power cord from its metal chassis can result in shocks and injury if you’re not careful. Thankfully, an isolation transform completely removes the risk of accidental electrical shock by safely grounding the AC. This allows you to safely diagnose and fiddle with components to your heart’s content.

Built-in Faraday cage

Faraday cages are specially designed enclosures that prevent any interference from outside electromagnetic fields. While creating a Faraday cage could involve anything from layers of copper screening to a full-blown metal cage, isolation transformers have a Faraday cage built-in. This prevents the current flow from being interrupted by electrical fields and lessens the impact of EMI on the signal line. These benefits can help keep your delicate electronics correctly calibrated. They improve electronics’ efficiency and power quality by reducing the potential for current leakage.

How much you can expect to spend on an isolation transformer

Depending on your desired features and budget, a quality isolation transformer usually costs anywhere from $110-$240.

Isolation transformer FAQ

Do I really need to buy an isolation transformer?

A. Absolutely. Not only is it the only way to ensure accurate readings from sensitive equipment, but an isolation transformer helps to protect people, equipment, and circuits from hazards like short circuits and shocks.

Can I still be shocked if I use an isolation transformer?

A. While touching both coils of a live isolation transformer with your bare skin could lead to a potentially fatal electric shock, you can touch a single live conductor without any inherent risk.

What’s the best isolation transformer to buy?

Top isolation transformer

Tripp Lite IS250 Isolation Transformer 250W Surge 120V 2 Outlet

Tripp Lite IS250 Isolation Transformer 250W Surge 120V 2 Outlet

What you need to know: This is a well-designed and reliable isolation transformer for all your sensitive electronics needs.

What you’ll love: This unit features total noise filtering, line isolation, and surge suppression. It is ideal for sensitive equipment. It contains two widely spaced NEMA5-15R output receptacles, a 6-foot power cord, a lighted power switch, and circuit breaker overload protection. It is also compliant with the Federal Trade Agreements Act (TAA) for GSA Schedule purchases.

What you should consider: Users have reported issues with the unit doing little to reduce interference from nearby ground loops.

Where to buy: Sold by Amazon

Top isolation transformer for the money

Jameco Valuepro GRP-1200 Transformer

Jameco Valuepro GRP-1200 Transformer

What you need to know: This affordable isolation transformer is ideal for electrical hobbyists or small-scale electrical testing. 

What you’ll love: This unit comes with lots of great elements for an amazing price. It includes an AC power cord, a 14-amp input and 7-amp output fuse for the transformer, two outlets for the isolation transformer output (which work with the switch and 7-amp fuse), two protected outlets (which feed the input of the transformer), and both a direct and isolated fuse.

What you should consider: Users have reported issues with isolated plugs being bonded to the ground, requiring clipping to achieve full isolation. 

Where to buy: Sold by Amazon

Worth checking out

Tripp Lite IS1000 Isolation Transformer

Tripp Lite IS1000 Isolation Transformer

What you need to know: This isolation transformer is ideal for protecting telecom, point-of-sale and diagnostic equipment from outside interference.

What you’ll love: This unit has a 1000-watt capacity capable of handling a variety of electronic devices, an integrated 9-amp circuit breaker, a 680-joule surge suppression rating, continuous transformer filtering, no wearable parts, and robust line noise filtering to prevent interference from EMI and RFI.

What you should consider: Users have reported issues with the unit causing more noise than it eliminates as well as line noise problems

Where to buy: Sold by Amazon


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Daniel Martin writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.

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