Learning, Wiring,

What are the 3 Wires on a Microwave Transformer? (Tutorial)

One important component of a microwave is the microwave transformer. Without it, your microwave will not work. The transformer has three wires that make the functioning of the electronic seamless. What are these wires and what are they called? What do they do and how do you wire one?

In this article, we explain what the 3 wires on a microwave transformer are. We will also go a step further and tell you how to wire one.

The 3 wires on a microwave transformer are referred to as the three windings. The first and second wires are for heating magnetron filament, which generates a low voltage output. The third wire is for the ground connection and has a high voltage.

three windings
Video | potatogun96

What are the 3 Wires on a Microwave Transformer Called?

The 3 wires on a microwave transformer are referred to as the three windings. The primary windings get 120V or 240V main voltage while the second is high in the power circuit. The third wire has a lethal volume of current and it is for the ground connection.

It is crucial not to tamper with the third wire because of the high voltage it carries. If you are not experienced in electrical work, you should be careful about messing around with a microwave transformer. Only well-experienced people in electricity should experiment with the microwave circuit.

What Do the 3 Wires on a Microwave Transformer Do?

The side of the microwave transformer with the three wires is the secondary output. The first and second wires are for heating magnetron filament, which is a low voltage output. The third wire is the high voltage connection and the other end of the wire is connected to the iron core.

This is grounded, which gives a high potential between the third wire and the core. You should be careful when dealing with microwave transformers because they can produce a current as high as 500 mA and at 2 kV, it can be very lethal when grounded. However, if it is grounded, you do not have to worry about getting shocked when you touch it.

How to Wire a Microwave Transformer

The first thing to emphasize here is that wiring a microwave transformer with three wires is not recommended for inexperienced people. You should know what you are doing before you embark on wiring one because of the high voltage.

wiring microwave transformer
Video | potatogun96

The items you need include a microwave oven transformer, a 3-pronged power cord, a pipe, wires to connect everything, and a couple of bolts.

Follow the steps below to wire a microwave transformer:

Step 1: Get a power cord and strip it bare to expose the neutral and live wires in it. Note that this does not have any polarity since it is not an alternating current. Use plenty of solders to solder the wires carefully to the AC input terminals. The reason for recommending tons of solder is because of the high currents.

use ballast to curb the current
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Step 2: Next, use a ballast to curb the current as you complete the mains wiring. The ballast can be anything that functions on wall power. Next, it is time to draw an arc from the voltage. Note that the high voltage will come from a single terminal on your microwave transformer.

Also, note that the ground is the outer casing of the transformer. However, you should not hold the naked wire with your bare hand. Get a safety stick made with a non-conductive material and draw the arc.

draw arc with safety stick
Video | potatogun96

Make sure you do not put any flammable material close to the arc. That is because the arc gets hot as you apply pressure and will set fire to any flammable material around it. (1)

Step 3: If you need more power, trust that you can get it. Generally, the microwave transformer can trip the breaker at a 15 amp microwave circuit. This is typically the standard for most homes in the US. Of course, some homes use a 20-amp circuit breaker.

Whatever the case, if you need more power to run the un-ballasted microwave transformer, you have the option to use clothe dryer receptacle. Clothe dryer receptacle is of two types – the NEMA 10-30 and the NEMA 14-30.

They are both center-tapped outlets, which means they have two hot leads and one neutral and can give 120V or 240V. Note that NEMA 14-30 is more contemporary, but they both deliver a maximum of 7200wats, which is 240V at 30-amp.

You should know the outlet’s wiring before you wire the microwave transformer. You need a power cord for the receptacle and a multi-meter for the continuity setting.

Wrapping Up

As mentioned, you need the experience to work on a microwave oven. If you are not well-versed with wiring, you should not try to wire a microwave transformer because of the high voltage. (2)

Take a look at some of our related articles below.

(1) flammable material – https://www.sciencedirect.com/topics/materials-science/flammable-material
(2) microwave – https://home.howstuffworks.com/microwave1.htm

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About Sam Orlovsky

AvatarCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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