After more than two decades in HVAC service, installation, and troubleshooting, I can tell you one thing with absolute certainty: very few components confuse homeowners and junior technicians more than electric heat strips. The confusion almost always leads back to one issue—misunderstanding the electric heat strip wiring diagram.
Whether you are diagnosing a system that is not producing enough heat, installing a new air handler, or trying to understand why breakers keep tripping, the heat strip wiring diagram is your roadmap. When you understand it, electric furnaces make perfect sense. When you do not, even a simple issue can feel overwhelming.
In this article, I am going to walk you through electric heat strip wiring using the Goodman MBVK electric furnace as the primary example. The MBVK is an excellent teaching platform because it represents how modern electric furnaces are engineered: straightforward, modular, and designed with safety at the forefront.
What Electric Heat Strips Actually Do in a Furnace
Before we ever touch a wiring diagram, we need to talk about function. Electric heat strips are not “backup heaters” in an electric furnace—they are the heater.
Unlike gas or oil furnaces that rely on combustion, electric furnaces like the Goodman MBVK use resistance heating. When voltage is applied to the heating elements, they heat up, and the blower pushes air across those elements and into the duct system.
The amount of heat produced depends on:
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The number of heat strips installed
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The kilowatt rating of each strip
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How the sequencer or control board stages them on and off
Every one of those factors is represented in the electric heat strip wiring diagram, which is why understanding that diagram matters so much.
Why Heat Strip Wiring Diagrams Matter More Than You Think
I have been on countless service calls where the problem was not a failed component, but a misunderstanding of the wiring layout. Electric furnaces operate at high amperage. One incorrect assumption can lead to:
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Burned sequencers
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Tripped breakers
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Melted wiring
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Premature element failure
A heat strip wiring diagram shows you:
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How power enters the system
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How it is distributed across heating elements
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Where safety devices interrupt the circuit
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How staging prevents overload
Goodman does a solid job making these diagrams readable, which is one reason I often recommend the MBVK platform for both residential and manufactured housing applications.
Overview of the Goodman MBVK Electric Furnace Design
The Goodman MBVK electric furnace is designed as a modular air handler with optional electric heat kits. This means the furnace cabinet remains consistent, while the heat output is customized by installing the appropriate strip kit.
From a wiring perspective, this modular design simplifies troubleshooting. Instead of dealing with a maze of factory-installed elements, you can isolate each heat kit as its own circuit group.
According to Goodman’s own technical literature, electric furnaces like the MBVK follow industry-standard wiring logic, which aligns closely with diagrams published by organizations such as the Air Conditioning Contractors of America, a widely respected authority on HVAC system design and standards.
Breaking Down an Electric Heat Strip Wiring Diagram
Let’s talk through what you will see on a typical electric heat strip wiring diagram for the Goodman MBVK.
1. Line Voltage Supply
Electric heat strips operate on line voltage—typically 240 volts in residential applications. The wiring diagram will show:
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L1 and L2 incoming power
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Circuit breaker or disconnect upstream
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Distribution points inside the air handler
This is where many mistakes happen. Each heat strip bank draws a significant amount of current, which is why proper breaker sizing is critical.
2. Sequencers or Electronic Controls
Traditional electric furnaces use heat sequencers—electromechanical devices that stage the heating elements on a delay. Modern MBVK configurations may use integrated control boards that perform the same function electronically.
In the wiring diagram, the sequencer is the traffic cop. It prevents all heat strips from energizing at once, which protects both the electrical system and the furnace components.
If you have ever wondered why heat seems to “ramp up” instead of hitting full blast instantly, the sequencer wiring explains exactly why.
Understanding Safety Circuits in Heat Strip Wiring
One thing I appreciate about the Goodman MBVK design is how clearly safety devices are represented in the diagram.
Every electric heat strip circuit includes:
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High-limit switches
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Thermal cutoffs
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Sometimes fusible links
These components are wired in series with the heating elements. If airflow is restricted or temperatures rise too high, the circuit opens and shuts the heat down.
This wiring logic mirrors safety standards outlined by organizations like the U.S. Consumer Product Safety Commission, which emphasizes overheat protection in residential heating equipment.
If your electric furnace runs but does not heat, the wiring diagram will usually lead you directly to the open safety device.
How Staging Works in the Goodman MBVK
Electric furnaces rarely energize all heat strips at once. Instead, they stage heat based on demand.
In the electric heat strip wiring diagram, staging is shown by:
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Separate contact points for each heat bank
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Control voltage wiring from the thermostat
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Sequencer timing paths
For example:
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First stage energizes one heat strip bank
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Second stage energizes an additional bank
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Emergency heat may energize all banks simultaneously
Understanding this wiring helps explain common homeowner complaints like uneven heat or high electric bills.
Common Wiring Mistakes I See in the Field
After years in the field, I can tell you the same mistakes show up again and again:
Misreading the Diagram
Some people treat the diagram like a suggestion instead of a map. Every line matters.
Improper Wire Gauge
Heat strips draw heavy amperage. Undersized wiring leads to overheating and nuisance trips.
Bypassing Safety Devices
I cannot stress this enough: never bypass a limit switch. The wiring diagram clearly shows their role for a reason.
Technical training resources from platforms like HVAC Excellence consistently emphasize diagram literacy as a core safety skill for technicians.
Diagnosing Problems Using the Wiring Diagram
One of the biggest advantages of understanding a heat strip wiring diagram is faster diagnosis.
If the furnace:
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Blows air but no heat → Check sequencer and limit circuit
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Trips breakers → Check element resistance and staging
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Produces partial heat → Check which strip banks are energizing
With the Goodman MBVK, each heat kit can be isolated and tested individually, making troubleshooting far more efficient than older all-in-one electric furnaces.
Why Electric Furnaces Like the MBVK Are Still Relevant
There is a misconception that electric furnaces are outdated. In reality, they are often the best solution for:
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All-electric homes
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Manufactured housing
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Regions without natural gas
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Pairing with heat pumps
When installed and wired correctly, systems like the Goodman MBVK are reliable, safe, and predictable. The wiring diagram is what ensures that predictability.
Energy efficiency guidance published by the U.S. Department of Energy continues to recognize electric resistance heat as a viable option when applied correctly and paired with proper controls.
Final Thoughts From the Field
If there is one takeaway from this article, it is this: the electric heat strip wiring diagram is not optional knowledge. It is foundational.
The Goodman MBVK electric furnace provides a clear, modern example of how electric heat should be wired, staged, and protected. When you understand the diagram, you understand the furnace. When you understand the furnace, you can install it safely, service it confidently, and explain it clearly to homeowners.
Electric furnaces may not have flames or burners, but they demand just as much respect. High voltage does not forgive shortcuts, and the wiring diagram exists to keep both people and equipment safe.
As I tell every new technician I train: before you pick up a meter, pick up the diagram.
