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nJoin Power Module (USG-4000)

nJoin Power Module (USG-4000)

The nJoin is an intuitive Power Module with built-in GFCI for large electric floor heating applications. The nSpire Touch, nSpire Touch Wifi, nHance and nTrust thermostats can be extended with additional nJoin power modules. Output can be increased by 15 A per nJoin module.
This support page provides publications, manuals, videos, support articles, and common support questions for the nJoin Power Module product line.

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Support Questions

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A GFCI/GFEP (Ground Fault Circuit Interrupter / Ground Fault Equipment Protection) works differently than a circuit breaker by specifically detecting a small imbalance in electrical current between the hot and neutral wires, which indicates a potential ground fault (like a person touching a live wire), and instantly shutting off the power to prevent shock, while a circuit breaker only trips when there's a significant overload in current flow on the circuit, like a short circuit or too many appliances plugged in.

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Pressing and holding (2-3 sec) physical power/reset button will turn the unit completely OFF. Same process turns the unit back on.

(nHance and nJoin units will have the button on the front faceplate, nSpire Touch WiFi, nSpire Touch and nTrust will have the button on the right side of the faceplate.)

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Relays can fail due to excessive current or voltage. When a relay is exposed to too much current, the contacts can burn out. High voltage can also damage the coil. Other reasons include mechanical wear and tear, dust or dirt buildup, and moisture. These factors can cause the relay to malfunction or stop working entirely. Regular maintenance and using the relay within its specified limits can help prevent failures.

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Check the connections between the thermostat and power module. If the power module is connected incorrectly to the thermostat, the power module won't switch off.

USG Power Module Connection Diagram


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No. The nJoin power module is not compatible with a Honeywell system.

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This indicates a fault, current to ground. The thermostat has cut off the power for your safety. Please contact your local electrician or WarmlyYours Technical Support.

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GFCI can fail for various reasons, such as wear and tear, moisture, corrosion, power surges, faulty wiring, or improper installation. Some of these causes can be prevented by regular inspection and maintenance, while others may require professional assistance. It is important to note that GFCI devices (ex. thermostat, breakers, outlets) should be tested regularly as these do wear out over time.

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