Safety and PPE Items are Available

Order Now

Reliance Controls MB75 Installation - PartsXP

reliance controls mb75 installation

Reliance Controls MB75 is ideal for use with any 125 or 250 VAC installation where balancing the load of an auxiliary power source (generator) is necessary for optimum performance. It is perfect for monitoring the generator load when your transfer switch or panel does not have meters. If you don't know how to install Reliance Controls MB75 wattmeter box, you can read this post. Here, we have listed out the Reliance MB75 installation instructions to make your job easier.

Reliance Controls MB75 Installation

Reliance Controls wattmeter box is designed to give you an accurate reading of how much you are using the generator's power. When you are attempting to figure out the generator's fuel efficiency or when trying to balance the load on the generator, you can know how much power you are using. However, here, we have given the Reliance Controls MB75 installation process to help you. Check out now.

Buy Reliance Controls MB75 Wattmeter Box at Low Cost!

Cautionary Notes

  • You have to be done the Reliance Controls wattmeter box installation according to the National Electrical Code and all applicable local codes.
  • You should not install or use this wattmeter in such a manner that exposes to voltage, current, or power levels. Make sure to follow the readings given in the box. So, to avoid hazardous operating conditions you must follow the listed absolute maxima level.
  • MB75 is built to be used on 125/ 250 VAC, 60Hz power circuits. If you connect this to other voltage and current circuits, it will give an unacceptable measurement error.
  • Make sure to install Reliance MB75 in a location where the ambient air temperature does not exceed 40 degrees centigrade or 104 degrees Fahrenheit.
  • Do not use the product with the wiring compartment cover missing or removed.
  • The installer is responsible for providing the appropriate sized conductors and overcurrent protection for wiring leading to and from the wattmeter box.

How to Install a Watt Meter on a Generator?

  • Open the watt meter box door and remove the mechanism.
  • To remove the mechanism, first, you have to remove the screw at bottom of the front plate.
  • After that, pull the wiring compartment cover forward with a tool like a screwdriver and pull it down to remove.
  • Now, loosen the screw at the top center of the front panel, tip mechanism forward, and lift out. The screw is clamped by the plate and it should not be fall out.
  • By using the holed provided, you need to mount the wattmeter box to the wall.
  • Replacing the mechanism in the enclosure is a simple task. Set the mechanism on the tabs and tip it backward to accomplish this. Tighten the holding screw at the top center of the front panel to secure it into the cabinet.

Shop for OEM Reliance Controls Wattmeter Box @ PartsXP.

Wiring Instructions

  • Connect one of the hot legs from the generator to terminal 1-front.
  • Wire other generator's hot leg to rear terminal 1.
  • Connect the white neutral wire from the generator to the neutral connection point of the transfer switch. Make sure there is no connection point in the meter box.
  • You need to connect the green ground wire from the generator to the green ground screw in the cabinet bottom.
  • Connect a wire from 3 terminal front to one of the appropriate hot leg connections at the transfer switch or panel.
  • You have to connect a wire from terminal 3 rear end to the other hot leg connection at the transfer switch.
  • Attach a green ground wire from the green ground screw in the cabinet bottom to the ground connection point at the transfer switch or panel.
  • When wiring is completed, you should replace the wiring compartment cover and retaining screw.

The internal jumpers need to be removed and the current transformers dropped down into the wiring compartment. These are already connected with the meters. You have to connect one of the two hot legs from your generator to the transfer switch through the hole or gap in one of the current transformers. Another leg of the generator needs to be connected to the other current transformer through the opening. You can follow this wiring method if bypassing the terminal bock is preferred.

Reliance Controls MB75 Wattmeter Available Here – Order Now!

Reliance Controls MB75 Operation

The internal meter box wiring consists of a jumper which is inserted through a current transformer in between the leg front and right front terminals. The current flowing through this jumper will display on the left meter. Similarly, you can see the reading of current flowing between the left rear and right rear terminal on the right meter. 


Hope this Reliance Controls MB75 wattmeter box installation guide helped you more. If you have to know in-depth details on Reliance MB75 installation, you can refer to the company’s manual. Stay tuned to PartsXP to get more guides on Reliance Controls products installation. PartsXP offers Reliance MB75 wattmeter boxes. So, you can purchase from here if you need.

About the Author

partsxp logo authorHaritha

Haritha is a Content Writer at PartsXP. She has a great understanding of today's marketing strategies that yield strong results and always happy to create valuable content & share her thoughts.

She was good at writing content for E-Commerce websites related to Electrical Parts, Appliance Parts, Food Service Parts, HVAC Parts, etc.

You can see some her contributions at,,