Chapter Eight - Shore Power

Even if you have installed an effective renewable power system on your bus or truck, there will be times when you will want to connect to utility power when it is available to conserve battery power or run appliances which draw too much current for your batteries to support. The nautical term for this connection is 'Shore Power'. Utility power will allow you to operate space and water heating appliances, recharge your batteries if needed, and live life in the 'normal' consumptive manner.

While connecting to a convenient electrical power receptacle seems simple enough, be sure that you plan ahead for this in the design and construction of the electrical system on your rolling home. Your AC power system can be as simple as several 'plug strips' connected to an extension cord, or be a complex multi-branch circuit load center with circuit breakers for individual appliances. In any event, you will want your installed system to be safe, and conform to any applicable electrical building codes you may encounter.

Foremost in your consideration should be making sure that the frame of the vehicle, and all exposed metal parts, etc are properly grounded while the AC power is connected. Any fault current that finds it's way to the vehicle's frame, by whatever path, will turn the entire metal structure of your truck or bus into an electrocution hazard. Normally, this grounding connection is accomplished by the grounding conductor integral to the connector and cord that connects the system to the utility grid power. Be sure that this part of the circuit is installed properly and is in working order before connecting to any utility power source! Also confirm that the grounding conductor of the receptacle that you are connecting to is properly grounded. A variety of inexpensive indicating instruments are available that can identify faulty wiring or connections, and you should invest in one and use it before connecting your valuable mobile habitation to an unfamiliar power source.

Also very important is the installation of appropriately-sized fuses or circuit breaker devices. These over-current protection devices will prevent your system from overloading the wiring supplying the utility power to your vehicle, and protect your equipment from short-circuit currents. Additionally, you will find it easier to reset an over-current device that trips inside your bus after an accidental overload, than to try to find and access the protective device at the supply end, which may be enclosed inside a locked circuit breaker panel, or be difficult to locate in an unfamiliar (and possibly now very dark) building. It's also good politics to not blow your host's fuses!

If your housetruck includes an inverter or generator, you will need a method of switching between on-board power and shore power. This can be as simple as having the cordset which powers the system plug into the generator, inverter, or utility outlet, as needed. Any manner of transfer switching devices can be installed to make the connection either manually or automatically. It is essential that the inverter and/or generator not be "back-fed" utility power into their output terminals, so be sure that your vehicle's power system is wired properly to prevent this when using shore power.

It is sometimes helpful to have an AC voltmeter which can be used to read the utility power's voltage before connecting, particularly if you may encounter non-standard voltages or receptacle configurations. Finding out too late that you connected your 120 volt system to a 240 volt outlet is sure to be more than mildly disappointing, and possibly very exciting as well

Finally, be sure that any receptacle that you connect to is capable of supplying an adequate amount of current, equal to, or exceeding what your vehicle's system will consume. Also make sure that your cordset, or any extension cords you use to connect are of a sufficiently heavy gauge to carry the expected current.

Of course, it goes without saying that you will be careful when using all forms of electrical power, and observe all prudent and proper precautions, leading to personal and property safety.