Hi,
How can I safely connect a portable generator to supply power to a house?
The house has a standby generator which no longer works, and the stator and rotor windings are completely shorted.
I lease the house and thought a portable generator would be a more affordable solution.
The standby system is connected to house power through an automatic transfer switch. I was told by a generator service person (after he looked at the type of switch) that I could still use this as a transfer switch.
I thought that I could have an electrician put a junction box with a 50A outlet on the metal case housing the nonfunctional standby generator (where the buried power cables connecting to it surface). And then I could take a short RV cable and connect to the 50A outlet on the portable generator. However, an electrician came out and send no -- no temporaries.
His solution is to permanently install a cable (with a male end) to where the power is coming out of the house (from the transfer switch located in the mechanical room) which connected to the now defunct generator. He told me that I could wrap the cable around a stand for a water hose.
I don't like the idea of having this permanently heavy connected cable with a plug -- besides inconvenient -- it is connected to building power through the transfer switch -- which seems like a potential electric shock hazard to me.
A would appreciate any advice. We need a generator because we live in an area that is frequently out of power and the outages can last for days. (I plan to connect the generator to a large propane tank which served the non-working generator.)
The safest way to connect a generator is to follow the NEC requirements. Have you considered replacing the existing generator?
For a portable, you will need a manual transfer switch. The existing automatic switch wasn't designed to be used as a manual switch, and should be replaced with the proper equipment. The type of manual switch will depend on what type of portable generator you have. If the generator is floating neutral you will need to install a manual transfer switch with a solid neutral connection to the utility neutral. If the generator is a bonded neutral, the manual switch will have to switch the neutral conductor upon transfer and the portable generator will have to grounded as a separately derived system. See 702.11, 250.30, and 250.34
The power inlet box has to labeled in accordance with 702.7(C) Please note that flexible cords are not permitted to serve as a substitute for the fixed wiring within a structure. The wiring from the power inlet box to the manual transfer switch has to be installed in accordance with Chapter 3 of the NEC. The NEC does permit a cord to serve as the temporary connection from a portable generator to the power inlet box.
The ICC IFGC (International Fuel Gas Code) in Section 301.3 requires any appliance, generators included, that connect to a fuel gas piping system to be listed and labeled. The NFPA 54, National Fuel Gas Code in Section 9.1.1.3 allows the acceptance of unlisted appliances, equipment, and accessories on the basis of a sound engineering evaluation. Please be aware that many of the portable generators available are unlisted generators. This means that the generators cannot be connected to a fixed fuel piping system, LP or NG.