With the recent bad weather back east my email inbox has been filled with all sorts of questions regarding portable generators, transfer switch wiring, powering furnaces, well pumps etc. One of the big problems people are having is with the newer inverter type generators, the Honda EU series and the Yamaha and countless others like them. The issue is with powering certain equipment and electronics the generator shows a ground or reversed polarity fault and won’t work.
The problem is that these generators use what’s called a floating neutral or unbonded neutral/ground. Standard wiring in a home has the Ground and Neutral Bonded together usually at the Circuit breaker panel or distribution center.
So for example you have a (HE) High Efficiency Furnace that is wired through a transfer switch, using your Honda EU2000 generator won’t run it but you have an older Coleman generator and when you hook that up it works just fine.
The Honda EU2000 isn’t providing the Ground-Neutral Bond that your HE Furnace requires… to think it’s getting properly grounded power, while your Coleman generator has a Ground-Neutral bond already so it operates your HE Furnace properly.
Now sometimes this can be alleviated by making sure you have everything wired properly, sometimes simply not switching the neutral wiring in a transfer switch will accomplish this as well. Other times you simply have to create your own Neutral-Ground Bond. In the past Honda put out a Service bulletin on G-N Bonding and rewiring the generator head itself, and others have done this too but I don’t recommend it for one you’ll ruin your warranty and could cause other problems not to mention the risk of shock or fire.
The easiest way to do a N-G Bond is to create a N-G Bonded Edison Plug, this is done by simply buying a replacement male plug and wiring the Neutral (White Wire/Silver Screw) to the Ground (Green Wire/Green Screw) using a 12-14 Gauge piece of wire. Just make darn sure you don’t wire the Hot leg tot he ground. Then when you need to power something like a RV or HE Furnace with your generator you plug it into a empty outlet.
Make sure you label this plug specifically for its purpose. It won’t really do any harm to anything if it’s plugged into a correctly wired home outlet, but it will create a secondary G-N bonding point that could induce ground loop currents and create hum or buzz in a sound system.
I hope you found this information helpful, as with all electrical work be careful and sure of what your doing, and verify all information before attempting to rewire or override a safety device, and never remove the Ground Neutral Bond from a bonded generator.