E8: Missing neutral inside the RV

E8 means the Watchdog sees power going into your RV but not enough coming back on the neutral (white) wire. The problem is inside your RV, between the Watchdog and your main panel. The pedestal isn’t the cause, so you don’t need to call the park.

In our experience the cause is almost always a connection point: loose, corroded or burned. New RVs get this too. Connections are often not tightened to spec at the factory and loosen with travel.

Most common causes

Notice when the E8 happens. That usually points to the cause.

• Loose inlet: the twist-lock plug isn’t turned all the way. E8 shows almost right after hookup and keeps coming back.
• Burned inlet: a loose neutral sparked and burned the connection.
• Automatic transfer switch: worn or faulty contacts, even on switches under 4 years old. E8 when switching power sources, or almost constantly on shore power.
• Air conditioner wiring: factory or aftermarket connections not tightened enough. E8 when an AC turns on.
• Loose bus bar in the breaker panel.
• Inverter installed wrong, at the factory or aftermarket.
• Ground-neutral bond inside the RV. There should be none while on shore power. (A bond on a generator is required. See Using it with a generator.)
• Melted plug. See My plug melted.
• A failing appliance that draws a lot of power: AC, refrigerator, coffee maker, water heater, hair dryer. E8 when that appliance starts.
• Hardwired Watchdog installed after the transfer switch. It must go before it.
• Arcing inside the transfer switch as it switches.

Check it yourself first

1. Where your RV cord plugs into the Watchdog, check the socket for heat damage or shriveled rubber.
2. If your RV has an inlet: unplug the twist-lock. Check the plug and the inlet on the RV for discolored contacts or melted plastic. Plug it back in and twist it all the way until it locks.
3. If you have a cord reel instead, follow the cable to where it’s wired in next. This is often the transfer switch.
4. Still unplugged? Take the cover off the automatic transfer switch. Look for corrosion, discolored metal, heat marks or debris. Sniff for a burned smell.
5. Check the breaker panel for the same signs.

Find the circuit with the breaker test

The Watchdog app becomes a diagnostic tool here.

1. Put everything back together safely. Turn all breakers inside the RV off.
2. Plug in and open the live monitor in the app.
3. Turn on the main breaker(s). Watts should read near 0.
4. Turn on the top-left breaker. Wait 1 minute. Then the top-right. Wait 1 minute.
5. Keep going, left to right, top to bottom, waiting 1 minute each time. Watch the watts climb in the app.
6. If E8 appears right after a breaker, that circuit is the likely cause.

When to call a technician

Hire a certified RV electrical technician. RV wiring is different from house wiring, and RV techs see neutral problems often. A house electrician may treat an RV hookup like a 240-volt house circuit, and that mistake can badly damage an RV. If E8 happens when a certain AC turns on and you’re not comfortable on the roof, have a technician check it.

In rare cases the problem isn’t at a connection at all. We once traced an E8 to a nail driven through the neutral wire behind the bus bar.

Still stuck? Call us. We’ll walk through this same checklist with you.