The lost neutral (50A danger)

On a 50A coach, losing the neutral can put high voltage on some outlets and low on others. It can burn up electronics fast.

The short version

• Symptoms: lights getting bright and dim, appliances acting strange when loads change, burned electronics.
• Check voltage on each leg at the panel with loads running. A big difference between legs is a warning sign.
• Inspect the shore cord plug, the pedestal and the main panel neutral connections for heat damage.
• Treat it as urgent. Shut down 120V until it's fixed.

On the job

1. Lights bright in one room and dim in another on 50 A: unplug now.
2. Meter each leg to neutral at the panel: one high, one low, adding up to about 240 is the signature.
3. Check the neutral at the pedestal, the plug and inlet blades, the transfer switch, the panel neutral bar.
4. Fix the open and replace what burned. Recommend an EMS with open-neutral protection.

Shop tip

Check the shore cord plug blades for heat discoloration. Loose plugs cause a lot of these.

Try it on a service call

Put the lesson to work on a hands-on troubleshooting case.

• Lights surge and the microwave died

Keep going on 120V and shore power

Learn it

• Shore power: 30A vs 50A
• Breakers, GFCIs and the EMS
• Transfer switches and generator power

Prove it

• Half the coach is dead
• Bathroom outlets are dead
• Lights surge and the microwave died
• Shocked at the door handle

On the job

• 120V system
• 50A power problems