Convection oven shock

[whodoc]

Wife just got shocked while reaching into the Micro/convection oven and bumping the oven hood with her arms. I tried the same thing and nothing happened. I then used a voltmeter, touching inside the door with red and grounding on the oven hood,, read 114
I then unplugged the Micro and get zero reading.
Will be calling the factory tomorrow..
we are In Yellowstone now and traveling east..... will need to find repair in Montana, North Dakota or places east.....
any authorized Heartland repair facilities near here?
We have a 2009 3410re Bighorn
Mark

 

[leftyf]

Wife just got shocked while reaching into the Micro/convection oven and bumping the oven hood with her arms. I tried the same thing and nothing happened. I then used a voltmeter, touching inside the door with red and grounding on the oven hood,, read 114
I then unplugged the Micro and get zero reading.
Will be calling the factory tomorrow..
we are In Yellowstone now and traveling east..... will need to find repair in Montana, North Dakota or places east.....
any authorized Heartland repair facilities near here?
We have a 2009 3410re Bighorn
Mark

Take your voltmeter,,,go outside and take a reading between the frame and earth ground. Let me know what the reading is.... I got a bet with myself...

OBTW...What are you using under your landing gear??

 

[karykatz]

Mark,

I am checking with our engineering dept. Will keep you posted what we find out. Hope you enjoyed Yellowstone.

 

[wdk450]

Mark:
You can take 2 more readings near the microwave to possibly isolate the problem.
With the microwave unplugged measure the resistance from the microwave plug to the bare metal chassis of the microwave. The reading should be just about 0 ohms. Then measure the resistance from the GROUND jack in the recepticle to the hood metal surface you measured to before. Again, you should measure just about 0 ohms. The first measurement checks the grounding of the microwave, the 2nd checks the grounding of the trailer wiring to the microwave outlet.
If there is a true live wire to metal fault within the microwave, with good grounding you would trip the circuit breaker, protecting you from shock.

Most modern digital appliances utilize powerline filtering that has a capacitive electrical leakage path to ground. The amount of current allowed in this leakage path is not life threatening, and will be completely negated by proper grounding. The bottom of the arm may be more sensitive/receptive to electrical shock than the hands, thus the shock was not felt by the hands. Also, the controls/latch are non-conductive plastic.

I know about this because in my 30 year career in medical electronics. Most digital consumer items will not meet the more stringent hospital electrical leakage testing done on every piece of electrical powered equipment with the grounding disconnected (worst case scenario), due to the consumer grade power line filtering. We discovered this in the early 1980's when the first IBM PC's started being bought for the hospital, and they ALL failed incoming inspections. Mitigating corrective actions had to be taken (isolation transformers, hospital grade replacement power input filtering modules).

Good luck!!

 

[whodoc]

I've got wood block under the front landing gear and the plastic stackable under the rear.
Voltmeter: frame to probe in ground(dirt) reads 1.0 to .8 on different areas of the frame.
I'm no electrician,,,,hope I have voltmeter hooked up right
Mark

 

[leftyf]

I've got wood block under the front landing gear and the plastic stackable under the rear.
Voltmeter: frame to probe in ground(dirt) reads 1.0 to .8 on different areas of the frame.
I'm no electrician,,,,hope I have voltmeter hooked up right
Mark

Remove the wooden blocks and get the rear onto the pad. If there is a problem with the grounding of the pedestal, you may have a grounding problem throughout your RV.

I always recommend that at least one of your jacks contact the dirt. The electric, usually done by a park employee, often has pedestal grounding messed up....and now your RV frame is acting like a return.

 

[whodoc]

I will try this in the morning! Thanks.
Mark

 

[Willym]

I'd be really concerned if we are depending on the trailer jacks/landing gear legs to provide grounding to the trailer electrical system. Proper grounding can only be achieved through proper supply wiring - i.e. at the pedestal. Appliances, secured to the trailer walls, and cabinets will not be grounded either unless they are plugged in to a properly grounded receptacle.

If the wiring at the park pedestal is faulty (this is not unusual) and no ground connection exists, then indeed, metal cases of appliances will become live when a live wire touches the case due to a fault, or where there is some induced voltage in the appliance case that cannot be dissipated to ground. The latter may be the problem in this case.

 

[jmgratz]

A good quality surge protector should indicate an open ground on the pedestal.

 

[JohnDar]

What then is the purpose of the heavy copper lines connected directly to the frame in the basement?

 

[Gaffer]

Everything is grounded to a common point to creat an equalpotential plane. Take an ohm meter or continuity checker to see that the grounding prong on the end of the appliance cord has continuity (0 ohms) to the frame of the applliance. If so check the receptacle for an open ground.

 

[leftyf]

What then is the purpose of the heavy copper lines connected directly to the frame in the basement?

tying all the individual grounds together at the frame. A return is ground to the pedestal...the real ground is the frame for both the AC/DC systems Keeps everything at the same potential..

I re-found out about frame grounds when I was in a campground with IFFY grounds. Add an Airstream to the mix...you got a real problem.

Lit *MY* world right up!!

 

[Willym]

What then is the purpose of the heavy copper lines connected directly to the frame in the basement?

Good question. What are these lines connected to at the other end?

 

[karykatz]

There have been several postings on the microwave. Heartland grounds the 12 volt converter, 110 service and gas live to the chassis. These are the copper cables you see connected to the frame. After further discussions with engineering and production regarding the shock form the microwave, since it was an isolated occurrence we believe it was a faulty ground at the campgrounds. However, if it continues to happen please get with your servicing dealer and have them check it out. It could be a faulty microwave.

Hope this helps. Thanks for all the input.

 

[Elevatorman]

Just some food for thought, while troubleshooting my converter behind the basement wall I did discover a ground loop that had come loose from the bug on the chassis. This would have disconnected the grounds for whatever area of the trailer it fed. I hadn't noticed anything wrong, but I'm sure something would have shown up eventually.