Wash, Shock, and Repeat: When Noodling Around Goes Wrong

In a 1970s house with a Federal Pacific panel, I encountered a peculiar situation. As I walked from the garage through the laundry to the house, the homeowner mentioned getting shocks from their appliances. Intrigued, I noticed a metal shelf, insulated with pool noodles, between the washer and dryer. The homeowner had attempted a fix by running a ground wire from the washing machine to the dryer plug. This was concerning, as the house, built in 1974, likely didn't have a ground wire in that plug.
The homeowner, a cheerful man, wasn't sure where he attached the ground wire. In a three-prong dryer plug without a ground, this could be risky. If he connected it to the neutral, it might be somewhat safer, but if not, he could have energized the dryer's housing. Worse, if the neutral wasn't bonded, connecting to a hot wire would energize the entire dryer shell.
Upon further inspection, I noticed the 120-volt plug behind the washing machine had been replaced and grounded, meaning the washing machine was safely grounded. However, the dryer next to it was potentially energized, creating a shock hazard.
This led me to a whiteboard session to explain the situation. The 1974 home had a 30 amp, 240-volt original plug without a ground - common for that era. The homeowner had connected a ground wire from the washing machine to the dryer, potentially energizing the dryer. If someone touched both the grounded washer and the energized dryer, they could complete the circuit, causing electricity to flow through their body.
I pondered whether a GFI (Ground Fault Interrupter) would have prevented this. If the plug had been GFI-protected, it might not have tripped since the washing machine's current loop would be continuous, with no apparent loss. The addition of current from the dryer circuit might not trigger the GFI either.
This situation highlighted the dangers of DIY electrical work, especially with older appliances and wiring. The use of pool noodles as a makeshift safety measure was both ingenious and alarming. It underscored the need for professional intervention in such cases to ensure safety and compliance with electrical standards.
In summary, this experience in the 1970s house revealed a risky DIY electrical setup, where a lack of grounding and improper connections created a significant shock hazard. It emphasized the importance of proper electrical safety and the potential dangers of amateur electrical fixes.
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[@mike_realityi]

A home owner that knows enough to be dangerous BUT also knows when I don't know what I don't know and when to stop. With this house being a '74 built then it may not have had a properly grounded receptacle, Handy Homeowner replacement. You can not assume washing machine outlet has been properly upgraded without opening it up or at least throwing a tester in there. I wanna bet that there is a short in the washer to the frame, open ground in the washer receptacle and when the current homeowner would touch the washer & dryer they "closed" the circuit to the bonded dryer Neutral/Ground in the dryer which would cause the shock.

[@felaxchow207]

Yep, knowing enough to be dangerous and electricity certainly makes strange bedfellows. A properly wired washer circuit with a GFCI outlet and stray current going from the dryer case to the washer case would not trip it. The current sensor in the GFCI is monitoring the current imbalance of the washer appliance itself for any current leakage and any external current would just travel from your hand on the dryer case to the washer case to the ground pin of the receptacle back to the service panel. From the picture of the clothes dryer, it looks like the new electronic control style. I've ran into a situation where the neutral is bonded to the case using the old 3 prong dryer cord and the neutral was faulty between the cord to the receptacle or receptacle to the service panel. The electromechanical timer motor would just quit working and the dryer just runs non-stop, but if you touch the case to something that is grounded while it's running; you get a bit of a zinger. Dryers with electronic boards however doesn't require a whole lot of current for them to power up and if the damp concrete floor is conductive enough to pass from the neutral bond of the dryer case to complete the circuit. What I experience from it is the controller would start to freak out when it is started or stopped. I've even seen neutral to case bond circuit completed just by stainless steel braided hoses touching the dryer case going through the plumbing system. As of late, my municipality now requires GFCI protected receptacles in garages and laundry areas including dryer circuits. I get quite a handful of random nuisance GFCI tripping calls caused by neutral to case bonding jumpers not being removed when a four wire dryer cord installed by homeowners.

[@teseract]

As the dryer was hot, and the pool noodles were insulation, wouldn't the pool noodles need to be black or red to signify they're insulating a hot conductor? Though a dryer chassis is technically a 4 gauge or larger conductor so code would allow you to use any color pool noodle you liked, as long as it was wrapped with red or black tape or some another marking method to indicate they were the insulation of hot conductors. Too bad we don't use 3 phase in residential settings in the USA, otherwise you'd be able to have a whole slew of color selections on offer. 0:)

[@abrelectric]

Hahaha! Makes sense 😀

[@Ryan-en7sl]

Okay I will take a shot at this. 3rd year apprentice here. If the chassis of the washing machine is grounded to the GFI, then any current that reaches the chassis of the washer (via someone touching both applicances), then the extra current would flow through the GFI, tripping it, as long as there is more than 5mA going to ground.... How does this answer sound? Im looking at this to be educated as well so Iam looking forward to any responses.

[@mike_realityi]

Hello, Just a home owner here. The Washer circuit is not currently GFI protected. The comment about GFI was a thought experiment. I agree with the current to the washing machine chassis. I am thinking that when upgrade from unground to ground receptacle the upgrade was not done properly. More than likely it was a handyman homeowner upgrade from the hardware store to be able to plug in their new grounded washing machine. Old school MC wire only carried a hot and a neutral, 12/2 and no ground. The conversions from ungrounded to grounded would rely on the MC shell being properly bonded to the outlet box and back at the panel, and any junctions along the way. I live in a home built in 1935. I still have 1 or 2 ungrounded outlets. The old boxes were very small and can make things like GFI extremely hard to fit in.