2 prong metal drills

[mbrooke]

If the NEC required that drills have an EGC since at least the 50s, and that outdoor receptacles be grounded, then why were there so many 2 prong plugs? Were people just cutting off the ground pins?

 

[GoldDigger]

The advent of a standard for double insulation changed all of that.
The rule now is either grounded (EGC with 3 wire cord) OR double insulated (2 wire cord OK).

 

[drcampbell]

Why? Because there wasn't tight coordination between all the various people involved.

People were removing ground prongs long past the 1950s. It was fairly routine at a facility I maintained in the 1990s.
At least for a while ... until I bought a box of a hundred grounded replacement plugs, then began cutting off "damaged" plugs whenever I spotted one.

 

[tom baker]

I was a mechanic in the Navy - early 1970s when double insulated tools came out. The nuke electricians were perplexed with the new double insulated drills, they had no way to megger test. It was amusing to us.
I do recall when I joined the IAEI in 1980s they had reprinted articles on electrocutions- a lot under a house with a metal cased drill.

 

[mbrooke]

The advent of a standard for double insulation changed all of that.
The rule now is either grounded (EGC with 3 wire cord) OR double insulated (2 wire cord OK).

Right, but before that you still had metal drills somehow ending up without an EGC.

 

[mbrooke]

I was a mechanic in the Navy - early 1970s when double insulated tools came out. The nuke electricians were perplexed with the new double insulated drills, they had no way to megger test. It was amusing to us.
I do recall when I joined the IAEI in 1980s they had reprinted articles on electrocutions- a lot under a house with a metal cased drill.

Yah thats what I keep coming across. Metal case drills becoming live. But I can't see how so many drills would become live if the NEC required that they be grounded?

 

[mbrooke]

Why? Because there wasn't tight coordination between all the various people involved.

People were removing ground prongs long past the 1950s. It was fairly routine at a facility I maintained in the 1990s.
At least for a while ... until I bought a box of a hundred grounded replacement plugs, then began cutting off "damaged" plugs whenever I spotted one.

Why were they cutting off ground prongs?

 

[drcampbell]

Sometimes it was an ill-advised attempt to reduce instrumentation noise.
Usually, they didn't have a good reason. Either it works without it, or they learned it from their dad, I suppose. In any case, the practice didn't persist long after I made it a habit to never leave my office without a pair of dykes in my pocket.

A solidly-grounded handheld power tool can be a hazard if you encounter something hot. Double-insulated will protect against that, as will a GFCI.

 

[mbrooke]

Sometimes it was an ill-advised attempt to reduce instrumentation noise.
Usually, they didn't have a good reason. Either it works without it, or they learned it from their dad, I suppose. In any case, the practice didn't persist long after I made it a habit to never leave my office without a pair of dykes in my pocket.

A solidly-grounded handheld power tool can be a hazard if you encounter something hot. Double-insulated will protect against that, as will a GFCI.

Can I ask. Were your garage, outdoor and laundry room outlets grounded in the 50s?

 

[drcampbell]

Can't say.
I was born in 1959. My folks bought a house in 1962 and had a new panel installed, and I suspect that if there were any 2-wire receptacles, they were changed to 3-wire at the time. I don't recall ever dealing with 2-wire receptacles or grounding adapters there, and they stayed until 2005, by which time I was well aware of things. It's in Chicagoland and wired with steel EMT, so adding ground wires would have been easy.

 

[steve66]

Yah thats what I keep coming across. Metal case drills becoming live. But I can't see how so many drills would become live if the NEC required that they be grounded?

Many hand tools were double insulated with a metal case (before plastics became so popular) and no ground connection.

I remember my dad had a circular saw like that. I always thought just holding onto the metal case and turning it on was scary.

Probably wouldn't be good to be cutting into a wall or floor and accidentally cut through a piece of hot NM cable or something similar.

 

[mbrooke]

Many hand tools were double insulated with a metal case (before plastics became so popular) and no ground connection.

I remember my dad had a circular saw like that. I always thought just holding onto the metal case and turning it on was scary.

Probably wouldn't be good to be cutting into a wall or floor and accidentally cut through a piece of hot NM cable or something similar.

So how were all those drills livening up?

 

[paulengr]

Plenty of tools are STILL doubly insulated without ground pins from the factory like concrete drills and grinders. Metal is not used as much simply because plastic is actually superior in many instances. Just as tough if it’s thick enough with higher flexibility so it takes impact better.

 

[mbrooke]

Plenty of tools are STILL doubly insulated without ground pins from the factory like concrete drills and grinders. Metal is not used as much simply because plastic is actually superior in many instances. Just as tough if it’s thick enough with higher flexibility so it takes impact better.

I know. But I can still buy toasters, grills, space heaters, ect without a ground and not double insulated.

 

[GoldDigger]

Yeah. There appears to be an exception for some heating appliances. But except for the exposed resistance element in open air they still can be double insulated.

 

[mbrooke]

Yeah. There appears to be an exception for some heating appliances. But except for the exposed resistance element in open air they still can be double insulated.

Right, though often aren't double insulated.

 

[jmellc]

Why? Because there wasn't tight coordination between all the various people involved.

People were removing ground prongs long past the 1950s. It was fairly routine at a facility I maintained in the 1990s.
At least for a while ... until I bought a box of a hundred grounded replacement plugs, then began cutting off "damaged" plugs whenever I spotted one.

I have seen countless male plugs where the ground pin broke before the rest of the plug even showed any wear.

 

[mbrooke]

I have seen countless male plugs where the ground pin broke before the rest of the plug even showed any wear.

I'm thinking a flat EGC would've been better, as history once had it.

 

[drcampbell]

Lots of different designs could have been better.
The German Shuko ("Schutzen Kontakt" ... protective) has a recessed earth conductor -- there isn't anything that can be removed, nor any reason to. It's also completely finger safe - the plug is completely recessed inside the receptacle before the pins make contact.

 

[paulengr]

Lots of different designs could have been better.
The German Shuko ("Schutzen Kontakt" ... protective) has a recessed earth conductor -- there isn't anything that can be removed, nor any reason to. It's also completely finger safe - the plug is completely recessed inside the receptacle before the pins make contact.

View attachment 2555936

Somebody has to be first. And somebody else designs a better mousetrap.

Originally all plugs didn’t even have a ground pin. That was added later. That was also at a time when it was believed that electricity was dangerous but the insane consumer product safety regulations didn’t exist so manufacturers weren’t responsible for the utter stupidity of the customers. The reasonable person rule applied. Today you’d need something like an Arktite plug. These are for 480 plugs. There is a disconnect with a mechanical linkage. The linkage drives a pin through a hole in the plug. You cannot insert or remove the plug unless the disconnect is in the off position so power is always off when you are plugging or unplugging it. Drives welders crazy!