Why don't (some) power tools have ground wire?

[Mohawk Dave]

My buddy cut through my grinder cord last night, and we got to talking....most grinders, skils, drills, etc do not have a ground cord? Why not?

Can/should you replace it with a grounded cord? (I like using Ridgid Extension cords to replace when needed) Could/should you wire the ground inside the housing?

I'm in the dark on electrical. Thanks!

 

[Kracin]

double insulated bodies that protect against grounding shock may not require it

look for a square within a square symbol. means it is double insulated.

a lot of tools like that may still have a ground wire though as a failsafe and backup safety.

 

[plinker]

If the tool has a metal case usually they have a ground wire in the cord. All plastic or mostly plastic tools are "double insulated" therefore you do not need one due to the fact that you are not holding a solid metal power tool that can shock you. That's the theroy anyway (as I know it).

 

[Outlawmws]

If that way from the factory, (and not really old, predating the OSHA standards) it's is because they are 'double insulated" Notice those tools have plastic handles, not metal?

Old hand held power tools I always upgrade to grounded...

 

[Mohawk Dave]

ok. great. so you on my all metal grinder that I just posted as well- http://www.garagejournal.com/forum/showthread.php?t=195117- I should replace the cord with a grounded one.

Outlaw-do you just find a place in the body to secure the ground? (Maybe answer in the other thread for others to see..IDK??)

 

[ryanhelton2000]

Yup to the body on the inside just like you would a light fixture.

 

[rlitman]

Yes, any electric tool with an all metal body should be grounded.
Metal gearbox only, not necessarily.

If it wasn't grounded in the first place, I'll usually crimp a ring terminal on the ground wire, and attach it to some screw inside that threads into the metal (like the screw holding the switch in place).

 

[Roots]

If the tool has a metal case and a ground wire, you should also periodically check for continuity to ensure it's still functional. I've taken many out of service for failing.

 

[Outlawmws]

ok. great. so you on my all metal grinder that I just posted as well- http://www.garagejournal.com/forum/showthread.php?t=195117- I should replace the cord with a grounded one.

Outlaw-do you just find a place in the body to secure the ground? (Maybe answer in the other thread for others to see..IDK??)

Yup to the body on the inside just like you would a light fixture.

 

[Mohawk Dave]

If the tool has a metal case and a ground wire, you should also periodically check for continuity to ensure it's still functional. I've taken many out of service for failing.

Roots, would you be kind enough to explain how to do that. I'm a novice on sparky stuff. Thank you.

 

[5mall5nail5]

Roots, would you be kind enough to explain how to do that. I'm a novice on sparky stuff. Thank you.

Multimeter in continuity oh resistance mode.

close to 0 ohms resistance when touching the body (make sure you're not touching a painted surface) to the ground pin on the electrical cord. As close to 0 ohms as possible. < 1 ohm.

 

[ryanhelton2000]

Multimeter in continuity oh resistance mode.

close to 0 ohms resistance when touching the body (make sure you're not touching a painted surface) to the ground pin on the electrical cord. As close to 0 ohms as possible. < 1 ohm.

Yeah I like it here, people actually know what they're talking about I see myself spending way to much time on here.

 

[cryan]

Most power tools here in the UK are grounded although all plugs must have a ground pin even if not conected (wall receptacle wont allow live and neutral pins in without earth pin). Also all domestic type plugs are fused. Commercial owned eletrical items must be tested annualy for insulation resistance known as PAT testing (Portable Appliance Test).

 

[bonneyman]

If the tool has a metal case usually they have a ground wire in the cord. All plastic or mostly plastic tools are "double insulated" therefore you do not need one due to the fact that you are not holding a solid metal power tool that can shock you. That's the theory anyway (as I know it).

That's what I'm thinking. Not that I'm a big fan of plastic tool bodies, but, many of the new polymers are much better insulators than the old kinds.

 

[Tdex]

Bumped into this old thread I felt I should reply . Many yrs ago I witnessed a friend get electrocuted because of a tool with that third prong ground.
Don’t replace a two prong with a three prong wire and plug.

When using a cutting, drilling or shaping tool there is always a chance of inadvertently cutting into a live wire, that live wire will be looking for a ground, and it will have found an excellent one in that that ground wire plug, and the tool holder is now the bridge, result, serious electric shock.
So there is good reason why manufacturers now double insulate cutting tools.

 

[Outlawmws]

Tdex, you are missing the POINT of the ground wire. That wire provides the lowest path of resistance to either drilling into a live wire, OR a short circuit in the tool itself.

Without it, YOU the user becomes the lowest path of resistance to ground from your hand to wherever your body happens to be grounded. If your opposite hand or feet is that path, it is straight through your heart. Deader!

If your friend was electrocuted, that ground was either not functional, Or it was plugged into a receptacle that had never been properly grounded, (I see this commonly in older homes before grounded plugs became the norm, where some nimrod replaced with a three prong receptacle and didn't connect it to a ground, because it wasn't there to connect...)

Double insulated tools ARE safer; however that double insulation is what allows them to go with a two prong plug safely the two prong without the double insulation is NOT safe..

 

[sberry]

Gfci is the great failsafe.

 

[Al Borland]

^^^Doesn't do a damn thing on a double-insulated tool with a 2-prong plug^^^

 

[andrew61987]

^^^Doesn't do a damn thing on a double-insulated tool with a 2-prong plug^^^

GFCI doesn't? I don't agree.

 

[Captain Spaulding]

^^^Doesn't do a damn thing on a double-insulated tool with a 2-prong plug^^^

Yes it does. The current doesn’t have to flow through an EGC for a GFCI to work. The GFCI doesn’t detect current flowing in the EGC, it detects a difference in what flows in the hot and neutral. Doesn’t care where it’s going, it just knows it’s going somewhere it’s not supposed to.

 

[The Cobbler]

^^^Doesn't do a damn thing on a double-insulated tool with a 2-prong plug^^^

another one that disagrees

drop an ungrounded something, plugged in to a GFI, into a pail of water and see what happens

 

[ddawg16]

I have an old Craftsman sander.....metal case....2 prong.....Makes a nice ornament for the shelf.....though, it does work.

Regarding GFCI's and EGC.....the GFCI trumps a EGC any day.

In older houses with no EGC, a GFCI is a good way to make outlets 'safer'.

You can still have a tool with a ground....but it does not necessarily make it safer. At the end of the day, a properly wired and working GFCI is the best protection.

 

[sberry]

Don't take it personal, this is a tuff crowd.

I know an installer, steel that thinks grounding and gfci is a pain in the ***. A poster child for why they invented it. Don't know how they havnt been jammed up for it. Wouldn't hurt his lights to be on it.
I bought him 3 or 4 cords, he had account for a job at the store and I just buy some on his account. Power strip has a faulty plug, every piece down stream provided its plugged in to a grounded cord is faulty unless it was made 2 wire. Gfci is a savior, wet steel.
Ground and insulated neutral was a leap.

 

[Wamsutta]

The ground wire on the cord is only as good as the ground wire on the receptacle (if it has one) or so I've been told.

 

[sberry]

The code kind of assumes every step of the installation, the grounds, bonds, continuity etc is and has been done correctly. GFCI makes up for it. A breaker is really better but that's a pain, eliminates the potential for ground fault to the first device but somehow that would need to be thought thru.