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  • Power Tool Earth

    I was looking at power drills in Home Depot the other day and was quite taken by the Ridgid models. However, one thing disturbed me. None of the power tools have a grounded power cable. This includes all the competitors models.

    All of the Ridgid drills I looked at have an exposed metal gearbox which is electrically connected to the drill bit. What protection mechanisms are in place to stop me getting a shock from the gearbox if I accidentally drill an electrical cable (e.g. buried in a wall etc) or if the tool developed an internal short circuit? This is actually a more general question as I see metal chassis hi-fi equipment and other stuff with a 2-pin plug (no earth).

    In the UK (where I am originally from) such a product would not be allowed on the market where tools with exposed metal surfaces must be earthed. What rules in Canada and the US determine what does and doesn't have an earth connection?
    Last edited by skelband; 08-12-2008, 12:40 PM.

  • #2
    Re: Power Tool Earth

    I assume that the drills you saw were double insulated:
    http://en.wikipedia.org/wiki/Double_insulated#Class_II

    My DeWalt corded drill is. I don't know how it actually works, but they are supposed to build it in a way that is safe.

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    • #3
      Re: Power Tool Earth

      In the UK, I had a Bosch drill (I wish I still had it - it was great). But yes, it was actually double insulated and therefore, apart from the chuck (of course), was all plastic externally.

      The Ridgid drills I saw have a metal gearbox which is inevitably connected to the bit by a clear electrical path. Its not all that uncommon to drill something dangerous by accident (not that I've actually done that myself I might add ) but it seems daft that, for the slight extra cost of an earthed cord, that danger could be eliminated.

      Admittedly, you can rely on a GFCI for protection against an internal short, a blast from a separate circuit that you've just accidentally drilled through is not necessarily protected in that way.

      Electrical stuff is quite different here and I am still learning - in the UK, a plug must have an earth pin, but it may be plastic or unconnected if the appliance does not require an earth (double insulated for example) but here there are two pin plugs which complicate it somewhat.
      Last edited by skelband; 08-12-2008, 12:30 PM.

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      • #4
        Re: Power Tool Earth

        Suggestion

        Take a good look at a Milwaukee model 0234-1 which will have 0234-6 on the box. It comes with a 3 conductor removable grounding (earthing) power cord as standard equipment. It's a high quality 1/2" (12.5mm) capacity variable speed reversible pistol grip style drill. Here in the USA it has been a good workhorse drill for many years. While there are power tools that are double insulated regarding the motor it does bother me when they have metal gear cases which are not grounded. Please, by all means use a GFCI receptacle or a plug-in portable CFCI device with all corded power tools. It just may save you from getting zapped.

        More information on it
        http://www.milwaukeetool.com/webapp/..._192159_192137

        I need to add that several other models such as the 0300-20 are claimed to be double insulated and don't have grounding.

        I do not like this. I want all exposed metal parts of any power tool to be grounded. Then on the other hand think about cordless tools.

        You might wish to contact electrical supply houses, industrial suppliers and safety equipment dealers. Ask about dielectric gloves for electricians. This is going a bit on the wild side of safety but they are far better for protection from electrical shock than wearing regular work gloves.

        When drilling or sawing always try really hard to shut off power to any electrical circuits in the work zone. Also, try to locate electrical wiring and conduit before you start work. Prevention is your best bet.

        Here in the USA I have seen too many people remove the grounding pin on power cords. Also, there are too many poor receptacles and worse yet poor installations where a grounding device isn't properly grounded at all.

        Regarding RIDGID brand corded drills at one time they contracted with Metabo over in Germany to make them. Anymore they are TTI products and most are made in China anymore. That doesn't mean they are junk, but I doubt very much they have the same quality.

        Welcome to the USA the land of crazy people and a different language than pure English. We do use different names for things than over in the UK.
        Last edited by Woussko; 08-12-2008, 01:24 PM.

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        • #5
          Re: Power Tool Earth

          Thanks for the suggestion Woussko.

          I have a 21V cordless and its good and all but it doesn't really have the umph that a corded drill has for masonry work.

          He-he I know what you mean about dodgy connection to the mains. In the UK, the live conductors are protected by shutters that are opened by the earth pin but I've seen matchsticks used to get around this where bare wires are inserted into the socket

          It's such a shame - from what was on display, the Ridgid tools rocked and the price was right. I'm not sure what to do now - either keep looking or suck it up and get the Ridgid drill anyway....and just not hold it by the gearbox

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          • #6
            Re: Power Tool Earth

            Correct on not holding the gear box. The plastic side handle offers some protection. Do everything you can to prevent drilling into live wires.

            Put simple: KNOW where the hazards are and do all you can to stay clear of them. If in doubt shut off power to any circuits in the work area.
            Last edited by Woussko; 08-12-2008, 04:08 PM.

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            • #7
              Re: Power Tool Earth

              Originally posted by skelband View Post
              The Ridgid drills I saw have a metal gearbox which is inevitably connected to the bit by a clear electrical path. Its not all that uncommon to drill something dangerous by accident (not that I've actually done that myself I might add ) but it seems daft that, for the slight extra cost of an earthed cord, that danger could be eliminated.
              I suspect that the reason is the drill might need to be used in a house w/o grounded receptacles (my parent's house built in ~1960 is like that).

              I've actually managed to drill into a live wire while trying add a lag bolt to secure my son's dresser to the wall so he couldn't tip it over on himself. I just glanced off the side of a stud right into the wire. Fortunately my Ryobi cordless is made of plastic.

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              • #8
                Re: Power Tool Earth

                Originally posted by cpw View Post
                I suspect that the reason is the drill might need to be used in a house w/o grounded receptacles (my parent's house built in ~1960 is like that)
                You could be right about that.
                I will look at them again and have a think!

                Thanks for all the comments guys - it's given me a lot to think about!

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                • #9
                  Re: Power Tool Earth

                  This doesn't always work as most new plugs have one prong larger than the other to observe polarity. The outlets in my parent's 1950's house won't work with a polarized plug unless you have an older adapter.

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                  • #10
                    Re: Power Tool Earth

                    Originally posted by skelband View Post

                    What protection mechanisms are in place to stop me getting a shock from the gearbox if I accidentally drill an electrical cable (e.g. buried in a wall etc) or if the tool developed an internal short circuit? This is actually a more general question as I see metal chassis hi-fi equipment and other stuff with a 2-pin plug (no earth).
                    If the tool has no grounding pin it should be classified as double insulated. Any external conductive part on the tool has to be completely isolated and insulated so the tool is safe even from an internal short. You do bring a good point that it doesn't protect from external electrical sources.

                    I have plenty of corded tools with metal gear casings and no ground prong. I suppose some of them are tools that are very unlikely to be in such a situation, or even extremely unlikely to be handled from the metal during operation.

                    I think just about the only tool I have that came with a 3 prong plug is the rotary hammer which has a metal gearcase. That is certainly something I'd never use without as it could easily blow right through embeded conduit you might not know is there. On the other hand my hammer drill also has a metal casing has no ground prong and runs similar risk. The funny thing is I take the handle off the drill sometimes and hold it from the gear case which tends to be more comfortable. It's unlikely anyone would do that on the roto hammer, besides being difficult to control the heat makes it impossible to handle from the casing even with gloves.

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                    • #11
                      Re: Power Tool Earth

                      Originally posted by cpw View Post

                      I've actually managed to drill into a live wire while trying add a lag bolt to secure my son's dresser to the wall so he couldn't tip it over on himself. I just glanced off the side of a stud right into the wire. Fortunately my Ryobi cordless is made of plastic.
                      Happened to my dad too when I was really young. Drilling into a wall he hit a romex wire that had been embeded just under the surface mortar of a concrete wall for some inexplicable reason and abandoned there going nowhere. There's no way anyone could have known given all the wiring should have been in embedded emt conduit much deeper in the wall. I remember the large burnt black spot in the wall it left. I have no idea how he didn't get zapped. There were no grounding outlets installed back then and he was using an old all metal drill which I doubt would even have been grounded. I think he got lucky and split it right between the hot and neutral so it shorted right accross the drill bit.

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                      • #12
                        Re: Power Tool Earth

                        I have the 14.4 ridgid impact and in the owners manual it states that you should not hold onto the drill by the metal casing if you think there is a chance of drilling into a live wire.

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