Shopsmith Forums

JPG40504 wrote:UL 'approval' and GFCI compatibility are different things. One doesn't 'guarantee' the other!

For a protective device that exists merely as a backup for other safety schemes, the GFCI is not only 'overkill', but a not so consistantly designed device (IMHO). Sorta like an acorn falling out of the sky!:D

I disagree that a GFCI should work with all 'safe' UL approved appliances.

I totally disagree. Any UL device would by definition work with GFCI.

I also totally disagree that GFCI is overkill. If the ground wire breaks and if power gets into contact with the case without GFCI you become the ground and you can get the full potential of current through you. Tell the thousands of people that didn't get shocked that GFCI is overkill.

As far as being consistently designed, I couldn' speak to that but I believe a lot of GFCI problems have been contributed to bad design when in fact they were working properly. I have seen more than one electrical outlet wired improperly by a "Master" electrican. It happens especially with multi drop and two and three way circuits.

I think the devil is in the details.

Some web-searching suggests that the Leakage Testers specified in UL compliance-testing are not necessarily capable of assessing high-frequency ground currents. See for example:
http://www.ul.com/asiaonthemark/as-en/2 ... /page8.htm

So, it can well be that the PowerPro is UL-compliant yet still has some high-frequency ground currents. My multimeter suggested 3.5mA ground-currents on my PowerPro, if I recall correctly now. And there was *no* DC leakage-resistance measurement anywhere near that expected magnitude (120v/3.5mA for instance).

When I toured Shopsmith/Dayton in 2008, they were performing high-potential leakage tests on every tool they made. Even including the bandsaw which has no motor.

If the UL catches up with the modern age, maybe it will mandate a change to the PowerPro circuitry.

nuhobby wrote:I think the devil is in the details.

Some web-searching suggests that the Leakage Testers specified in UL compliance-testing are not necessarily capable of assessing high-frequency ground currents. See for example:
http://www.ul.com/asiaonthemark/as-en/2 ... /page8.htm

So, it can well be that the PowerPro is UL-compliant yet still has some high-frequency ground currents. My multimeter suggested 3.5mA ground-currents on my PowerPro, if I recall correctly now. And there was *no* DC leakage-resistance measurement anywhere near that expected magnitude (120v/3.5mA for instance).

When I toured Shopsmith/Dayton in 2008, they were performing high-potential leakage tests on every tool they made. Even including the bandsaw which has no motor.

If the UL catches up with the modern age, maybe it will mandate a change to the PowerPro circuitry.

I think the real question is does the PowerPro carry the UL certification? If it does then I would say any Power Pro that trips a properly functioning GFCI is defective. And if the Power Pro does not carry UL certification what is the insurance industries position of incidents where non UL approved devices were used? I believe OSHA's take is it either must be UL or OSHA approved or it isn't allowed in commercial applications.

Ed in Tampa wrote:I think the real question is does the PowerPro carry the UL certification? If it does then I would say any Power Pro that trips a properly functioning GFCI is defective. And if the Power Pro does not carry UL certification what is the insurance industries position of incidents where non UL approved devices were used? I believe OSHA's take is it either must be UL or OSHA approved or it isn't allowed in commercial applications.

I don't believe that Shopsmith machines are UL-listed. They may be using UL-listed components, and they may be building to practices such that the machines would pass UL-testing, but I don't believe that the Shopsmith themselves are UL-listed.

JPG40504 wrote:There is quite a difference between the conductivity of damp objects including concrete and metallic objects like plumbing(metal pipes). There be a difference between getting 'tingled' and getting electrocuted. Neither are to be 'encouraged', but the risk factor is quite different......... also includes the rest of your post..

Thanks for your entire post.... putting a little more reason into the discussion.

Will take your words under advisement.

Ed in Tampa wrote:I think the real question is does the PowerPro carry the UL certification? If it does then I would say any Power Pro that trips a properly functioning GFCI is defective. And if the Power Pro does not carry UL certification what is the insurance industries position of incidents where non UL approved devices were used? I believe OSHA's take is it either must be UL or OSHA approved or it isn't allowed in commercial applications.

Ho-kay! Another worm has crawled into this basket! The old Mark 5's have not only UL approval, but also have the CSA logo engraved on the nameplate(the one above the quill lock). I do not recall any instruction to remove it when installing the pp innards!

I be real curious what the hi-pot test on the band saw(sans electrical wiring/devices) was connected between?

I am not an advocate of a return to the 'good old days' of little or no 'protection' but I am skeptical of the adequacy of the 'current' (pun intended) GFCI scheme to provide total protection so we can willy nilly go around oblivious to electrical hazards.

As you pointed out broken wires and incorrectly installed devices subvert the previous 3 wire grounding scheme. This is a reason a 'permanently' wired (no plug/receptacle) is safer('acceptable') in a garage, however, even that is still dependent on yer friendly master electrician and appliance creator!

However recent appliances(those portable things plugged into power receptacles) have a need to suppress RF Interference due to the high frequencies contained within. The rfi suppression attached to the power input wiring is to prevent that 'noise' from feeding back into the power grid (which will then act as an antenna). Unfortunately they also provide a leakage path which increases(leakage) with frequency so that a noise/transient spike may trigger the GFCI. These 'detected' spikes post no hazard to an operator but hence become a nuisance trip.

BTW a producer of electrical equipment that contains these RFI suppression capacitors must use capacitors($) capable of with standing the hi-pot voltage and allowing for the resultant 'leakage' by increasing the tester limit, or disconnect them during the 'leakage' test. (assuming 100% product testing - not always an accurate assumption)

As a side note: I have my amatuer radio station located in my basement with my woodworking shop. The PowerPro emits a tremendous amount of rf. I have to turn off all radios (especially the old tube types) whenever I switch the power pro on.

Ken - N8KJG