Shopsmith Forums

Two more cents worth! Back when GFCI were just becoming available, we encountered problems with them because of the power line distributed clock correction system. The system injected a short higher frequency signal on the power 'grid' just prior to each 'top o the hour'.

The existence of rfi suppression capacitors in some equipment provided a convenient path for current through the rfi capacitor at this higher frequency. The resultant current was greater at the higher frequency. In addition to that, some GFCI models were more sensitive at the higher frequency(yes I measured frequency response = some tripped at less than 1 ma at the higher frequency). The guy down the road at Square D was quite delighted to be informed of that!

Now the point here is different models have different trigger characteristics, so that can explain some of the conflicting experiences.

I am assuming(guessing) the power supply for the pp has a small capacitor connected between each power conductor(black, white) and the grounding conductor(green). When connected to 230V the capacitors currents flow through both in an equal but opposing polarity. When connected to 115V, the capacitor connected to the hot(black) conductor does not have an opposing current from the neutral(white) connected conductor, and that current flows through the grounding conductor(green). Bingo! Leakage current that the GFCI is designed to detect!

Now what about the risks involved if one uses a non-GFCI protected source for the pp. As long as the pp and the circuit are properly grounded, the primary safety protection function is 'alive and working'. The purpose of the grounding conductor is to protect an operator from any leakage(or fault) current by providing a lower resistance path for that current(lower than through the operators body). The GFCI are (partially) a secondary backup protection(in case the grounding conductor gets broke[or circumvented]).

Now the GFCI protection scheme has the added advantage of being independent of external influences(such as broken grounding wires or 2-3 wire adapters).

So IMHO connect to a non-GFCI outlet and be diligent in making sure
the grounding conductors are always functional.

Best scenario is however a grounded 230V branch circuit.

I can't believe Shopsmith can get UL approval if there is any issue with Ground Fault breakers. That makes me suspect they aren't UL approved. If that be the case check your insurance, you may find you aren't covered from any incident involving a non UL approved electrical device.

Personally I believe this problem needs to be resolved and removing GFCI breaker or protected wall plugs is not a resolution.

my bet is that either a wire is pinched and shorting to case ground or its the crap import receptacle. Went through 3 brand new GFI receptacles to find one that worked back in October. Didn't buy them at a box store and they were not made in the US of A.

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.

JPG40504 wrote: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).

But REQUIRED by CODE in certain parts of the house.

JPG40504 wrote: The purpose of the grounding conductor is to protect an operator from any leakage(or fault) current by providing a lower resistance path for that current(lower than through the operators body). The GFCI are (partially) a secondary backup protection(in case the grounding conductor gets broke[or circumvented]).

I was taught (by an electrician) that standard circuit breakers are actually designed to protect the electrical system from short circuits. A byproduct of that electrical system protection is a limited amount of protection to electrical equipment and incidental protection to electronics and people.

GFI/GFCI protection either in the breaker panel or at the outlet is designed to protect people where current is leaking to ground (hence the build code requirements in areas where electricity and water are likely to be in proximity)

To protect electronic equipment a surge suppressor is the correct device.

Just what I was taught.

,,........................

beeg wrote:But REQUIRED by CODE in certain parts of the house.

Yep! Anywhere there is a potential that one might simultaneously grasp a grounded surface(plumbing pipe/fixture etc.) and a 'defective' device or accidental submersion of a device into the water. Requiring them in a garage or workshop is a bit too much unless low resistance contact with a metallic(conductive) grounded surface is possible.

I have no axe to grind re their required locations(better 'safe than sorry'), but I do take issue with their rampant(IMHO) inconsistent operation and frequent 'nuisance' tripping. 'Nuisance' = unexplained. i.e. no apparent cause. They need to be less sensitive to power line transients.

I standby my assertion that a properly grounded device and source is safe without a GFCI. However the grounding must NOT be compromised!!!

terrydowning wrote:I was taught (by an electrician) that standard circuit breakers are actually designed to protect the electrical system from short circuits. A byproduct of that electrical system protection is a limited amount of protection to electrical equipment and incidental protection to electronics and people.

GFI/GFCI protection either in the breaker panel or at the outlet is designed to protect people where current is leaking to ground (hence the build code requirements in areas where electricity and water are likely to be in proximity)

To protect electronic equipment a surge suppressor is the correct device.

Just what I was taught.

You be taught well! Those facts are too often overlapped where inappropriate!

JPG40504 wrote:,,........................

Yep! Anywhere there is a potential that one might simultaneously grasp a grounded surface(plumbing pipe/fixture etc.) and a 'defective' device or accidental submersion of a device into the water. Requiring them in a garage or workshop is a bit too much unless low resistance contact with a metallic(conductive) grounded surface is possible....!!

YES, BUT!! Since my shop is built on a concrete slab and I use hand held electrical tools - some of them very elderly - it is a matter of additional safety. There is no vapor barrier beneath the concrete.

Admittedly, there is but little chance of a live wire coming in contact with the chassis of the Shopsmith. But little chance leaves the door open.

Also, although I'm usually standing on a rubber pad, the Shopsmith is on the concrete. Using other tools (and sometimes the Shopsmith) I will stand on concrete, which is grounded and sometimes damp, it is a wise thing to have GFIs.

Remember the cases (mentioned in this forum) of boards stored on concrete have developed additional checking and/or moisture as a result of this storage. (Additional end checking from standing on end leaning against a wall - and added moisture from flat storage.)

I remember well, the little portable radio I had - a Philco, with a metal case that would give me a tingle from time to time. Also remember the times in the Army when operators would report shocks from their electric machines. The fix in both cases was to reverse the plug in the socket. OH! for the good ol' days, and only two equally sized blades on a plug. I also remember those new tools purchased in the early 50s, with the three pronged plugs. We'd break off the ground prong so they would fit in our old receptacles. Times have changed!

[quote="charlese"]YES, BUT!! Since my shop is built on a concrete slab and I use hand held electrical tools - some of them very elderly - it is a matter of additional safety. There is no vapor barrier beneath the concrete.

Admittedly, there is but little chance of a live wire coming in contact with the chassis of the Shopsmith. But little chance leaves the door open.

Also, although I'm usually standing on a rubber pad, the Shopsmith is on the concrete. Using other tools (and sometimes the Shopsmith) I will stand on concrete, which is grounded and sometimes damp, it is a wise thing to have GFIs.

Remember the cases (mentioned in this forum) of boards stored on concrete have developed additional checking and/or moisture as a result of this storage. (Additional end checking from standing on end leaning against a wall - and added moisture from flat storage.)

I remember well, the little portable radio I had - a Philco, with a metal case that would give me a tingle from time to time. Also remember the times in the Army when operators would report shocks from their electric machines. The fix in both cases was to reverse the plug in the socket. OH! for the good ol' days, and only two equally sized blades on a plug.]
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.

Speaking of the 2 wire 'plugs', FWIW, the receptacles were polarized(one wide blade) even though the offending device's plugs were not! When the advent of TV's with 'hot' chassis were created, the wide bladed plugs became common. They had existed, but were rarely used until then.

It is interesting to follow the 'safe thinking' through the creation and replacement of different schemes during the past 50 yrs.

Initially the 3 wire grounded 'system' was de rigor.

Then came the 'double insulated' system.

We are currently near the cusp of the GFCI system.

I hesitate to think what is next!

Each of these 'improved' systems sought to overcome limitations of the preceding one with less than ideal results(hence the perceived need to alter them).

We have succumbed to the utopian dream of achieving total protection. Although a lofty goal, to expect its achievement so as to allow one to totally ignore hazards is foolhardy.

With each succeeding generation, the individual responsibility to handle hazards safely has diminished.

Remember - Don't play with fire! Look(both ways) before crossing the street! Stay away from the stove! Do not operate electrical equipment while standing in water. Do not place your hands near the blades of a cutting device. Do not leave hazardous cleaning chemicals where children can access them. . . .