GFI Q

[shred]

So I scored a new (well, new in 1938 or so ) 10" Sheldon lathe today. I'm a happy camper. OSHA would not approve. But...

I plugged it into a GFCI outlet and the motor tries to start, then 'click', the GFI pops. This is pretty much the same as when I try to run the air compressor or VFD from that same GFI outlet. All of them work fine on regular outlets.

I've found a bunch of different things online-- some people say motors 'just do that', some say the new GFCIs are fine with motors, some people say it means there's something wrong no matter what. Anybody using GFI outlets in the shop? Seems like a good idea, but not if it can't drive the tools.

 

[Cedge]

GFI's work somewhat like surge protectors. They detect "big" changes in a circuit and do their job quickly to prevent injury. I'd not be all that surprised when they think a starting motor might be a problem. A starting motor creates quite an amperage draw on a circuit before momentum takes over.

Assuming you won't be machining while standing in a puddle, ground fault protexction is not really a plus where typical double insulated tool are in use.

Steve

 

[rake60]

GFI and machine tools just don't work. Their not recommend for household appliances either.

What are the major manufactures saying about GFI's and their appliances?



Amana - Amana appliances require a properly grounded and polarized outlet. Amana does not recommend the use of ground fault interrupter outlets (GFI) with our appliances. The use of this type of outlet may not allow the appliance to operate properly. Some appliance components could create enough resistance to trip the GFI outlet during normal use.

If GFI outlets are required by your local electrical codes, the outlet should be rated at an amperage sufficient for the appliance installed on the electrical circuit containing the GFI.



General Electric - No, we do not recommend GFI outlets with our appliances. GFCI or GFI (Ground fault circuit interrupt) GFI wall plugs check for any current or voltage that may "leak" to the ground. Most appliances have some current leakage to ground, especially electronic gas ranges. The spark igniter on a gas range will cause the GFCI to trip. It is recommended that you NOT plug an electric spark igniter gas range or ANY other major appliance into a GFI wall outlet. This includes: Refrigerators/Freezers, Microwaves/Advantiums, Dishwashers/Disposals, Electric Ranges/Wall Ovens, Gas Ranges (Electric Ignition), Washers, Dryers, Water Softeners, Filtration Systems with Electronic Monitors.



Maytag - Sorry we do not have a recommendation for this type of outlet installation. If you have further questions or comments, please e-mail or contact our Customer Service Department. - phone # section



Frigidaire ~ Electrolux - Thank you for contacting Electrolux Home Products. We do not recommend the use of GFI outlets as they can go bad and cause loss of power to an appliance.

If it won't power the fridge.........

Rick

 

[shred]

Thanks for the extra info.

The typical 'why we don't plug the fridge into a GFI?' I found said that was because they do trip occasionally on motor starts, and if you were out of town, that would be very bad. I could live with occasionally, but every time is pretty annoying. The latest building codes require GFIs in all garage outlets, so we could be in for troubles down the road. When I added circuits to my garage shop, I put GFIs on in order to be compliant and that's one of the circuits I want to use..

Given as how this particular lathe has open flat belts in close proximity to the operator. I'm not thinking 'double-insulated electrical safety' was high on the marketing requirements list either. ;D

I did find one link that says although new motors should be ok on GFIs, older ones leak a little more and eventually cause trips. I think older applies to this one.. looks like it was wound by Edison himself.

 

[PolskiFran]

Hi Shred,
If you are not planning to move the lathe around the garage, it might be wise to permanently wire it to a surface mounted junction box. I have most of my equipment wired to junction boxes.

Some of the older electric motors take a little time to "wind up" and puts a longer draw (amperage) time on the power line.

Hope this helps,
Frank

 

[shred]

Never mind, I got it sorted. Sometimes the GFI really is trying to tell you something useful.

Somebody managed to spectacularly miswire the reverse switch, such that the motor turned when the color coded wires at the wall end matched where they should be, but internally they didn't actually connect to what they were supposed to.

I should have known morons were involved in the past due to the amounts of sawdust in the internals.
anyway now the lathe works on the GFI circuit and I'm a happy camper once again.

Unfortunately I've got too much equipment and not enough room to hard-wire things in yet.

 

[wareagle]

It sounds like shred has his issue solved, but I am going to throw this in here for general information.

There are a lot of misunderstandings about what these outlets really do, and what they don't do. So, here we go. If you already know this, then disregard.

Ground Fault Circuit Interrupters (GFCI) work by comparing the current flow between the hot leg (wire) and neutral or grounded leg (wire). If there is a difference of 6-10mA (I may be off in the value here), then the GFCI will open the circuit. This is a very simple explanation of how a GFCI works, but hopefully you get the idea.

A GFCI does not protect from over current situations, so be aware of this fact. Basically all a GFCI's sole purpose in life is to keep people alive when there is a circuit fault condition causing current to flow from the hot leg to ground outside the circuit. This is how it protects a person from electrical shock.

Refrigerators, electronics, and other appliances have some current "leakage" by design, and therefore the reason why GFCI outlets and breakers shouldn't be used for these applications as illustrated by the things rake60 found on the various websites. Also, miswired equipment will cause a GFCI to trip as in the case with shred.

In order to protect you from electrical shock in the shop, make sure that all of your equipment is properly grounded. GFCI protection is a great idea in the shop, but that is one piece of the protection puzzle. Properly sized over current protection and properly grounded equipment are equally important factors in making for an electrically safe shop environment.

 

[shred]

It sounds like shred has his issue solved, but I am going to throw this in here for general information.

There are a lot of misunderstandings about what these outlets really do, and what they don't do. So, here we go. If you already know this, then disregard.

Ground Fault Circuit Interrupters (GFCI) work by comparing the current flow between the hot leg (wire) and neutral or grounded leg (wire). If there is a difference of 6-10mA (I may be off in the value here), then the GFCI will open the circuit. This is a very simple explanation of how a GFCI works, but hopefully you get the idea.

A GFCI does not protect from over current situations, so be aware of this fact. Basically all a GFCI's sole purpose in life is to keep people alive when there is a circuit fault condition causing current to flow from the hot leg to ground outside the circuit. This is how it protects a person from electrical shock.

Refrigerators, electronics, and other appliances have some current "leakage" by design, and therefore the reason why GFCI outlets and breakers shouldn't be used for these applications as illustrated by the things rake60 found on the various websites. Also, miswired equipment will cause a GFCI to trip as in the case with shred.

In order to protect you from electrical shock in the shop, make sure that all of your equipment is properly grounded. GFCI protection is a great idea in the shop, but that is one piece of the protection puzzle. Properly sized over current protection and properly grounded equipment are equally important factors in making for an electrically safe shop environment.

Thanks for the details. I think I read somewhere the GFCI trip value was 5mA +/- 1mA in my trawling around the net yesterday. Supposedly there are also 'equipment-protecting' (as opposed to people-protecting) GFCIs that have much higher trip values and are designed to protect machines only, but those aren't found at Big Box Hardware, Kitchens & Window Treatments on Sunday afternoon.

I have noticed that grounding is given a lot of lip service in old machines-- sometimes the plug on the end has 3 prongs, but the ground pin doesn't actually connect to anything on the machine. It's an easy fix, but also easy to overlook. If anybody has the slightest doubt, get a multimeter and check. That was my mistake yesterday-- I'd seen the machine run before I got it and was in a hurry to get it up and going, so I just plugged it in without checking.

- Roy

 

[gilessim]

If you don't have an earthtest meter (expensive bit of kit!) there is no way that you can measure how good your earthing is, except to touch a live wire onto the earth wire, if it trips the contact breaker, then you don't have much of an earth, there is no way that you can check an earth with a multimeter ,anyway the only reason for an earth is to protect us from malfunctioning electric motors,or switching apparatus etc.(fairly rare occurrences!) with an efficiently running electric motor, there should be no earth leakage , although saying that,you might get a tingling when you rest your hand on the lathe!.

I'm not saying that an earth doesn't matter, on the contrary, it's very important, but considering that in the States you only have 110v,(as opposed to 220-240v in europe) even if you have the live in one hand and the neg. in the other, it won't kill you! (don't try it though!), basically all I wanted to say was that sometimes the "fear" can be more dangerous than the threat!. If you've got good contact breakers then you're more than halfway there!

BTW if you have an earth pole in the ground and still ,after checking it, you don't get anywhere near zero ohms, there are special "salts" that you mix with water and pour in the hole ,that make an incredible difference to the earthing...hope this helps...Giles

 

[georgeseal]

I built a homemade GFCI tester to check outlets

http://www.codecheck.com/gfci_principal.htm

I think i got the instructions here ( if not I will edit)


George from Conyers Ga

Well maybe I was wrong. Site is still informative so I will leave it

 

[tattoomike68]

The olny place in my house that has a GFCI is in the bathroom.

I did have one on an outside plug but it was a pain, you cant even run a weedeater.

I pulled that peice of junk and put in a plain plug in and have no problems now.

 

[gilessim]

As I tried to say before, maybe I was being a bit obtuse ,but unless you know that you have a decent ground, none of these things are worth even the the materials they're made from, correct me if I'm wrong but I don't believe that US electricity supply companies give you a ground as-well as the pos-neg phases?

 

[shred]

As I tried to say before, maybe I was being a bit obtuse ,but unless you know that you have a decent ground, none of these things are worth even the the materials they're made from, correct me if I'm wrong but I don't believe that US electricity supply companies give you a ground as-well as the pos-neg phases?

Typically in the US, 110v circuit grounds are bonded to neutral at the service panel (breaker box) only. Incoming residential service is 220v single-phase, two hots and a neutral-- from either hot to the neutral is 110v, which is used for nearly everything, and using both gets 220 for the appliances that want that (or in the HSM case, the phase-converter )

Googling 'Neutral ground bonding' will turn up a ton online; it's a common query from those building shops and installing sub-panels.

The multimeter check I suggested before is a simple continuity check between ground and the metal equipment parts, as well as the hot and neutral. It's not a perfect check, but it will tell you if something is miswired or not connected quickly enough.

 

[wareagle]

There is some terminology to understand on electrical systems if you see it, and I will refer to the terms below again, so there is a test <wink>.

• 
  First, there are ungrounded conductors which are your "hot" wires. These are the wires that have the voltage on them (not that this means the others won't have some).
• Second, you have a grounded conductor, which is the neutral wire. This wire carries the unballanced load of the ungrounded conductors, which means there is current (amps) on the neutral, but very little or no voltage. WARNING: This wire WILL KILL YOU if you get between it and and a return pathway to the source.
• Third, you have a grounding conductor, which is your ground wire. It's sole purpose in life is to present a pathway to carry fault currents back to the source of power.

With that knowledge, understanding what the different jobs of each conductor are will become easier. For equipment grounding, it is absolutly essential to have a COMPLETE pathway back to the power source to have a safe electrical system. Earth ground here does not cut it. The circuit breaker or fuse will not open the circuit at the voltages we are dealing with in a residential application.

Why? The earth has a typical resistance of 25 ohms. Take an ungrounded conductor that is energized and ground it to earth. The circuit breaker or fuse will not open the circuit. Do a little ohms law calculation: Take your voltage and divide it by the resistance, and this will give you the current. As follows:

110 volts / 25 ohms = 4.4 amps
220 volts / 25 ohms = 8.8 amps

As you can see, these values are not close enough to the rating of a 15A or 20A breaker to open the circuit under a fault condition. Take the same numbers, and then put the human body in the circuit. It takes less than one amp to incapacitate and kill a human being!

As you can see, it is very important to ground you machinery and to make sure your electrical system is in proper working order.


The use of this information is at your own risk! The responsibility to thoroughly understand the proper methods of installing and maintaining electrical systems should not be taken lightly. If one is in doubt, has questions, or concerns, then consult the expertise of a qualified electrician. The above is for informational purposes only, and the author is not liable for any use of the above information.

Edited to add subscript.

 

[Julian]

Hi Guys,

My whole house is protected by circuit breakers on the main board with different ratings for different circuits. My board also has a side controlled by an RCD. My workshop is wired thru this and a 40 amp breaker. With the loads we all tend to pull in the shop make sure you have a ring main for the sockets and run the lights from another trip or circuit. If you trip the sockets you can still see to a. find it and trip it back and b. get out the shop without tripping yourself over or cutting yourself. I also have a ground earth pole outside in the ground. The advice given to me years ago by an electrical engineer is get a long one and whack it in the ground as far as you can. You want it to go hopefully down well into the water table because this is where you get the best earth connection into the rest of the earth. My water table is only 2ft down but the pole is 6ft with the cable soldered on the top.

Nothing in my shop trips the breakers except the new Mig welder. When it is on its top setting it blows its own 13amp fuse just as you release the trigger. Apparently it is because of the shock of stopping. They reccomend a 20amp fuse as on full power it pulls 15amps. Can't get any household plug fuses for over 13amps so drilled thru the end caps of a blown one and soldered in a length of 20amp fuse wire....sorted. I find that any fuse or bulb blowing in the house will open the trip it is connected to but it allows a faulty motor on the washer to continue running!!

Julian.