Equipment Grounding - Not What You Might Expect
Wiring Dryer to the Manufactures Instructions
November 13, 1996 - Mike Holt purchased an electric dryer from Frigidaire. The instructions were included with the dryer. I don't normally read electrical instructions (it's a man thing) but I thought that since I always tell people in my seminars that they need to be sure to comply with the NEC Section 110-3(b) which states: "Installation and Use. Listed or labeled equipment shall be installed, used, or both, in accordance with any instructions included in the listing or labeling." I thought, what the heck, I would read the instructions.
That's where this story begins. The instructions that were supplied with my Frigidaire dryer [model number ME3436RBW1, serial number XD60389474] [P/N 131411400 (10/94)] contains (what I believe) three errors.
Concern No. 1 (NEC Code Violation)
Page 6 on the bottom right, instruction No. 7 specifies that when you have a 4-wire system you "Attach the white (neutral) power cord conductor from the power cord and the green ground wire from the dryer harness to the silver-colored center terminal on the terminal block."
Comment: What they are saying is that when you wire the dryer with a 4-wire cord, they want you to tie the dryer ground and neutral from the power cord together at the dryer neutral terminal. I believe that this violates NEC Sections 250-60 and 250-61.
Concern No. 2 (NEC Code Violation)
Page 7 top left graphic demonstrates the green ground wire from the dryer harness connected to the center (neutral) terminal are specified in Error No. 1 above.
Concern No. 3 (Death/Shock Hazard)
Page 7 on the left side of the page under the heading Grounding Requirements contains a danger notice: "Improper connection of the equipment grounding conductor can result in a risk of electrical shock. Check with a licensed electrician if you are in doubt as to whether the appliance is properly grounded."
I have no problem with the above statement, however on the same page on the bottom right, Instruction No. 5 under Grounding Requirements, it says that if there is no ground for the dryer, or if no grounded water pipe is available to ground the dryer, a ground rod MUST be used and register no more than 25 ohms resistance when in the ground. Drive the rod into the ground outside the dwelling and connect a grounding wire (12 AWG or heavier) between the grounding screw and the grounding rod. It may take more than one ground rod to not exceed 25 ohms resistance to ground."
Comment: If we followed these instructions and use a ground rod of 25 ohms, and there was a ground fault to the dryer case, the maximum fault current that would travel through the protection device would be 4.8 amperes (I = E/R, I = 120 volts/25 ohms). This will not cause the 30 ampere protection device to clear the fault, and the home owner won't know that his/her family could get killed by simply touching the energized dryer case!
November 13, 1996 - I contacted Frigidaire about their instructions. After about 4 hours, six phone calls and a bunch of run-a-rounds, I decided to call the President of Frigidaire. I spoke to his secretary (Connie) and she had a Mr. John Martin return my call. He was very polite and allowed me to explain my concern about their instructions. He appeared to be interested and said that he would investigate and contact me the following day.
December 18, 1996 - John Martin did not contact me about this subject yet, so I called the President of Frigidaire and spoke to Connie again, I explained that I really felt that their instructions were in violation of the NEC and in some cases could result in the risk of electrical shock and death of their customers.
December 19, 1996 - John Martin (1-614-792-4843) left the following message on my voice mail ( I have a copy of the audio tape): "I have again reviewed this with legal and the Code man at the appropriate plant. They both assure me that what we are putting in print is probably the same thing that we have done for many years and UL has not contacted us about this. The paper work is part of the safety survey which is okayed by UL and we're standing pat. What we have is acceptable to UL and it has been reviewed and acceptable to the plant. Don't know what else to say....."
December 19, 1996 - Left a message with John Martin's voice mail that felt that their instructions were hazardous and that I would contact UL and the NFPA. I explained that I would keep him informed and that I would post this on my Internet site.
December 20, 1996 - Contacted UL, and spoke to Mr. Paul Duks (one of the Vice Presidents and really great guy) and he asked me to fax him a copy of the dryer instructions. Which I did. His comment based on my conversation was that the grounds and neutral should not be tied together at the dryer and should be separated according to the NEC. Mr. Duks also agreed that driving a ground rod of 25 ohms would not be an appropriate method of grounding the dryer, since this was not an effective low impedance path at required by NEC Section 250-75. Mr. Duks indicated that he would keep me informed on his investigation of this issue.
December 20, 1996 - I faxed a copy of the above information to Mr. Mark Ode at the NFPA for his opinion.
Comment: I don't feel that the errors in Frigidaire's instructions for dryers are probably any different than the instructions for their ranges and ovens. In addition, I bet that most (all) manufactures instructions that supply ranges, dryers and ovens have the same errors and that this is an industry wide problem. As a matter of fact I bet, the instructions of a "25 ohm ground rod - last resort ground" is probably contained in the instructions of many different types of instructions.
How you can help. Please review the wiring instructions for ranges, dryers, ovens, and all other equipment and let me know if this is an isolated incident or if this is an industry wide problem. E-mail your information to me at email@example.com. If you can, provide me with the manufacture name, the model number, the serial number, and the appliance type. If you have any comments, I can be reached at 1-800-881-2581.
December 21, 1996 - Posted this on the Internet.
I really wonder, is it possible that UL has permitted equipment manufacturers instructions to use a 25 ohm ground rod as an acceptable last resort grounding method? Wouldn't it be better simply to say the equipment must be grounded according to the NEC and that it be accomplished by a qualified electrical contractor, inspected by a qualified electrical inspector?
Am I going to upset some people by having this on the Internet? Is some lawyer going to be sending me a letter soon? Am I right? If I am, how long has the instructions been wrong? 2 years? 5 years, 30 years? Did I open up a can of worms?
Why did I have to read the instructions anyway...............
December 25, 1996 - Merry Christmas and Happy Birthday - Jesus.
January 3, 1997 - Received a call from Mr. Fred Pauk (Safety Administrator for Frigidiaire Appliances) and he explained that after consulting with their engineers, that the ground wire in question was not actually a ground wire, but is the link from the neutral terminal to the case ground (for three wire systems). When the dryer is installed with a four-wire system, this neutral-to-case bond wire is to be removed from the case and is simply connected back to the neutral terminal and serves no purpose. Mr. Pauk also indicated that after reviewing their instructions and graphics, that they plan on revising them to clarify that the green wire is a neutral-to-case bond wire. Mr. Pauk is searching why the instructions indicated the use of a ground rod for grounding. He believes that this is a UL requirement and will get back to me on this.
January 6, 1997, 10 AM- Received a call from Mr. John Martin and he confirmed Mr. Pauk's comments. He also faxed me a copy of the wiring diagram. I check the wiring diagram and the wire that they call the green ground wire is indeed a neutral-to-case bond wire. I apologized to Mr. Martin for giving him a hard time on these issues.
Comment: Well that answers my concerns for No. 1 and No. 2, but we still have the issue of using a ground rod for grounding the dryer. I'll keep you informed.
January 6, 1997 4 PM - Received a call from Mr. Pauk and said that there is no UL standard to use the ground rod for grounding. Mr Pauk has indicated that they are in the process of revising their instruction book to remove the text of using a ground rod for grounding.
January 6, 1997, 4 PM - Left message with Mr. Chuck Williams (UL) to find out why UL permitted the improper instruction text on grounding to be in the instruction book in the first place.
January 13, 1997, 3 PM - Received a call from Mr. Don Shaw (UL) and he "opened-a-file" on my complaint of Frigidaire's dryer instructions. I explained that I have been in contact with Frigidaire and that they were revising their instruction manual. I ask him if UL would be investigating all of their standards to insure that when they review the instuctions that they were safe and correct. He said that he was only investigating the Frigidaire instruction booklet. I asked who I could speak to about all of the other products to insure their correctness, he said that he would have a Mr. Don Grob (Heading of Dryer Engineering) contact me.
January 22, 1997 - Received a letter from Mr. Edie Spielman (Engineering Aide) acknowledges my fax sent December 20, 1996 to Mr. Paul Duks. They are reviewing the information and appropriate action will be taken in the near future.
March 26, 1997, 6 AM- Boy how time flies. I've been traveling so much lately, that I haven't had time to call and find out what's happening on this subject. Going out of town again today (Orlando), but at least it's with the family for 10 days to just have fun and relax. I'll try to call UL this morning before I leave.
April 7, 1997, Called UL asked about the progress of my concerned. Spke to Mr. Shaw, who said that he spoke to a Mr. Loyd England (I think thats the spelling) in the hall last Friady (April 4, 1997). He said that Mr. England is in the process of reviewing all standards. I don't know if this is true, but that's the latest word.