Brian,
The use of wire nuts on short wire pigtails in a wiring box for connection to the building wiring is primarily a North American wiring method. You can deduce this by looking at the marks on the box that they came in. They most likely have listing marks for the US, Canada, and/or Mexico, and wire sizes are in “AWG”. If, on the other hand, you saw the CE Mark or wire sizes posted in “mm2”, or some other international certification markings, you would have evidence that the use of those wire nuts is an acceptable wiring method elsewhere. More evidence of this can be seen in national deviations found in Annex NAE of UL 60950-1/CSA C22.2 No. 60950-1 vs.the group deviations of EN 60950-1. UL/CSA 69050-1, Annex NAE 3.2.3 describes leads for field wiring connections to be not smaller than 150 mm (6 inches) in length, making reference to sections of the National Electrical Code and Canadian Electrical Code, Part I. Annex NAE 3.2.9 further describes box volume calculations required by the NEC and Canadian Electrical Code for the number of conductors being connected in a wiring box, normally by wire nuts. On the other hand, EN 60950-1 has no such deviations or notations. However, written into the body of the IEC 60950-1 and EN 60950-1 (and other national derivative standards) is a wiring method for permanent connection to the mains not acceptable in the US and Canada – the use of a non-detachable power supply cord for permanent connection. The most universally accepted means for permanent connection to the mains is to use a field wiring terminal block with a current rating 125 % of the current rating of the product it is installed in, certified for the country of deployment. In conjunction, holes should be supplied nearby for accommodation of a conduit system or cable-securing glands. Best Regards, Don Gies, N.C.E Senior Product Compliance Engineer Alcatel-Lucent Murray Hill, NJ 07974-0636 USA ________________________________ From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: Monday, November 17, 2008 3:53 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: What's the deal with Wire Nuts? Scott, Does the 60950 standard give examples of what would satisfy the “two independent fixings” requirement? How would a terminal block satisfy this? I have heard that a wire nut can be used for the electrical connection, but you have to also mechanically hold the wires together which can be done with a cable tie. No where have I found this documented, though. The Other Brian ________________________________ From: scott barrows [mailto:sbarro...@yahoo.com] Sent: Monday, November 17, 2008 2:50 PM To: sbarro...@yahoo.com; Ted Eckert; EMC-PSTC@LISTSERV.IEEE.ORG; Aldous, Scott; Kunde, Brian Subject: RE: What's the deal with Wire Nuts? Hello Other Brian, That is a term I have heard from years gone by. A standard does not specifically prohibit them however if you look at IEC 60950 para 3.1.9 it would be difficult to use wire nut that met the requirements of "two independent fixings". Most EU standards have a similar discription as well. Best Regards, Scott --- On Mon, 11/17/08, Kunde, Brian <brian_ku...@lecotc.com> wrote: From: Kunde, Brian <brian_ku...@lecotc.com> Subject: RE: What's the deal with Wire Nuts? To: sbarro...@yahoo.com, "Ted Eckert" <ted.eck...@microsoft.com>, EMC-PSTC@LISTSERV.IEEE.ORG, "Aldous, Scott" <scott.ald...@aei.com> Date: Monday, November 17, 2008, 2:31 PM Where does the term, “Redundant Captive Device” come from? The device which has the wire nuts (twist-on wire connectors) is a water chiller used as a peripheral for a piece of laboratory equipment to be sold internationally. The manufacturer is not used to making laboratory equipment, but industrial cooling devices in the US where it maybe acceptable to use wire nuts. Looking at the IEC/EN 61010-1 standard I cannot see any specific requirement for redundant captive device or redundant connection. I do see a statement in 10.5.3b regarding “insulation which supports the TERMINALS shall be made of material that will not soften” due to dissipated heat from current through the connection. I assume that if the plastic cap of a wire nut gets hot from current passing through the connection and softens then the connection will become loose. Some wire nuts are all plastic and the larger ones have a copper spring inside. In either case, it is the plastic that secures the connection. On a crimp type connection (such as a spade lug or crimp splice), even though they have a plastic case, the electrical connection is made from a metal part which is not likely to soften. It would be nice if there was a clear statement (chapter and verse) documenting if wire nuts can be used in Europe or not or some kind of interpretation letter. The Other Brian ________________________________ From: scott barrows [mailto:sbarro...@yahoo.com] Sent: Monday, November 17, 2008 12:26 PM To: Ted Eckert; Kunde, Brian ; EMC-PSTC@LISTSERV.IEEE.ORG; Aldous, Scott Subject: RE: What's the deal with Wire Nuts? It is not a redundant captive device. Scott --- On Mon, 11/17/08, Aldous, Scott <scott.ald...@aei.com> wrote: From: Aldous, Scott <scott.ald...@aei.com> Subject: RE: What's the deal with Wire Nuts? To: "Ted Eckert" <ted.eck...@microsoft.com>, " Kunde, Brian " <brian_ku...@lecotc.com>, EMC-PSTC@LISTSERV.IEEE.ORG Date: Monday, November 17, 2008, 12:08 PM Hi Brian, When I worked for UL, I had heard that the use of wire nuts was not acceptable for the EU (CE Marking), but I don’t recall ever seeing the source of this alleged requirement. I have a vague recollection about them not having any type of international certifications, but I’m not sure about that. There is a book, CE Marking Handbook: A Practical Approach to Global Safety Certification, by David Lohbeck, published in 1998, which covers this, but not in depth. You can preview the book on Google. On page 119, that book indicates that “ U.S. wire-nuts are not permitted for wire connections.” I don’t believe the source of this statement is provided, and it well may just be the opinion of the author. Scott Aldous Compliance Engineer Advanced Energy Tel: 970-407-6872 Fax: 970-407-5872 ________________________________ From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Ted Eckert Sent: Monday, November 17, 2008 9:39 AM To: Kunde, Brian ; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: What's the deal with Wire Nuts? Hello Brian, Off hand, I am unaware of anything preventing the use of a twist-on wire connector in portable equipment, but that doesn’t mean that the prohibition doesn’t exist. Other list members may know of specific cases where the connectors are prohibited. However, the description of the connector covered in electrical tape indicates that the connector is likely used outside of its UL Listing (if it is even a Listed connector.) First, let me state that “Wire-Nut” is a registered trademark of Ideal Industries. If you are looking for information in standards, the term “twist-on wire connector” will be used. Vibration during use is probably not the main issue. There are many types of fixed equipment, such as an air conditioner or other motor driven appliance, where twist-on connectors are used and they are subject to regular vibration. The connectors may see more vibration in these applications than they might see in some portable appliances. However, your description gives me cause to be concerned. UL does List twist-on connectors under category code ZMVV and they have been around for quite a while. (Ideal’s UL file number is E5238 and that should give you an idea as to the age of the product.) The connectors’ Listing does have some very specific requirements. Specific size connectors are Listed only for use with specific wire sizes and types. The installation instructions must be followed closely. Some of the wire connectors specify that you should not twist the wires first. The twisting of the wire connector will twist the wires to make the proper connection. If you see a connector covered with black tape, there is likely a problem. The tape is typically used when there is a concern that the connector will come loose. This is done based on the installer’s experience. If they have had connectors come loose, it is because they are likely using them incorrectly. The tape does not fix anything. Electrical tape will not likely withstand the test of time and the adhesive will degrade. Cheap electrical tape rarely lasts long at all. There are numerous crimp connectors suitable for connecting wires. There are but splices and crimp connectors designed to perform the same purpose as a twist-on connector. The crimp connectors make a good, permanent splice. The twist-on connector is intended for use where connections are made in the field, particularly where they may need to be undone for servicing. Crimp connections and terminal blocks are better options for factory connections. Ted Eckert Compliance Engineer Microsoft Corporation ted.eck...@microsoft.com The opinions expressed are my own and do not necessarily reflect those of my employer. From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: Monday, November 17, 2008 6:18 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: What's the deal with Wire Nuts? Greetings Experts. This should be an easy one for those who know the answer. What is the deal with Wire Nuts? Where can be they be used, where can’t they be used? Are there different rules for permanently mounted equipment verse portable equipment? Do you have to also use a mechanical device such are a tie wrap? How about black tape? Our company does not use wire nuts but we always had the impression that safety inspectors do not like to see wire nuts in portable equipment. We are evaluating a product made by another company that uses wire nuts on primary wiring with black tape wrapped around it. Is this technique acceptable internationally on portable equipment? Thanks to all in advance for the education. The Other Brian _________________________ LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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