Motor Lead Wire
Motor Lead Wire
(OP)
I was wondering if there was a limitation to how long leads could be on a motor?
Can they be run in conduit?
Are there any standards for this?
Thanks in advance,
Can they be run in conduit?
Are there any standards for this?
Thanks in advance,





RE: Motor Lead Wire
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Motor Lead Wire
You would surely want to think carefully about doing anything different. Typically different types of wires are used in each application. Finely stranded for motor lead wire... often with minimal mechanical armour, absolutely no shielding for lead wire (medium voltage). Also what benefit could there be to terminating anywhere other than motor term box? What happens when you swap the motor?
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
I was wanting to know if the NEC does govern this?
What kind of problems exist?
Will i have to up size the wire?
So on.
RE: Motor Lead Wire
RE: Motor Lead Wire
This sounds like a kiln application.
Submersible pumps use very long motor leads.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Motor Lead Wire
Otherwise, I do not know of any restriction that prohibits the motor leads from passing through the terminal box, into the conduit, and on to another connection point 30 feet away. Of course, it would be a real pain to pull the leads through the conduit each time you changed the motor.
RE: Motor Lead Wire
http
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
Time was when lumber kilns had propeller fans mounted directly on the motor shafts. Ambient temperatures during operation could exceed 100 deg C. The motors were specially built for kiln duty. Connections to the motors was always a problem. Many installations used mineral insulated cable to feed the motors.
Long motor leads would allow the motor connections to be made outside the kiln where normal wiring methods could be used.
Many kilns now have the motors mounted outside the kiln and use belts or a drive shaft to drive the fans.
Back in the day of inside the kiln mounted motors, I would have liked 30 Ft. long motor leads.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Motor Lead Wire
electricpete, I do not see anything in those tables regarding conduit. Perhaps you can enlighten me. If there is a reference to conduit then I guess I'll need to check the markings on our lead wire to see if it meets the specifications in your reference and, if not, I'll need to retract the statement that there may be no problem with pulling lead wire through a conduit.
Otherwise, I think waross has nailed the answer. Of course, if the OP isn't sure about the reason or the correctness of doing so, all he needs to do is ask the customer for clarification of his request per my suggestion.
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
One common design had the fans on ten foot centers in a line down the center of the attic space above the fan deck.
8' leads would allow connections to be made above the roof outside the kiln. Good.
15' leads would allow the connections to be made at ceiling ("fan deck" in dry kiln terminology) level outside the kiln. Better.
30' leads would allow connections (and trouble shooting) to be done at ground level outside the kiln. Best.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Motor Lead Wire
For electricpete, I wasn't asking you to enlighten me on the whole of UL or the NEC. I was simply asking for you to point out the part in the tables of the reference that applied to conduit or to motor lead wire. I could not find anything there and thought that I was missing something.
By the way, the lead wire we use for low voltage motors is EPDM, 600V, 150C, UL3340/3374. In either case, I agree that before anyone starts pulling motor lead wire, or any other type of wire, into a conduit that they should be certain that it meets all applicable local codes for the type of installation they are doing.
RE: Motor Lead Wire
One thing I do know is that NEC does not apply to the motor lead function. So, it is certainly possible and plausible that motor lead wires do not meet the specific UL listing requirements associated with the various NEC paragraphs. We are in agreement that it needs to be verified.
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
Table 310.64 applies to 600vac and below. It lists cable type using terminology similar to the first column of the link above... doesnt' really help. But I listed it here for historical reference.
A more relevant link is here:
htt
I think your 3340 and 3347 are "style numbers" for AWM.
So what does AWM mean?
htt
Example:
http://www.wcwc.com/053818/specsheets/pdf/epdm.pdf
So from my bit of research using google I am inclined to think UL 3340 / 3374 is a niche cable intended for use as part of appliances, but not specifically intended for field use.
I am under the impression that cables have a very wide degree of differentiation/specialization (look in a cable catalogue or website for bewildering variety). We choose the cable designed for the purpose we have in mind. What exactly would not work about this lead cable I don't know other than the compliance aspect. We already talked about ampacity... that depends on how the cable is installed. Also NEC has requirements related to damp locations, wet locations. Sometimes there are other requirements on the fire resistance or smoke resistance of cable (I'm not sure if I have those terms right). And more that I am not in the least familiar with.
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
David Castor
www.cvoes.com
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
http:
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
In general, once the conductors leave the motor TJB, they are in NEC land. Inside the motor and TJB, they are exempt from most NEC requirements for wiring. At least that is always how it has been in my experience.
David Castor
www.cvoes.com
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
You have correctly identified the wire that we use since it does have the AWM marking and you have also in the process enlightened me on what AWM means. You have also shown that the NEC states that a motor junction box shall not be more than 6ft from the motor.
However, if I read your posts correctly, you have quoted that "AWM has not been evaluated for general wiring applications in accordance with the NEC." I read this to mean that they have not formed an opinion or, more specifically, that they have not endorsed this use nor have they prohibited it.
Finally, I am wondering, if you say this in your 3/6 21:41 post:
and this in your 3/7 21:10 post:
and this in your 3/7 18:26 post:
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
...then why are you now offering advice on the NEC and UL?
electricpete...I obviously hit the 'submit post' button while still editing since I have a quoted you twice with different date/time entries that are erroneous (3/7 18:26 is the correct one). However, the quotes are from this thread. I do not mean to be harsh, especially considering that I complimented you so profusely last night on a different thread.
My point is that anyone can do a 'google search' on a topic and provide quotes from that search whether they fully understand the subject or not. If you are not fully proficient in what you are posting, then you are not offering any more information than the people that come here for help can find on their own doing their own 'google searches' if they are interested in that source of information.
If you simply have a lot of time on your hands (which some people like myself don't but you apparently do) and you can perform 'google searches' to offer information that applies to the question at hand, then you should be very careful to note that you are not an 'expert' but are simply offering information that you have found by searching the internet.
RE: Motor Lead Wire
Sorry, but sometimes you come across quite strong with your opinion when it is obviously based on recent internet research and not actual working experience.
At the same time I will say that sometimes your real strengths shine through brilliantly.
RE: Motor Lead Wire
Then, you took this one single thread and tried to weave it into an insinuation that the bulk of my participation in eng-tips is involved with googling things that I know nothing about. I can tell you, I am familiar with the postings of electricpete. The vast majority of my initial responses come straight from my head. I generally only go to google when there begins to be a disagreement and I think there is proof of a point I have made, or when there is a point that comes up that I am unsure of and would like more information, or when I have information available to me in a book that I know can be shared by googlebooks.
I agree I spent a lot of time on eng-tips this weekend, probably more than I should have based on other stuff I should attend to. It is fun for me and sometimes I overindulge. But that is really none of your concern.
I would encourage you to contribute from your considerable knowledge working in motor repair, but don't waste your time critiquing the contributions of others.
I looked two sets of removed T-lead souvenirs in my garage (one had insulation swollen due oil, another associated with a failure). Imprinted on the swollen one is is AWM style 3499. If I knew what 3499 meant, I could tell you that style is susceptible to oil problems. The other had no markings related to AWM or other UL or NEC recognizeable markings. The AWM marking is optional as I read recently. I have a few more T-leads at work that I'm going to look at. But from these first few data points, I suspect AWM T-leads are common. I would love to have a decoder list for that 4-digit style number to help me figure out and confirm what materials are used on our various motor leads. Google didn't find it for me. But if anyone can find it by google or otherwise, I'd be appreciative.
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Lead Wire
It's not a Belden code by any chance? Their type codes are typically four digit and the range is enormous.
Page 2 of this link shows Belden style 3499. And I ain't an expert on Belden codes, before anyone thinks I am. This came via Google.
----------------------------------
If we learn from our mistakes I'm getting a great education!
RE: Motor Lead Wire
=====================================
Eng-tips forums: The best place on the web for engineering discussions.