Operating Temperature of Twistlock

[ron]

Is anyone familiar with formal documentation regarding the acceptable maximum temperature allowed for the body (exterior) of a 20A 1 phase twistlock? I realize the terminal temperature rating may be 60 or 75 degrees C, but how might that reflect itself on the portion of the body that an operator would touch when run at full rating (16A).

 

[mgookin]

A little more context to your question (and a part #) would go a long way.
For example, this Hubbell product is rated as follows:

Operating Temperatures

Maximum Continuous 75 C

http://www.hubbellcatalog.com/wiring/section-b-datasheet.asp?FAM=Locking_Devices&PN=HBL9965C

We manufacture products with a rated ambient operating environment of 80C (176F) but that does not mean I'm going to reach into the environmental chamber during testing and touch it with a bare hand.

Do you have an existing installation where something is getting hot? If so, is it failing or deforming?
Are you trying to come up with a solution for an environment with high temp?

 

[don_resqcapt19]

I have seen so many failures of field installed cord connectors from excessive heat that I am beginning to think that the wire terminations are not really designed for use with the finely stranded conductors that you find in flexible cords.

 

[ADub]

I have seen so many failures of field installed cord connectors from excessive heat that I am beginning to think that the wire terminations are not really designed for use with the finely stranded conductors that you find in flexible cords.

Agreed. We avoid twistlock cord connectors like the plague. It is just a never ending revolving door of replacements


Sent from my iPad using Tapatalk

 

[ptonsparky]

Bigger is better in this case.

 

[mopowr steve]

I have seen so many failures of field installed cord connectors from excessive heat that I am beginning to think that the wire terminations are not really designed for use with the finely stranded conductors that you find in flexible cords.

I completly agree with you, it always seems that the deformation of OEM cord ends and replacements comes from the internal connection. Hope someday NEMA sets the standard for these terminations to be made with wire size up one to combat the problem or other remedy.

 

[JFletcher]

I wonder how many twistlocks get abused more than regular cords? A great number of people remove cords by yanking them out by the cord and not firm removal of the plug, and ofc a twistlock will just get stressed by this action instead of coming out. The wire is the same in either one. Or is there another reason they are failing? From what Ive seen, field made cord ends have to be done perfectly to be right.

 

[ron]

A little more context to your question (and a part #) would go a long way.

This is a data center with a somewhat generic looking L5-20 plug and connector body serving a IT rack. The operations staff indicates the plug and connector body are warm/hot, but has not told me the actual temperature yet, just that it is close to but below its continuous rating of 16A. The load profile is pretty flat, so I would guess it is hanging around at 15-16A 24/7.

If the terminations are good for 60deg C, what is an acceptable temp on the outside of the plug or connector body when I have an IR scan done?

 

[ron]

This is a data center with a somewhat generic looking L5-20 plug and connector body serving a IT rack. The operations staff indicates the plug and connector body are warm/hot, but has not told me the actual temperature yet, just that it is close to but below its continuous rating of 16A. The load profile is pretty flat, so I would guess it is hanging around at 15-16A 24/7.

If the terminations are good for 60deg C, what is an acceptable temp on the outside of the plug or connector body when I have an IR scan done?

BTW, it is not failing or deforming, yet. We don't know what an alarming temperature should be.

 

[kwired]

This is a data center with a somewhat generic looking L5-20 plug and connector body serving a IT rack. The operations staff indicates the plug and connector body are warm/hot, but has not told me the actual temperature yet, just that it is close to but below its continuous rating of 16A. The load profile is pretty flat, so I would guess it is hanging around at 15-16A 24/7.

If the terminations are good for 60deg C, what is an acceptable temp on the outside of the plug or connector body when I have an IR scan done?

You possibly have harmonic currents adding to the problem if it is data center equipment. And the thing may have fairly continuous load 24/7. Most the plug/receptacle combinations that I encounter are not continuously loaded and often are supplying motor loads as the main power user.

 

[ron]

You possibly have harmonic currents adding to the problem if it is data center equipment.

I agree although this is a 120V circuit with dedicated neutrals per circuit, so no triplens adding up, just regular harmonics.

I'm trying to find some formal document from some manuf or standards agency that would indciate an acceptable outer body temperature for the device.

For example, Lutron comes out themself in a document that a dimmer will be "warm".

Operating on its rated load, Lutron dimmers will stay below the UL limits of 140º F (60º C).

 

[iwire]

Ron, I cannot answer you question directly but my experiance seems to jive with others.

TLs will not last when operated 24/7 at even 80% load.

I rewired a large portable amusement ride and used 20 amp TLs to drive incandescent lighting. I loaded each 20 amp TL up to 14-15 amps and withing a few weeks they where burning up.

I was very disappointed.

If this load you are dealing with is critical maybe change to a pin and sleeve style set up like a Meltric device.

 

[big john]

I have a theory that cord-weight on horizontal TLs causes a lot of uneven contact pressure in the current path and results in high resistance.

Vertical mounted TLs are much more rare, but I've never had one burn up.

Anyone seen something similar?

 

[mgookin]

This is a data center with a somewhat generic looking L5-20 plug and connector body serving a IT rack. The operations staff indicates the plug and connector body are warm/hot, but has not told me the actual temperature yet, just that it is close to but below its continuous rating of 16A. The load profile is pretty flat, so I would guess it is hanging around at 15-16A 24/7.

If the terminations are good for 60deg C, what is an acceptable temp on the outside of the plug or connector body when I have an IR scan done?

The answer to that is "so hot that if you touch it you'll get burned".

Here's another datasheet: http://www.legrand.us/~/media/produ...gs connectors 3 wire spec sheet sf1702r2.ashx

As you can see, Temperature Rise is 30C max @ 150% rated current.
30C=85F
If your room is 75F that's 75F+85F=160F. That's so hot that anyone touching it would be burned. Granted you're not loading it at 150% rated current but let's agree that any load will cause temperature rise. According to NIST even at 111F a human feels like they're getting burned.

Some things you can consider:
Check your connections and wiring. Bad connections & wiring are the #1 cause of heat at a plug.
Go with a plug with a higher amperage rating.
Provide strain relief.
Hardwire the circuit.

 

[GeorgeB]

As you can see, Temperature Rise is 30C max @ 150% rated current. 30C=85F

That old degrees C versus C degrees. 1 Celsius degree is 1.8 Fahrenheit degree; 30C rise == 54F rise

(0C==32F) ... ???

 

[mgookin]

That old degrees C versus C degrees. 1 Celsius degree is 1.8 Fahrenheit degree; 30C rise == 54F rise

(0C==32F) ... ???

You got me!

It made sense to me because our stuff (which is twist lock) is rated 80C (176F) and I'm not touching that at those temps.

Thanks for the heads up.

So that puts him at 129F. Still very hot to the touch.