Loom and the UL inspector

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fifty60

fifty60

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We had a UL inspector a few years back say that we could not use corrugated loom to cover wiring because the loom was not UL approved. Can anyone think of any reason why this would pose any kind of safety hazard?

Does the UL approved wiring become non UL approved if used in a non UL approved loom? I can only think of safety benefits from using the loom???
 
We have wires running from pressure switches and solenoids at the back of the machine to a sub panel located in front of the machine. The wire is concealed behind the machine enclosure. The machines are large, and are between 8-64 cubic feet, so the wire runs can be up to 6 feet or so. What would be the required raceway protection for this? Rigid metal conduit?
 
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The wire gauge is all 16AWG, and are only used for control voltage of 120VAC. We also use the loom for some 24VDC wiring. What would necessitate a different type of conduit? Is split loom even considered conduit? Any direction to rules governing the use of split loom would be greatly appreciated.
 
fifty60 said:
The wire gauge is all 16AWG, and are only used for control voltage of 120VAC. We also use the loom for some 24VDC wiring. What would necessitate a different type of conduit? Is split loom even considered conduit? Any direction to rules governing the use of split loom would be greatly appreciated.
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It is is part of the fixed "internal" wiring of the equipment, it would have to meet UL requirements but not NEC requirements, even if the wiring is on the outside of the cabinet. But the inspector may not understand that.
If the equipment is not designed/tested to any UL standard or if the wiring joins two separate physical boxes, then his position would be a little stronger.
 
loom.jpgThe wiring is connecting pressure switches and solenoids to terminal blocks on a sub panel that connect to a PLC. There is also wiring for customer connections that operate from the PLC. These 20 #16AWG wires are 24VDC, and come from the rear of the machine to the front of the machine where the subpanel is located. There are refrigeration compressors in between the rear and front of the machine, so there is the possibility of moisture.

Not all of our machines are UL. We only use the loom on non-UL machines. I am trying to understand why the inspector did not allow the loom. The only information I have is that the loom did not have any UL markings.
 
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fifty60 said:
The wiring is connecting pressure switches and solenoids to terminal blocks on a sub panel that connect to a PLC. There is also wiring for customer connections that operate from the PLC. These 20 #16AWG wires are 24VDC, and come from the rear of the machine to the front of the machine where the subpanel is located. There are refrigeration compressors in between the rear and front of the machine, so there is the possibility of moisture.

Not all of our machines are UL. We only use the loom on non-UL machines. I am trying to understand why the inspector did not allow the loom. The only information I have is that the loom did not have any UL markings.
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Are these 16ga wires a part of a cable assembly or individual conductors exposed directly to possible physical damage? ...type of cable or conductors? Is the source Class 1, 2, or 3? ...power limited or not? ...any other pertinent facts?

Is the machine for internal company use or manufactured for purchase by a consumer at the location of their choosing? To what standard(s) is the machine design and inspection? To what organization is the inspector affiliated?
 
fifty60 said:
We have wires running from pressure switches and solenoids at the back of the machine to a sub panel located in front of the machine. The wire is concealed behind the machine enclosure. The machines are large, and are between 8-64 cubic feet, so the wire runs can be up to 6 feet or so. What would be the required raceway protection for this? Rigid metal conduit?
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What about PANDUIT?
 
petersonra said:
however just what standard is being inspected to does matter. if it is UL508a, anything outside of the box is probably not covered anyway.
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He said they only use split loom on non-UL machines... so I have to wonder why UL inspector has anything to do with it. Perhaps concerned a non-UL machine will leave the shop with a UL sticker on it... :huh:
 
When you get something UL Listed there is a pre-application presumption that every component of your assembly is UL Recognized or Listed. If anything in your assembly is not UL Recognized or Listed, then you have two options:
1. Pay the expensive fee to have that component tested, wait for the testing, and hope it passes, or,
2. Find something that is already Recognized or Listed and use that.
Most people chose the later but sometimes that's not possible.
 
mgookin said:
When you get something UL Listed there is a pre-application presumption that every component of your assembly is UL Recognized or Listed. If anything in your assembly is not UL Recognized or Listed, then you have two options:
1. Pay the expensive fee to have that component tested, wait for the testing, and hope it passes, or,
2. Find something that is already Recognized or Listed and use that.
Most people chose the later but sometimes that's not possible.
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that is not true at all. there are many things you can use that do not require either listing or recognition in UL listed assemblies. Fasteners come to mind.

and just because something is UL listed or recognized does not mean you can use it.
 
The conductors are mainly 120V class 1 circuits. There are also circuits that I believe would be class 2. They are for a customer connection to our PLC output that customer supplies the power to. The outputs are rated at 24VDC/AC for a maximum of 8A. There are 2 separate circuits for this consisting of 8 wires each. The customer connections are at the back of the machine and we use the loom to protect the wires from moisture and abbrasions as they are ran to the PLC at the front of the Equipment.

The main reason for all of this is that we do not use the loom (whether completely right or wrong) on UL or CSA inspected equipment. We are in the process of CE Marking our equipment and the question of whether or not to use the loom as arisen again. CE is mainly concerned with the end result, and I believe the end result is that the circuits are safer with the loom than without the loom.

I believe UL's problem is that the loom was not listed. My concern is that the wiring would lose it's UL listing if used in a loom, as well as any other concerns I may be overlooking.
 
petersonra said:
that is not true at all. there are many things you can use that do not require either listing or recognition in UL listed assemblies. Fasteners come to mind.

and just because something is UL listed or recognized does not mean you can use it.
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I respectfully disagree with you. They not only test to make sure it's not going to catch fire or electrocute someone, but they check to make sure your components are used within the listed (or recognized) parameters.

If a fastner is not going to hold the intended load and could result in a dangerous condition, they're not going to approve it. What fastners are you speaking of that they don't care about? You can't change out metal fastners for plastic during production without having UL approve it.

The OP has a situation where UL is not approving their conduit to provide protection to wiring; it's a legitimate call. He needs something listed or recognized, or he needs to bear the cost & time to get it listed or recognized.
 
mgookin said:
I respectfully disagree with you. They not only test to make sure it's not going to catch fire or electrocute someone, but they check to make sure your components are used within the listed (or recognized) parameters.

If a fastner is not going to hold the intended load and could result in a dangerous condition, they're not going to approve it. What fastners are you speaking of that they don't care about? You can't change out metal fastners for plastic during production without having UL approve it.

The OP has a situation where UL is not approving their conduit to provide protection to wiring; it's a legitimate call. He needs something listed or recognized, or he needs to bear the cost & time to get it listed or recognized.
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what fasteners are UL listed? ever seen a bolt that says UL on it?
 
What can I do to protect them? If the wires are bound together, would that be considered an assembly, and therefor the split loom would be allowable? Would I need to use a better type of flex conduit?
 
fifty60 said:
What can I do to protect them? If the wires are bound together, would that be considered an assembly, and therefor the split loom would be allowable? Would I need to use a better type of flex conduit?
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There are plenty of options available including various types of plastic raceways or using a cable instead of separate wires.

If you want to make your own cable assembly you would likely need to get UL's blessing on it.
 
The UL inspector raised the issue for some equipment we had inspected. Our normal equipment is not UL. The equipment I am making now is intended for sale in the European market. I am trying to decide whether or not to use the split loom for our prospective CE Marked equipment. Can you please provide replacements for the loom that I can look at?
 
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