Splicing 24 VDC Signal Wiring

[BFritz]

I have a piece of equipment with a control panel mounted to the side of it. The 24 VDC signal wire from a level sensor located on the far side of the equipment could not reach the control panel so our technician spliced the multi-conductor cable's conductors and heat shrinked the whole splice. I believe he soldered the connections and heat shrinked individually as well.

Is this acceptable per NEC? This is not in a raceway, it is along the framework that the cable is tied to. I'm not sure that NEC covers this specific area, especially as it pertains to 24 VDC signal wires.

Thank you

 

[petersonra]

Let me ask you a question first. How is it that such an installation is NEC compliant in the first place. My guess is that the answer is going to be that it is a Class 2 circuit. Ask yourself if there is any prohibition on making a spice or a connection in the open with class two circuits.

 

[retirede]

If this wiring is part of the equipment assembly, NEC likely does not apply.

 

[SceneryDriver]

I have a piece of equipment with a control panel mounted to the side of it. The 24 VDC signal wire from a level sensor located on the far side of the equipment could not reach the control panel so our technician spliced the multi-conductor cable's conductors and heat shrinked the whole splice. I believe he soldered the connections and heat shrinked individually as well.

Is this acceptable per NEC? This is not in a raceway, it is along the framework that the cable is tied to. I'm not sure that NEC covers this specific area, especially as it pertains to 24 VDC signal wires.

Thank you

I've done this type of repair before; it's often the only real way to repair some cables when there's no space/provision for a j-box. As long as the solder joints are done correctly and there are no cold joints, it's fine. Sounds like he did it right; soldering, individual heat shrinking, and overall heat shrinking. Other than it appearing slightly lumpy, it's fine. If there's any chance of liquid intrusion, adhesive-lined heat shrink should be used on the overall cover, and it should overlap the cable jacket by a healthy amount on each side.


SceneryDriver

 

[BFritz]

I just found out that the technician crimped the wires together. He did not use solder. Heat shrinked each crimp. Then heat shrinked over everything.

 

[GoldDigger]

I just found out that the technician crimped the wires together. He did not use solder. Heat shrinked each crimp. Then heat shrinked over everything.

Many feel that a properly made crimp (using a full cycle tool) is preferred to soldering for most purposes.

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[petersonra]

Many feel that a properly made crimp (using a full cycle tool) is preferred to soldering for most purposes.

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I am inclined to agree that a controlled cycle tool probably makes a better connection than solder. however the solder connection is more than adequate especially for something like this where there is virtually no current flow.

 

[GoldDigger]

I am inclined to agree that a controlled cycle tool probably makes a better connection than solder. however the solder connection is more than adequate especially for something like this where there is virtually no current flow.

Quite true, if the connection is made mechanically, e.g. by twisting, before soldering. And if the shrink gives proper strain relief past the soldered region.
Stranded or solid wire?

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