Does a splice inside a Safety Disconnect Switch Box meet NEC standards?

[BoilerBB]

I am trying to verify that a small to mid-size piece of industrial equipment is in NEC compliance while making wiring changes to meet the installation requirements for a UL listed component. The safety disconnect switch box used on the piece of equipment is only UL listed for 14 AWG wire and larger. The equipment is wired with all 16 AWG wire into the switch box. NEC section 312.8 Switch and Overcurrent Device Enclosures Section A reads as follows:



“(A) Splices, Taps, and Feed-Through Conductors

The wiring space of enclosures for switches or overcurrent devices shall be permitted for conductors feeding through, spliced, or tapping off to other enclosures, switches, or overcurrent devices where all of the following conditions are met:

• The total of all conductors installed at any cross section of the wiring space does not exceed 40 percent of the crosssectional area of that space.
• The total area of all conductors, splices, and taps installed at any cross section of the wiring space does not exceed 75 percent of the cross-sectional area of that space.
• A warning label complying with 110.21(B) is applied to the enclosure that identifies the closest disconnecting means for any feed-through conductors.”

This section implies that wire splices would be allowed inside the switch box as long as the total area of the splices and conductors don’t exceed 75% of the cross-sectional area.

Although it is not ideal, my solution is to use splice connectors (specifically WAGO 221 Series Lever Nuts) to splice together 14 AWG wires from the load terminals of the switch box to the 16 AWG wires that power the equipment inside the switch box. I have included sample pictures for reference.

I have checked with the switch box manufacturer that if the splice connector was UL listed (it is) and the splice meets NEC standards, this solution meets their installation requirements.

According to the pictures (assume <75% cross section is used), would this still be in NEC compliance?

 

[infinity]

Splices are permitted in disconnects.

 

[BoilerBB]

Splices are permitted in disconnects.

Thanks for replying Rob. I have been looking through other posts in this forum and others and have a follow-up question:

I work for a custom equipment manufacturer, and this equipment gets shipped around the world. Although it may meet NEC standards, the local code authority may have an issue with the splicing. Up to this point, no one has had issue with how the wiring currently is. Will making this change cause more trouble with AHJ than it is worth?

 

[petersonra]

I would not be concerned about the splices.

I would be more concerned that the #16 wires are not compliant. They would need to be class 1 circuits and I suspect they are not.

 

[jap]

If I came across this disconnect I would be asking,,,

Why are these splices made?
Where is the equipment grounding conductors or ground bar ?
Why are there 2 Grounded and only 1 Grounded conductor?
Where is the protection for the conductors where they enter the disconnect?

JAP>

 

[BoilerBB]

If I came across this disconnect I would be asking,,,

Why are these splices made?
Where is the equipment grounding conductors or ground bar ?
Why are there 2 Grounded and only 1 Grounded conductor?
Where is the protection for the conductors where they enter the disconnect?

JAP>

The pictures aren't of the actual wiring. This example was made to help visualize the wire splices.

There is a separate grounding bar installed. There are normally two neutral and two hot wires. There are also normally bushings at each of the entrances. These 3 items are ok in the current design (not pictured).

My main concern is with the splices. Like you said, will an inspector say, "That looks funny," or will we be able to point to this passage of the NEC to justify the splices?

 

[petersonra]

The pictures aren't of the actual wiring. This example was made to help visualize the wire splices.

There is a separate grounding bar installed. There are normally two neutral and two hot wires. There are also normally bushings at each of the entrances. These 3 items are ok in the current design (not pictured).

My main concern is with the splices. Like you said, will an inspector say, "That looks funny," or will we be able to point to this passage of the NEC to justify the splices?

If the inspector knows his stuff, he will not be worried about splices like this.

if h does not know his stuff, he will be worried about all kinds of things not required by code.

 

[jap]

The pictures aren't of the actual wiring. This example was made to help visualize the wire splices.

There is a separate grounding bar installed. There are normally two neutral and two hot wires. There are also normally bushings at each of the entrances. These 3 items are ok in the current design (not pictured).

My main concern is with the splices. Like you said, will an inspector say, "That looks funny," or will we be able to point to this passage of the NEC to justify the splices?

The inspector will probably say "That looks funny" then you will be able to bring up the minimum wire sizing of the lugs in the disconnect and then he'll probably say,,,"wow",,,"good catch", "I probably would have never thought of that".

JAP>

 

[jap]

This still seems odd to me.

If used to disconnect (2) separate 120v circuits, how do you assure the 2 incoming individual 120v circuits coming into the disconnect will be fed from 2 different phases as to not overload the neutral jumper from the leverlock splice to the neutral bar?

Also, there will more than likely be 2 small feeder neutrals coming into this disconnect from the panel feeding it landing on a common neutral bar.

Wouldn't this be considered a paralleled Neutral Conductor to the disconnect?

I don't think the Neutral conductors should land on the Neutral Bar in the disconnect.

I feel the incoming and outgoing neutrals should be spliced together separately per their phase.

Or am I reading too much into this?

JAP>

 

[LarryFine]

I see no reason why not.

 

[jap]

The feeder breakers for the 2 individual 120v circuits in the panel feeding the disconnect would require handle ties because you have landed those individual branch circuit neutrals on a common bar in the disconnect.

JAP>

 

[jap]

I may be all wet on this,,, just seems odd that all the branch neutrals are coming together at the disconnect.


JAP>

 

[suemarkp]

Depending on what this is and how rugged it needs to be, you could just crimp on a barrel splice to each conductor putting 14ga out the other end of the barrel. This would be a more solid splice than a removable one such as a Wago or wire nut.

 

[BoilerBB]

The feeder breakers for the 2 individual 120v circuits in the panel feeding the disconnect would require handle ties because you have landed those individual branch circuit neutrals on a common bar in the disconnect.

JAP>

I'm not as experienced with the NEC as the rest of you, so I don't really follow what you are saying.

If this helps give context- Although the switch box accepts 2 phases, only 1 is used in normal 120 VAC use. A 6 Amp fuse is used in the right side of the disconnect. To me, as long as all the wiring in the equipment is rated for at least 6 amps, it should be ok. And if the hot line wire is the same gauge as the neutral line wire, it shouldn't be overloaded.

 

[BoilerBB]

Depending on what this is and how rugged it needs to be, you could just crimp on a barrel splice to each conductor putting 14ga out the other end of the barrel. This would be a more solid splice than a removable one such as a Wago or wire nut.

A barrel splice could work in some cases, but the switch box terminals are also only rated to receive a single wire. In cases where multiple load wires are present, a Wago or wire nut would be needed.