Okay, this is a common situation, and it's important to get it right. Here's a breakdown of the code considerations and a recommended approach, keeping in mind I am an AI and not a licensed electrician, so consult with one for your install.

Understanding the Key Issues Bundling

The National Electrical Code (NEC) addresses bundling because it affects the ampacity (current-carrying capacity) of conductors. When conductors are bundled together, they generate more heat, and that heat is harder to dissipate. The NEC requires ampacity adjustments (derating) when cables are bundled to prevent overheating and potential fire hazards.

Support

NM cable needs to be supported to prevent strain on connections and protect the cable from physical damage.

Physical Protection

Cables should be protected from physical damage, especially in areas where they might be exposed or easily contacted.

Code Sections to Consider (2023 NEC, consult your local jurisdiction's adopted version)



NEC 334.30 (Securing and Supporting)

This section is CRITICAL. NM cable must be secured to the building structure by staples, cable ties, straps, or similar fittings designed and installed so as not to damage the cable. It requires support every 4 1/2 feet and within 12 inches of boxes or enclosures.

NEC 310.15(B)(3)(a) (Adjustment Factors - More Than Three Current-Carrying Conductors in a Raceway or Cable or Earth [Direct Burial])

This section is about ampacity derating. It states that when more than three current-carrying conductors are bundled in a raceway, cable, or directly buried, the ampacity of the conductors must be reduced (derated) according to a table. The degree of derating depends on the number of current-carrying conductors. Neutral conductors that carry only the unbalanced current from other conductors of the same circuit are not considered current carrying conductors
Analysis of Your Situation and Recommendations1. Are you Bundling? Technically, yes, tying the cables together with cable ties every 3 feet would constitute bundling as the NEC defines it.2. Ampacity Derating is Likely Required

With 15 mixed-gauge NM cables in close proximity, you are almost certainly exceeding the three current-carrying conductor limit that triggers ampacity derating. This is the biggest concern.3.

Support Requirements

Laying the cables on the 2x4s without any securing doesn't meet the NEC's support requirements.

Here's what you should do to be compliant and safe (again, consult a licensed electrician for specific advice)



Calculate Current-Carrying Conductors

For each cable, determine how many current-carrying conductors it has. Generally: 14/2, 12/2, 10/2: 2 current-carrying conductors (hot and neutral). The ground wire isn't counted for derating. 14/3, 12/3, 10/3: 3 current-carrying conductors (hot, hot, neutral). The ground wire isn't counted for derating. Add up the total number of current-carrying conductors.

Determine Derating Factor

Look at NEC Table 310.15(C)(1) (or the equivalent in your local code) to find the ampacity adjustment factor based on the total number of current-carrying conductors you calculated.

Calculate Adjusted Ampacity

For each conductor size (14 AWG, 12 AWG, etc.), take the cable ampacity from NEC Table 310.16 and multiply it by the adjustment factor you found.

Verify Circuit Breaker/Fuse Protection

Make sure that the circuit breakers or fuses protecting each circuit are rated no higher than the adjusted ampacity you calculated. If the adjusted ampacity is lower than the existing breaker/fuse rating, you'll need to reduce the breaker/fuse size.

Properly Support the Cables

Use cable ties, straps, or staples specifically designed for NM cable. Don't use staples that will damage the cable sheathing. Support the cables every 4 1/2 feet and within 12 inches of any boxes or enclosures. Instead of bundling tightly, consider using broader straps or cable trays that allow some space between the cables for better heat dissipation. If this method is used consult with local jurisdiction for approval.

Consider a Different Wiring Method

Depending on the situation, it might be easier and more code-compliant to run the circuits in conduit (EMT or PVC) rather than using NM cable. This would require a different set of calculations and wiring practices. However, it provides more physical protection and simplifies ampacity calculations.

Document Everything

Keep a record of your calculations, the ampacity adjustments you made, and the breaker/fuse ratings you used. This will be helpful for future reference and for any inspections.

Important Considerations and Recommendations Consult a Licensed Electrician

I strongly recommend consulting with a licensed electrician to evaluate your specific situation and ensure that your wiring is safe and code-compliant. They can perform the necessary calculations, make recommendations for the best wiring method, and ensure that everything is properly installed.

Safety First

Always disconnect power to any circuits you are working on before starting any electrical work.

Overkill is Okay (Within Reason)

When in doubt, it's better to over-engineer the wiring to ensure it's safe and reliable. For example, you could consider using larger gauge conductors than strictly required to reduce voltage drop and improve performance.

Example (Simplified)

Let's say you have: Five 14/2 NM cables (5 x 2 = 10 current-carrying conductors) Five 12/2 NM cables (5 x 2 = 10 current-carrying conductors) Five 14/3 NM cables (5 x 3 = 15 current-carrying conductors) Total = 35 Current carrying conductorsAccording to NEC Table 310.15(C)(1), for 31-40 current-carrying conductors, the adjustment factor is 50%. 14 AWG Cable: Ampacity is 15A 0.5 = 7.5A. You would need to protect this with a 7.5amp breaker or next lowest standard size breaker. 12 AWG Cable: Ampacity is 20A 0.5 = 10A. You would need to protect this with a 10amp breaker.

In summary: You need to address the bundling and support issues. The most important aspect is the ampacity derating because of the large number of cables running together. Contact a licensed electrician to perform these calculations and ensure your wiring is safe and code-compliant. Flag for review