Okay, let's break down this NEC interpretation question and the contractor's pushback. You're essentially asking: Does the NEC require low-point drains (LPDs) in all outdoor, above-ground conduit runs, even for control/instrument wiring in a C1/D2 location?

Here's a balanced approach

Arguments FOR Requiring/Justifying LPDs (Even if not explicitly mandated by NEC for all situations):
Your Reasoning is Valid

You're concerned about condensation and its potential damage to both the conductors/cables and the conduit itself (corrosion). This is a very reasonable and proactive approach, especially in New England's climate. This is your company's standard/design and should be followed if you can not find NEC contradicting it.

NEC Encouragement of Draining

While the contractor is correct that 225.24 and 230.53 specifically address outdoor feeders and service conductors, the intent behind those articles is to prevent water accumulation that could cause damage. The NEC commentary often hints at broader application of principles.

Article 300.6 Protection Against Corrosion

This article addresses the protection of electrical equipment, raceways, and enclosures from corrosion. While it doesn't explicitly mention draining, the accumulation of water contributes to corrosion. Using LPDs helps mitigate this.

C1/D2 Considerations (Hazardous Locations)

The C1/D2 (Class 1, Division 2) designation adds another layer of complexity. While not directly related to draining, proper wiring methods are critical in these areas to prevent ignition sources. Water accumulation can degrade insulation and potentially create faults.

Industry Best Practices

Installing LPDs in outdoor conduit, especially in areas with significant temperature fluctuations and/or humid climates, is generally considered a good industry practice. This is especially true in industrial settings and with instrumentation/control wiring where reliability is paramount.

Preventative Maintenance

LPDs can be viewed as a preventative maintenance measure. They allow for periodic draining of accumulated moisture, extending the lifespan of the wiring and conduit system.

Local Amendments/AHJ Interpretation

Your local Authority Having Jurisdiction (AHJ) may have interpretations or amendments to the NEC that require or strongly recommend draining in outdoor conduit systems. Check with your local inspection authority.

Contractor's Arguments (and Rebuttals)



NEC Doesn't Explicitly Require for Control/Instrument Wiring

They are technically correct that 225.24 and 230.53 are specifically worded for feeders and services.

Rebuttal

The principle behind those articles is to prevent water accumulation and its associated damage. Article 300.6 is applicable. The C1/D2 location adds an additional safety consideration. And, most importantly, this is your company's standard.

Cost

This is often the unspoken (or spoken) reason for resistance. Installing LPDs adds material and labor costs.

Rebuttal

This should have been factored into the original bid based on your specifications. If not, you may need to negotiate, but emphasize the long-term benefits of the LPDs.

How to Proceed


Review Your Project Specifications

The most important factor. If your project specifications explicitly require LPDs in outdoor conduit runs (regardless of wiring type), the contractor is obligated to follow them. This is where you have the strongest leverage.2.

Reference Your Company Standards

If your company has a documented standard for installing LPDs in outdoor conduit, present this to the contractor.3.

Consult with Your Engineering Team

If there's any ambiguity in the specifications or standards, consult with your electrical engineers or designers. They can provide a written clarification or justification for the LPDs.4.

Engage the AHJ (If Necessary)

As a last resort, if the contractor remains resistant, you can contact your local AHJ for their interpretation of the NEC in this specific situation.5.

Document Everything

Keep a clear record of all communications, specifications, and interpretations. This will be helpful if disputes arise later.6.

Emphasize the Why

Explain to the contractor the reasons behind your requirement for LPDs (climate, C1/D2 location, corrosion prevention, long-term reliability). Often, understanding the rationale can reduce resistance.7.

Compromise (Potentially)

If absolutely necessary and if the risk assessment allows, you might consider a compromise, but only if you're confident that the alternative solution will still provide adequate protection. For example, you could agree to LPDs only in specific locations where water accumulation is most likely. This is not recommended unless you have significant engineering input.

In Conclusion:

While the NEC may not explicitly mandate LPDs in all* outdoor conduit runs, your reasons for requiring them are valid, especially given the New England climate, the C1/D2 location, and your company's standards. Stand your ground, back up your position with documentation and engineering justification, and communicate clearly with the contractor. You are trying to do the job the safest and most reliable way as possible.I would side with your companies standard as being the best practice. Flag for review