The contractor's explanation is highly suspect and likely incorrect. There is generally no NEC code that prevents an SPD (Surge Protective Device) from being connected directly to the main lugs in a panelboard or disconnect. In fact, direct connection to the lugs is often the preferred and recommended method.Here's a breakdown of why the contractor is likely wrong, and what the relevant NEC considerations are: NEC Preference for Short Lead Lengths

SPDs work by diverting surge current to ground. To be effective, the conductors connecting the SPD to the electrical system should be as short as possible. Longer conductors increase inductance, which impedes the fast-acting response of the SPD and reduces its effectiveness. Connecting directly to the main lugs is usually the shortest path.

NEC 285.25 (2020 NEC) This section specifically addresses SPD connection requirements. It requires SPDs to be installed in accordance with the manufacturer's instructions, which usually specify the minimum wire size and may even suggest direct connection to lugs for optimal performance. (A) Location. SPDs shall be located after the service disconnecting means. (B) Connection to the Circuit. SPDs shall be connected to the load side of an overcurrent protective device. The connection shall be as short as practicable. Why Direct Connection is Better (Generally)



Lower Impedance

Direct connection to the lugs minimizes the impedance (resistance to AC current flow) in the SPD's connection path. Lower impedance allows the SPD to respond faster and more effectively to surges.

Better Surge Handling

Direct connection typically allows the SPD to handle higher surge currents.

Reduced Risk of Induced Voltages

Longer conductors (like those used with Polaris taps) can pick up induced voltages from nearby conductors during a surge event, which can interfere with the SPD's operation.

Why the Polaris Tap Explanation is Likely False



Polaris Taps Add Impedance

Polaris taps introduce additional connection points, increasing the overall impedance in the SPD's connection path.

Unnecessary Complexity

Adding Polaris taps adds unnecessary complexity and potential points of failure.

Potential for Improper Installation

Polaris taps must be properly sized and torqued, introducing another potential for installation error.

Possible (But Unlikely) Exceptions/Reasons the Contractor Might Be Using Polaris Taps (and why they're probably wrong)



Lack of Space in the Panel

In very rare cases, there might be so little physical space in the panel that directly connecting the SPD to the lugs is extremely difficult. However, this is a design flaw of the panel or incorrect SPD selection, not an NEC violation. A properly sized panel should have adequate space.

Lug Size Compatibility

The lugs on the SPD might not be compatible with the main conductors in the panel. However, this can usually be addressed by using appropriately sized reducing connectors or lugs.

Manufacturer's Instructions (Very Unlikely)

It's possible that the specific SPD manufacturer's instructions require the use of a specific type of tap, but this is extremely rare and unlikely. If so, the contractor needs to provide those instructions.

Panel Manufacturer Restrictions (Very Unlikely)

Some panel manufacturers might have restrictions regarding adding components to the main lugs. Again, unlikely, but if so, the contractor needs to provide documentation.

What to Do


Demand Justification

Ask the contractor to provide the specific NEC code section or the manufacturer's instructions that prohibit direct connection to the main lugs. They will likely be unable to do so.2.

Request RFI with the engineer of record

The contractor is putting forward a claim that they are following code, and the inspector has the right to ask the contractor to provide documentation.3.

Review SPD Manufacturer's Instructions

Carefully review the SPD manufacturer's installation instructions. They will almost certainly recommend or allow direct connection to the lugs if possible.4.

Consult with an Electrical Engineer

If there is still a disagreement or uncertainty, consult with a qualified electrical engineer to review the installation and ensure it meets code and best practices.5.

Reject the Installation

If the contractor cannot provide a valid justification for using the Polaris taps, reject the installation and require them to connect the SPD directly to the lugs according to the manufacturer's instructions and NEC requirements.

In summary, the contractor's explanation is highly questionable. Direct connection of SPDs to the main lugs is generally the preferred and code-compliant method. The use of Polaris taps is likely unnecessary, adds impedance, and may reduce the effectiveness of the SPD. Flag for review