Yes, I'm familiar with ConEd's (Consolidated Edison) typical service offerings in lower New York (specifically NYC). Here's the breakdown of what to expect and what might be happening

ConEd Service Voltage Standard:
Generally, ConEd provides 480V/277V, 3-phase, 4-wire service. This is their standard for commercial and industrial customers who require higher power levels. The 480V is phase-to-phase voltage, and 277V is phase-to-neutral.

Why You Might Be Seeing 460V



Voltage Drop

The most common reason you're reading 460V instead of 480V is voltage drop in the distribution system. Voltage drop occurs as electricity flows through the wires and components from the transformer to your client's equipment. Distance, wire size, load, and power factor all contribute to voltage drop. The transformer may output 480V at the transformer, but by the time it reaches the equipment, it has dropped.

Transformer Taps

Transformers often have taps that allow you to adjust the output voltage slightly. These taps are typically set during installation and shouldn't be adjusted without careful consideration and expertise. It's possible the transformer tap setting is not optimal.

ConEd System Voltage Issues

While less common, the problem could also be on the ConEd side. System load variations, especially during peak demand times, can sometimes cause temporary voltage dips in the grid.

Meter Accuracy

While unlikely, it's worth verifying the accuracy of your metering equipment.

Troubleshooting Steps


Confirm Transformer Output

Verify the actual output voltage at the secondary terminals of the transformer itself. This is your starting point. If it's truly 480V at the transformer, then the problem is voltage drop. If it's lower than 480V at the transformer, then investigate the following:

Transformer Taps

Check the tap settings on the transformer. There should be a diagram on the transformer indicating the output voltage for each tap.

Transformer Condition

Have the transformer inspected by a qualified electrician or transformer specialist. There could be internal problems causing a voltage drop.

ConEd Service Voltage

Contact ConEd and inquire about the service voltage they are providing to the building. They may be able to confirm the expected voltage level at the service entrance. Provide them with your voltage logging data. They might have records of known issues in the area.2.

Analyze Voltage Drop

If the transformer is outputting 480V, then focus on voltage drop.

Measure Voltage at Multiple Points

Measure the voltage at various points along the distribution path, from the transformer to the HVAC equipment. This will help pinpoint where the voltage drop is occurring.

Check Wire Sizes and Runs

Verify that the wire sizes and lengths are adequate for the load and distance. Use voltage drop calculators to determine if the wiring is properly sized.

Examine Connections

Inspect all electrical connections (terminals, lugs, splices, etc.) for looseness, corrosion, or damage. Poor connections are a common source of voltage drop.

Load Analysis

Analyze the load on the circuit. Are there any large or intermittent loads that could be causing excessive voltage dips?3.

Power Factor Correction

A low power factor can exacerbate voltage drop. Consider installing power factor correction capacitors to improve the power factor and reduce the current flow in the system.4.

Dedicated Feeders

If possible, consider running dedicated feeders directly from the transformer to the HVAC equipment. This will minimize voltage drop and improve voltage stability.5.

Voltage Regulators

In extreme cases, you might consider installing voltage regulators to maintain a stable voltage supply to the HVAC equipment. However, this is a more costly solution.

Reviewing Your Data

Yes, I would be happy to review your voltage logging data. Sharing the data (or a summary) will help me provide more specific recommendations. I would be interested to know the following:

Sampling Rate

How often was the voltage measured (e.g., every minute, every hour)?

Duration

How long was the logging period?

Minimum Voltage

What was the lowest voltage recorded during the logging period?

Maximum Voltage

What was the highest voltage recorded?

Average Voltage

What was the average voltage?

Standard Deviation

What was the standard deviation of the voltage? This will give you an idea of how much the voltage fluctuates.

Time of Day

Note when the dips occur. Do they occur during the hottest time of the day when usage is at its peak?

Location of Measurement

Specifically, where was the voltage measured? At the main panel, at the HVAC equipment, at the transformer?

HVAC Equipment Sensitivity

Some HVAC equipment is more sensitive to voltage fluctuations than others. Check the manufacturer's specifications for the acceptable voltage range of the equipment.

Important Considerations



Licensed Electrician

All electrical work should be performed by a qualified and licensed electrician familiar with ConEd requirements.

ConEd Coordination

Communicate with ConEd about your findings and proposed solutions. They may be able to provide additional insights or assistance.

In summary: While ConEd should be providing 480V/277V, voltage drop is extremely common, especially in dense urban environments. A thorough investigation of the system, starting at the transformer and working towards the HVAC equipment, is necessary to identify and address the problem. Your data is invaluable in this process. Flag for review