Delfield Prep Table Error Code uHi: Line Voltage Too High
UHi on a Delfield NP prep table means the control sees a supply voltage above 140 volts. The manual gives no operator action for it. Call a technician to check the receptacle and supply.
High: a supply voltage above the control's limit can damage the compressor and electronics.
- Code
- UHi
- Maker
- Delfield
- Equipment
- Prep tables
- Applies to
- 4400/4500 Series NP refrigerated prep tables with R290 temperature control (4424NP-4472NP, D4424NP-D4472NP, ST4424NP-ST4472NP and variants)
What does Delfield error code UHi mean?
The R290 control for a Delfield NP prep table monitors the voltage of the electrical line that feeds it. If the line voltage goes above 140 volts, it shows uHi. The manual describes it as line voltage too high and lists one cause, a supply voltage above 140 V. No operator action is given in the manual. Its alarm timing follows the same pattern as the other alarms: the alarm sounds for about 10 seconds, stays silent for 50 seconds, repeats for 15 cycles and then stays silent, and the code stays on the display until the condition clears. Because the cause lies in the electrical supply and not in the table, the usual fix is on the building side or in how the table is connected.
Affected models and control systems
The manual covers the 4400 and 4500 Series NP refrigerated prep tables with the R290 temperature control, including the 4424NP to 4472NP, D4424NP to D4472NP and ST4424NP to ST4472NP sizes and their variants.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- UHi on the display
- Alarm sounding for about 10 seconds each minute
- Lights or other equipment on the same circuit behaving oddly
- Compressor starting with a hum or not at all
Possible causes
Listed in Delfield's documentation
- Supply voltage above 140 V
Other likely causes — what usually sits behind error code UHi on this control. A technician confirms which one it is before any part is replaced.
- Table plugged into a receptacle wired for a higher voltage than the table expects
- Loose neutral on the branch circuit raising the voltage on one leg
- Large equipment on the same circuit switching off and lifting the line voltage
Safe checks before calling for service
- Check that the plug is in the receptacle intended for this table, not one that belongs to other equipment.
- Ask whether any electrical work was done recently in the kitchen.
- Do not use adapters or extension cords on the table's plug.
- Leave the table off if the alarm repeats, so the compressor is not run on an unsafe supply.
- For the service call, note when uHi first appeared and any recent power work.
How a technician diagnoses error code UHi
- Read uHi and measure the receptacle voltage with a meter, with the table running and off.
- Check the circuit's voltage rating against the table's nameplate.
- Check the neutral and ground connections on the branch circuit.
- Observe whether other loads on the same circuit change the reading.
- Correct the supply and confirm the control reads normal voltage.
- Measuring live receptacle voltage and tracing the branch circuit is electrician-level work on 115 V wiring.
- A neutral or supply problem can damage the compressor or control if the table keeps running.
- The table's nameplate and the circuit rating have to be matched by someone who can change the wiring.
How error code UHi differs from similar codes
UHi is the high-voltage counterpart of uLo. ULo triggers below 96 volts, and uHi above 140 volts.
Technical reference
- Document
- Prep Tables & Compact Refrigerators, 4400 & 4500 Series: Specifications, Installation, Operation & Maintenance Manual
- Edition
- Part Number 9295093A, 11/25 (page footers 10/25)
- Models / control
- 4400/4500 Series NP refrigerated prep tables with R290 temperature control (4424NP-4472NP, D4424NP-D4472NP, ST4424NP-ST4472NP and variants)
- Section
- Section 3 Operation, control table p. 24
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Delfield prep table error codes
Does uHi mean the table is broken?
The manual lists only a supply voltage above 140 V as the cause, so the problem is usually the power feeding it.
Can I reset it?
The manual gives no reset. The code stays on the display until the condition clears.
Is it the same as uLo?
No. UHi is a voltage that is too high and uLo is a voltage that is too low.
Need help with Delfield error code UHi?
A technician confirms the cause on site and gives you the price in writing before any work starts.