Milbank 320A 1-Phase Ringless ...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$1,155.39
Milbank 4 Terminal Ringless Large Closing Plate Lever Bypass Utility Grade

Milbank 320A 1-Phase Ringless Meter Socket with Lever Bypass and Large Closing Plate (4)

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Model: U4257-X

In Stock (leaves warehouse same day if ordered before 3pm ET)

$1,155.39
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Milbank 320A 1-Phase Ringless Meter Socket with Lever Bypass and Large Closing Plate

Professional utility-grade metering solution with integrated bypass capability

The Milbank 320A 1-Phase Ringless Meter Socket delivers reliable electrical metering with professional lever bypass functionality and large closing plate design. Constructed with G90 galvanized steel and powder coat finish in a Type 3R enclosure, this utility-grade meter socket provides 320 continuous ampere capacity at 600V AC with glass polyester insulation for dependable service in demanding applications.

Professional Features & Benefits

  • 320 Continuous Ampere Rating: Handles substantial electrical loads with reliable capacity for commercial and industrial metering applications.
  • Lever Bypass Provision: Enables safe meter maintenance and replacement without service interruption through integrated bypass functionality.
  • Type 3R Enclosure Rating: Weather-resistant construction protects internal components from rain, sleet, and ice formation for outdoor installations.
  • G90 Galvanized Steel Construction: Durable material with powder coat finish provides long-lasting corrosion resistance and structural integrity.
  • Large Closing Plate Design: Enhanced hub closing plate configuration ensures secure connections and professional installation appearance.
  • UL Listed Certification: Meets rigorous safety standards for reliable performance and code compliance in utility applications.
  • Glass Polyester Insulation: High-quality insulation material provides excellent electrical isolation and thermal stability.

Technical Specifications

  • Amperage Rating: 320 Continuous Ampere
  • Application: Meter Socket
  • Brand Name: Milbank
  • Bypass Provision: Lever Bypass
  • Departent: Electrical
  • Equipment Ground: Ground Lug
  • Frequency Rating: 60 Hertz
  • Hub Closing Plate: Large Closing Plate
  • Insulation: Glass Polyester
  • Line Side Wire Range: Two 6 AWG - 350 kcmil
  • Load Side Wire Range: Two 6 AWG - 350 kcmil
  • Main Breaker Size: No Main Breaker
  • Number Of Jaws: 4 Terminal
  • Number Of Main Breakers: 0
  • Number Of Meter Positions: 1 Position
  • Number Of Receptacles: 0
  • Phase: 1 Phase
  • Product Family Code: 4T32
  • Product Height: 34.125 IN
  • Product Length: 6.5 IN
  • Product Material: G90 Galvanized Steel with Powder Coat Finish
  • Product Mounting: Surface Mount
  • Product Size: 6.5L x 19W x34.125H
  • Product Type: Ringless Meter Socket
  • Standard: UL Listed;Type 3R
  • Unspsc Number: 39121102
  • Voltage Rating: 600 Volts Alternating Current
  • Width: 19 IN

Professional Applications

  • Commercial Building Metering
  • Industrial Facility Power Distribution
  • Multi-Unit Residential Properties
  • Retail and Office Buildings
  • Municipal and Government Facilities
  • Educational Institution Power Systems
  • Healthcare Facility Electrical Infrastructure

Why Choose Milbank Quality?

Milbank delivers proven reliability through UL Listed certification and Type 3R weather-resistant construction. The G90 galvanized steel with powder coat finish ensures long-term durability, while the professional 4-terminal ringless design provides secure connections for demanding utility applications.

Manufacturer Resources

Product Specs

Amperage Rating:
320 Continuous Ampere
Application:
Meter Socket
Brand Name:
Milbank
Bypass Provision:
Lever Bypass
Equipment Ground:
Ground Lug
Frequency Rating:
60 Hertz
Hub Closing Plate:
Large Closing Plate
Insulation:
Glass Polyester
Line Side Wire Range:
Two 6 AWG - 350 kcmil
Load Side Wire Range:
Two 6 AWG - 350 kcmil
Main Breaker Size:
No Main Breaker
Number Of Jaws:
4 Terminal
Number Of Main Breakers:
0
Number Of Meter Positions:
1 Position
Number Of Receptacles:
0
Phase:
1 Phase
Product Family Code:
4T32
Product Height:
34.125 IN
Product Length:
6.5 IN
Product Size:
6.5L x 19W x34.125H
Product Type:
Ringless Meter Socket
Standards:
UL Listed;Type 3R
Unspsc Number:
39121102
Voltage Rating:
600 Volts Alternating Current
Product Material:
G90 Galvanized Steel with Powder Coat Finish
Product Mounting:
Surface Mount
Amps:
320
Product Width:
19 IN
Department:
Electrical
Product Subgroup:
Metering & Meter Sockets
Insulation Type:
Glass Polyester
Hub Style:
Large Closing Plate
Installation Category:
Surface Mount
Number of Phases:
1
Product Details:
Ringless Meter Socket
Frequency:
60 hertz
Number of Terminations:
4
Product Group:
Power Distribution

Milbank U4257-X – Frequently Asked Questions

1) Will the Milbank U4257-X meter socket work for a 320 amp single-phase residential or commercial service?
Yes. The Milbank U4257-X is rated 320 continuous amperes, 1 phase, 600V AC, 60 Hz, with a single meter position and 4 terminal jaws. That 4-jaw single-phase configuration is the standard for a 320A (400A class) overhead or underground service where the utility meters one position. It has no main breaker, so overcurrent protection has to come from downstream panels or a separate disconnect.
2) What size service conductors will fit the lugs on this 320A Milbank ringless socket?
Both line and load terminals accept two conductors each, 6 AWG through 350 kcmil. That means parallel 350 kcmil per phase coming in and going out, which is what a 320A service typically needs. If your feeder is a single larger conductor than 350 kcmil, it will not land in these lugs.
3) Can this meter socket be installed outdoors on an exterior wall?
Yes. It is a Type 3R enclosure, UL Listed, built from G90 galvanized steel with a powder coat finish, so it is intended for outdoor surface mounting and sheds rain, sleet, and ice. It is a surface mount unit, not flush or semi-flush, so it needs a flat exterior wall or a mounting backboard.
4) What does the lever bypass on this Milbank socket actually do for me on a service call?
The lever bypass lets a lineman or electrician close a bypass across the meter jaws so the meter can be pulled and changed without dropping power to the building. For a property manager with occupied units, that is the difference between a meter swap and an outage notice. Many utilities require lever bypass on 320A class self-contained sockets, so confirm it against your utility's approved equipment list.
5) What is the difference between the Side-Bussed and 2-Connector (6-350 kcmil) versions of the U4257-X?
Two build options are offered. The base U4257-X is side-bussed. The U4257-X-2/K2 is furnished in a 2-connector configuration accepting 6 to 350 kcmil, which is the choice when you are landing two parallel conductors per phase on each terminal. Pick based on how your service conductors arrive and what your utility accepts.
6) Can I use this Milbank socket on a 3-phase service?
No. It is a 1-phase, 4-terminal socket with four terminations. A 3-phase service needs a 7-jaw socket. Using this on three phase is not a configuration it supports.
7) Does this meter socket include a main breaker or any receptacles for a meter-main application?
No. There is no main breaker and no receptacles, and the meter position count is one. It is a straight meter socket, not a meter-main combination. If you need metering plus service disconnect in one enclosure, specify a meter-main instead and plan a separate disconnect alongside this socket if you stay with it.
8) Does a ringless meter socket like this need a separate sealing ring?
No. A ringless socket uses a hinged or lift-off cover that is secured and sealed by the utility, with no separate locking ring around the meter. If your utility specifies ring-type sockets, this 4-terminal ringless unit is the wrong style and you need a ring-type socket instead.
9) Is there a hub for conduit entry, or do I have to cut my own?
The unit ships with a large closing plate rather than a factory hub. The plate covers the top opening, and you install the hub or fitting sized for your service raceway in that opening. Order the hub separately to match your conduit size.
10) Is there a ground lug in this meter socket, or do I need to add one?
A ground lug is provided for the equipment grounding connection, so you do not need to add a separate grounding kit for that termination. Bonding and neutral arrangement still follow your utility's requirements for a service-entrance location.
11) We are standardizing meter sockets across a multi-building site. What identifiers should go on the spec?
Spec it as Milbank, family code 4T32, model U4257-X for the side-bussed build or U4257-X-2/K2 for the 2-connector version. Supporting line items for a submittal: 320 continuous amp, 1 phase, 600V AC, 4 terminal, ringless, lever bypass, Type 3R, UL Listed, surface mount, UNSPSC 39121102.
12) What insulating material supports the meter jaws, and will it hold up in a hot or humid location?
The jaw assembly is insulated with glass polyester, which holds dielectric strength and dimensional stability at the temperatures a 320A socket sees under load. Paired with the G90 galvanized steel and powder coat shell and the Type 3R rating, it is built for outdoor service entrance duty.
How fast can I get the Milbank U4257-X delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Milbank U4257-X come with a warranty?
Absolutely. The Milbank U4257-X is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Milbank U4257-X?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
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