Junction enclosures are becoming more common with growth. When designing a system for growth engineers must look at future expansion. With expansion, an adequately sized transformer must be considered to handle future loads. In the beginning, the transformer must be physically capable (on the secondary side) to tap to various points in the plant. But as future loads are added and the plant expands in physical size, so too must the transformer taps.
Gilbert Electrical has the solution with it’s secondary tap junction enclosure. Junction enclosures gives the user the ability to increase transformer taps without direct alteration of the transformer. By sizing the junction enclosure for the full load current rating of the transformer, a customer may connect the incoming cables from the transformer to the phase buses located inside the junction enclosure. Doing this allows you the room for multiple outgoing taps to various loads.
Junction enclosures are a convenient way to allow for future system expansion.
Built from rugged 11 gauge steel and rated NEMA 3R equivalent, this unit will grow with the system and last just as long.
NEMA 3R – Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt, rain, sleet, and snow; and that will be undamaged by the external formation of ice on the enclosure.
Junction Enclosure come in a variety of sizes. To aid in a quick response for a quotation, please refer to our Part Number Derivation guide to derive a part number. If given a part number, responses to quotations can be immediate. If there is a particular size you desire that is not listed or you would like to customize your order, responses to your request will be within 24 hrs.
As shown below, a junction enclosure connects to the secondary side of the transformer. Since a transformer may have only a limited number of secondary taps, a junction enclosure can be supplied with virtually unlimited taps. This gives the user the ability to plan for growth without the worry of altering the transformer or even perhaps ordering a new one.
Junction enclosures are supplied with a choice of physical size, voltage rating, max amp rating, system type, type of bus and so on. Depending on the need of the system, Gilbert will have no problem finding the right one for you.
Specifications for Bus Enclosures
1.0 Scope:
This specification covers the design and construction of factory assembled pad mounted bus enclosures. Typically, the units are 600-volt class. However, higher voltage units are available.
2.0 Enclosure Construction:
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2.1 The enclosure shall meet IEEE Std. C57.12.28 integrity and paint specification and shall be tamper resistant and weather resistant.
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2.2 The enclosure will be constructed of 11-gauge pickled & oiled steel of bolted construction.
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2.3 The enclosure design will include welded spreader frames at top and bottom.
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2.4 The roofs shall be crowned to shed water.
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2.5 Two doors will be provided as standard. Side panels may be substituted for doors when requested.
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2.6 The doors will have a true three point latching mechanism.
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2.7 Door hinges to be a minimum of 0.375” dia. Stainless steel.
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2.8 All door to be a minimum of 40 inches square. Larger sizes are available.
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2.9 A recessed penta-head bolt may be provided on all doors when specified.
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2.10 Door handles to be capable of accepting a padlock.
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2.11 The door shall be furnished with a door catch that will hold the door 100 degrees open.
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2.12 Standard Voltage and Caution signs will be applied. Optional signs available. Nameplate with Model number, Continuous amps, voltage, BIL, Serial number and date of manufacture will be applied.
3.0 Venting:
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3.1 Enclosure to have adequate venting to reduce condensation within the housing.
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3.2 The vent openings to be covered on the inside with 16 gauge perforated aluminum screen.
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3.3 All vents will be tamper resistant.
4.0 Painting:
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4.1 The enclosure is thoroughly scraped, sanded cleaned and phosphatized before primer coat is applied.
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4.2 A red oxide primer is applied.
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4.3 The topcoat will be silicone enamel, color green, Munsell #7GY3.2/1.5. The paint thickness will be 3.0 Mils after drying. Painted with DuPont Powder Coat paint
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4.4 The paint will meet ANSI standard C57.12.28.1988
5.0 Bus and Mountings:
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5.1 The bus shall be bare copper; aluminum bus can be supplied as an alternate. All burrs and sharp corners will be removed before installation.
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5.2 The bus will be three phases with a neutral and/or ground bus. The neutral bus can be full or half rated. Also the neutral bus can be grounded if the system is three-phase, four wire multi-grounded. As an alternate a neutral and a separate ground bus can be furnished.
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5.3 Standard busing hole arrangement will be twenty-two locations. The hole size will be 9/16” with the following bus sizes based on ampacity requirements:
| Amps @ 50° C |
BUS SIZE |
| 600 |
¼” X 2” * |
| 1200 |
¼” X 3” * |
| 1500 |
¼” X 4” |
| 2000 |
½” X 4” |
| 2500 |
½” X 5” |
| 3000 |
½” X 6” |
| 4000 |
½” X 8” |
| * Bus of this size will have one 9/16” hole. The larger bus will have two 9/16” holes per lug connections 1.75” between centerline of these holes. Lugs to be furnished by others. |
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| Higher rated bus is available. |
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5.4 The insulators will be fully rated BIL per voltage requirements. Bus will be adequately braced for the available short circuit current.
6.0 Packaging:
6.1 Each enclosure will be bolted to a wooden pallet. The equipment will be wrapped with corrugated cardboard and then shrink wrapped with plastic to provide protection during shipment.