Routing Through Bottom of Unit — If wiring is brought in through bottom of unit, use field-supplied watertight conduit to run power wiring from basepan out through bottom 31/2-in. hole to the disconnect box and back into unit to the main con- trol box.

Use strain relief going into control box through 21/2-in. di- ameter hole provided. After wires are in unit control box, con- nect to power terminal block (see Power Wiring section on page 33).

Low-voltage wiring must be run in watertight conduit from the basepan to control box and through 7/8-in. diameter hole provided in bottom of unit control box. Field-supplied strain re- lief must be used going into the box. After wiring is in control box, make connections to proper terminals on terminal blocks (see Field Control Wiring section on this page).

Install conduit connector in unit basepan as shown in Fig. 5-16. Route power and ground lines through connector to terminal connections in unit control box as shown on unit wir- ing diagram and Fig. 28.

Routing Through Side of Unit — Route power wiring in field-supplied watertight conduit into unit through 21/2-in. or 3-in. hole. See Fig. 28.

Use field-supplied strain relief going into control box through 21/2-in. or 3-in. diameter hole provided. After wires are in unit control box, connect to power terminal block (see Pow- er Wiring section on page 33).

Bring low-voltage control wiring through factory-drilled 7/8-in. diameter hole in condenser side post. Use strain relief going into 7/8-in. diameter hole in bottom of unit control box.

After wiring is in control box, make connection to proper terminals on terminal blocks (see Field Control Wiring section below).

IMPORTANT: The VAV (variable air volume) units use variable frequency drives, which generate, use and can radiate radio frequency energy. If units are not installed and used in accordance with these instructions, they may cause radio interference. They have been tested and found to comply with limits of a Class A computing device as defined by FCC (Federal Communications Commission) regulations, Subpart J of Part 15, which are designed to provide reasonable protection against such interference when operated in a commercial environment.

The unit must be electrically grounded in accordance with local codes and NEC ANSI/NFPA 70 (National Fire Pro- tection Association).

Affix crankcase heater sticker (located in the installers pack- et) to unit disconnect switch.

Voltage to compressor terminals during compressor opera- tion must be within the voltage range indicated on the unit nameplate. On 3-phase units, phases must be balanced within 2%.

Use the formula in Tables 7 and 8 to determine the percent- age of voltage imbalance.

IMPORTANT: If the supply voltage phase imbalance is more than 2%, contact your local electric utility company immediately.

Unit failure as a result of operation on improper line voltage or excessive phase imbalance constitutes abuse and may cause damage to electrical components.

On 208/230-v units, transformer no. 1 is wired for 230-v. If 208/230-v unit is to be run with 208-v power supply, the trans- former must be rewired as follows:

1.Remove cap from red (208 v) wire.

2.Remove cap from spliced orange (230 v) wire. Discon- nect orange wire from black unit power wire.

3.Cap orange wire.

4.Splice red wire and black unit power wire. Cap wires.

IMPORTANT: BE CERTAIN UNUSED WIRES ARE CAPPED. Failure to do so may damage the transformers.

FIELD CONTROL WIRING — Install either a Carrier- approved thermostat or a CCN (Carrier Comfort Network) compatible temperature sensor. Thermostats are used on CV (constant volume) units only. Control box diagrams are shown in Fig. 29-31.

LEGEND

GND — Ground

NEC — National Electrical Code

TB — Terminal Block

Fig. 28 — Field Power Wiring Connections

43

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Carrier 48AY020-060, 48EW, 48EY024-068, 48AW, 48EK, 48AK, 48AJ, 48EJ specifications Field Power Wiring Connections, GND Ground
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48EJ, 48AJ, 48AK, 48EK, 48AY020-060 specifications

The Carrier 48EJ, 48AW, 48EK, 48AJ, and 48EY024-068 are cutting-edge rooftop air conditioning units designed for commercial applications. These models are renowned for their reliability, energy efficiency, and innovative technologies aimed at providing optimal indoor comfort.

One of the standout features of these units is their advanced cooling and heating capabilities. They employ a multi-stage compressor system that allows for precise temperature control, accommodating various load requirements. This flexibility is particularly beneficial in commercial settings where the cooling load can fluctuate throughout the day.

Energy efficiency is paramount in today’s environmental landscape, and Carrier has ensured that these models meet stringent efficiency standards. They incorporate high-efficiency scroll compressors, which significantly reduce energy consumption while delivering powerful performance. The units are also equipped with variable speed fans that adjust airflow based on demand, further optimizing energy use.

In terms of construction, these rooftop units feature a robust design that enhances durability and longevity. The cabinet is constructed to withstand harsh weather conditions, ensuring reliable performance year-round. Additionally, the units are equipped with corrosion-resistant coatings, particularly useful in coastal environments where salt exposure can be a concern.

The Carrier 48EJ, 48AW, 48EK, 48AJ, and 48EY models utilize advanced controls and connectivity features, allowing for easy integration into building management systems. This connectivity enables remote monitoring and control, facilitating quick response to changing conditions and simplifying maintenance tasks.

Noise reduction is another key characteristic of these models. They are designed with sound-absorbing insulation and low-noise fan blades to ensure quiet operation, making them suitable for noise-sensitive environments such as schools and hospitals.

These units are also available with various options for air filtration and dehumidification. The use of high-efficiency air filters enhances indoor air quality by trapping dust, pollen, and other airborne particles. Enhanced dehumidification capabilities ensure that spaces remain comfortable even in humid conditions.

In conclusion, the Carrier 48EJ, 48AW, 48EK, 48AJ, and 48EY024-068 rooftop units are engineered to offer exceptional performance, energy efficiency, and durability. With their advanced technologies and user-friendly features, they stand out as reliable solutions for meeting diverse commercial cooling and heating needs, making them a popular choice for many businesses.
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