EUM is assignee of Electric Installation Section # 1 established in Kharkov in 1944 to restore energy plants of Eastern Ukraine destroyed in World War Two.
In 1945 Kharkov Installation Section # 1 became part of Donbass Electric Installation Trust created by USSR Ministry of Power Plant Construction.
This trust in 1959 was renamed Kharkov Electric Network Construction Trust, and Kharkov Installation Section # 1 became Mobile Mechanized Installation Column # 26.
In 1962 Kharkov Electric Network Construction Trust was renamed Southern Electric Installation Trust (Elektroyuzhmontazh in Russian) under the auspices of USSR Ministry of Power and Electrification, whereas Column # 26 became Kharkov Installation Authority # 1 of Elektroyuzhmontazh Trust.
In March 1994 Kharkov Installation Authority # 1 was renamed Kharkov Assembly & Production Enterprise Elektroyuzhmontazh Company (EUM).
After re-registration it implemented a number of large projects, including installation of 110/35/10 kV substation with gas-insulated switches at Shebelinka, Ukraine; replacement of 220 MVA 330/220 kV autotransformer at Simferopol substation, Crimea; full scope of installation works in update of 300 MW generating unit # 8 at Zmiev Thermal Power Plant, Ukraine; update of 110/35/6 kV substation with substitution of oil switches for gas-insulated ones at Shterovka, Ukraine; laying of KL-35 10/6 kV cable transmission line; installation and update of more than thirty 10/6 kV step-down transformers, power 630-1600 kVA.
In 2005 the company established engineering department for electric network facilities to be updated. The department prepared update engineering documentation for: substation 110/35/10 kV at Yagotyn, Ukraine; substation 110/35/10 kV at Fastiv, Ukraine; substation 110/35/10 kV at Zhuliany, Kiev, Ukraine where oil switches were substituted for gas-insulated ones, 35 kV, 10 kV switches were substituted for vacuum ones; substation 35/10 kV at Liudvynivka, Ukraine with replacement of power transformers; substations 110/35/10 kV at Boryspol, Irpen, Vasylkiv, Obukhiv in Ukraine; substation sectionalizing was engineered for twenty substations 110/35 kV in Kiev Region, Ukraine.
After 2006 Elektroyuzhmontazh LLC performed updates of substation 154/35/10 kV at Andriivka, substation 330 kV at Molochansk with substitution of high-voltage transmission line protection, at Chernihivka substation 154/35/10 kV in Zaporozhye Region, Ukraine. We replaced gas-insulated switches 110 kV of substation 110/35/10 kV at Zhuliany, Kiev, substation 110/35/10 kV at Yagotyn, substation 110/35/10 kV at Fastiv; two 6 MVA transformers with update of 10 kV outdoor switchgears, substation 35/10 kV at Liudvynivka, substituted 110 kV oil switches for gas-insulated ones with update of 10 kV indoor switchgears, substation 110/35/10 kV at Fastiv, substation 110/35/10 kV at Boryspol, substation 110/35/10 kV at Irpen, all Kiev Region, Ukraine. At the latter substation equipment was installed for reactive component compensation at 10 kV side. For Luhansk Power Association we organized exact recording at eighteen 110 kV and 35 kV substations.
In 2008 the company engineered basic oil supply system for substation 110/35/10 kV at Ros, Kiev Region.
For Luhansk Power Association we engineered update of substations 110/35/10 kV at Krasnodon, Shterovka, substations 35/10 kVat Lenin Factory, Krasnyi Yar, 6 kV indoor switchgear at substation 110/35/6 kV Kadievka, 27 projects of exact recording, update of transmission lines 0,4 kV and 6-10 kV.
For Central Power Company several engineering projects were made in update of substations, laying of air and cable transmission lines 0,4 kV and 6-10 kV.
At Turboatom plant, Kharkov we performed maintenance of plant department power equipment.
At Lightning Research and Design Institute, National Technical University Kharkov Polytechnic Institute, Ukraine we maintained electric field forming system of high-voltage test unit.
At Northern Power System of National Power Company of Ukraine outdoor switchgear 330 kV was updated.
In November 2009 Elektroyuzhmontazh Open-type Joint-stock Company was reorganized as Elektroyuzhmontazh Limited Liability Company.
In 2012 the company was absorbed by Concord Engineering group.