Un local technique désigne toute partie d'un bâtiment destiné à abriter des éléments techniques (ascenseur, chaudière, climatiseur, commutateur téléphonique, VMC, etc.), mais aussi toute partie destiné à abriter les fils et câbles électriques (fil de terre, électrique, téléphonique, de télévision, etc.) ainsi que les tuyaux (gaz, eau, etc.), les circuits et compteurs de gaz des fluides (gaz de ville, air comprimé, eau potable, eau chaude sanitaire, chauffage collectif, etc.) permettant le bon fonctionnement d'une maison ou d'un bâtiment.
https://fr.wikipedia.org/wiki/Local_technique

Français Anglais
local technique nm (lieu pour équipement technique) plant room n
(US) mechanical room n
control room, control centre
http://www.wordreference.com/fren/local technique

local technique n.
equipment room
https://dictionnaire.reverso.net/francais-anglais/local tech...

A mechanical room or a boiler room is a room or space in a building dedicated to the mechanical equipment and its associated electrical equipment, as opposed to rooms intended for human occupancy or storage.
https://en.wikipedia.org/wiki/Mechanical_room

A control room, operations center, or operations control center (OCC) is a room serving as a central space where a large physical facility or physically dispersed service can be monitored and controlled.
https://en.wikipedia.org/wiki/Control_room

An equipment room is a room or space within a building for the storage or installation of mechanical or electrical/electronic devices.
https://en.wikipedia.org/wiki/Equipment_room

Comment: Not satisfied by these terms
Domain Building and public works
fr
Term local technique
Reliability 3 (Reliable)

en
Definition a room or space provided in a building to accomodate building service equipement such as air conditioning or heating appliances, electrical services pumps.../National Building Code of Canada, 1970 ..
Term service room
Reliability 3 (Reliable)
Term service space
Reliability 3 (Reliable)
Term mechanical room
Reliability 3 (Reliable)
http://iate.europa.eu/SearchByQuery.do?method=searchDetail&l...

Domain Land transport
fr
Definition Local contenant des équipements techniques destinés à des applications ferroviaires (par exemple, la signalisation, l'alimentation en énergie, la commande de la traction, etc.)
Term local technique
Reliability 3 (Reliable)
en
Definition room with technical equipment for railway applications (e.g. signalling, energy supply, traction control, etc.);

Term technical room
Reliability 3 (Reliable)
http://iate.europa.eu/SearchByQuery.do?method=searchDetail&l...

Service room
from RVCA Regulation Terminology (2011) by Rideau Valley Conservation Authority
Service room means a room provided in a building to contain equipment associated with building services.
https://definedterm.com/service_room

Service space
Definition
Service space means space provided in a building to facilitate or conceal the installation of building service facilities such as chutes ducts pipes shafts or wires.
https://definedterm.com/a/definition/49091

An electrical room is a room or space in a building dedicated to electrical equipment. Its size is usually proportional to the size of the building; large buildings may have a main electrical room and subsidiary electrical rooms. Electrical equipment may be for power distribution equipment, or for communications equipment.[1]
Electrical rooms typically house the following equipment:
• Electric switchboards
• Distribution boards
• Circuit breakers and disconnects
• Electricity meter
• Transformers
• Busbars
• Backup batteries in a Battery room
• Fire alarm control panels
• Distribution frames
https://en.wikipedia.org/wiki/Electrical_room

TGBT est un sigle qui désigne :

• Tableau Général Basse Tension. C'est le tableau électrique basse tension des grandes installations électriques.
https://fr.wikipedia.org/wiki/TGBT

Un tableau électrique est un tableau de répartition comportant différents types d'appareillage associés à un ou plusieurs circuits électriques de départ alimentés par un ou plusieurs circuits électriques d'arrivée, ainsi que des bornes pour les conducteurs neutre et de protection1.
https://fr.wikipedia.org/wiki/Tableau_électrique

A distribution board (also known as panelboard, breaker panel, or electric panel) is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits, while providing a protective fuse or circuit breaker for each circuit in a common enclosure. Normally, a main switch, and in recent boards, one or more residual-current devices (RCD) or residual current breakers with overcurrent protection (RCBO), are also incorporated.
In the United Kingdom, a distribution board designed for domestic installations is known as a consumer unit.[1]
https://en.wikipedia.org/wiki/Distribution_board

Low-voltage Distribution boards up to 630 A
Wall-mounted and floor-standing enclosures for electrical distribution up to 630A
The smallest distribution board of our xEnergy family is the most flexible and variable system in the entire range. The diversity of different types and sizes makes the use in almost every application possible. Thanks to its certification as low-voltage distribution board intended to be operated by ordinary persons acc. to IEC/EN 61439-1/3 as well as to IEC/EN 62208, the xEnergy B is the first choice for electrical distribution in residential and functional buildings.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&c...

Acronym Definition
LVDB Low Voltage Distribution Board (electrical engineering)
https://acronyms.thefreedictionary.com/Low Voltage Distribut...



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Note added at 14 hrs (2018-07-25 21:14:52 GMT)
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or "technical room (or electrical room) for main LVDB"



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Note added at 23 hrs (2018-07-26 06:12:16 GMT)
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Other common terms for "TGBT" are main switchboard; main control panel or main distribution board)
(Dictionary or Electrical Engineering and Electronics)

What else can it be?

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Note added at 2 days 4 mins (2018-07-27 06:41:28 GMT)
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To Tony M (added 7/27): You provided a very good explanation of why I offered no translation. LT can be pretty much anything (from an electrical cabinet to a stand-alone building or an outdoor area). In this case the latter is not an option. But LT still may be any enclosed space, and, from what I've seen in the past, may be even called an "building services room/plant/area".

French term (edited): LT

or 'electrical cupboard' — it all depends on the actual size of the place! You may be able to glean further clues from the rest of your text (dimenions, floor plans, descriptions, etc.)

Basically, if it is big enough to need mechanical ventilation, then in my book it probably qualifies as a 'plant room'.

You may want to think again about your propsoed translation for 'TGBT' — although your suggestion would certainly be right in some contexts, it sounds as if your context here may be rather larger in scale, and as such, this could well be a lot more than just a mere 'panel' — you need to try and look for clues as to how large it is and what it actually contains?

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Note added at 16 hrs (2018-07-25 22:57:13 GMT)
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There are plenty of examples of 'plant room' out there on the 'Net — here's just one that happens to mention it in a document discussing electrical installations.
Npte that in general terms, a low-voltage dis. board is often located in a (probably its own) plant room, which might or might not contain other plant at the same time.

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Note added at 1 day 3 hrs (2018-07-26 09:43:40 GMT)
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Bahrain Energy Policy Laws and Regulations Handbook Volume 1 ...

https://books.google.fr/books?isbn=1312958790
IBP, Inc. - 2015 - ‎Business & Economics
... 11,000/400 Volt Transformer(s), and low voltage distribution board(s) all of which ... or in plant room(s) immediately adjacent to the distribution substation(s).


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Note added at 13 days (2018-08-08 06:07:26 GMT) Post-grading
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In EN, a 'plant room' is a special area, usually with a more 'utilitarian' finish (and certainly not intended to be visited by the general public!) intended for housing 'plant' — i.e. any kind of technical equipment (which may or may not be electrical in nature)

This is a generic term and can refer to room-spaces of many sizes; what makes it a 'room' rather than a 'cupboard' is in essence simply whether or not you can physically walk into it. It can be used for HVAC plant, boilers, swimming-pool plant, emergency generators, computer or telecoms interconnections, etc. Hence its usefulness as a catch-all term if it is not possible or desirable to be more specific.

'plant' is a general term for any kind of 'technical equipment', and is common jargon in e.g. the building industry.