This section contains general regulations and the regulations for mains and operating voltage. It also provides important information regarding your own safety and that of the entire plant.
The warning triangle to the left means that observance of all relevant regulations and notes is mandatory. If ignored, injury to persons or damage to property may result.
Observe the following regulations during engineering and project execution:
Electrical and high-voltage directives of the respective country
Other country-specific regulations
House installation regulations of the respective country
Regulations issued by the utility
Diagrams, cable lists, disposition drawings, specifications and instructions as per the customer or the contractor in charge
Third-party regulations issued by general contractors or building operators
The electrical safety of building automation and control systems supplied by Siemens depends primarily on the use of extra low-voltage with safe isolation from mains voltage.
Depending on the type of extra low-voltage earthing, a distinction is to be made between SELV and PELV as per HD 384, “Electrical plants in buildings“:
Unearthed = SELV (Safety Extra Low Voltage)
Earthed = PELV (Protective Extra Low Voltage)
G0 (system neutral)
Observe the following for grounding G0:
As a rule, earthing and non-earthing of G0 is permissible for AC 24 V operating voltage. Decisive are the local regulations and customary procedures. For functional reasons, earthing may be required or not permissible.
AC 24 V systems should always be earthed if this does not contradict the manufacturer’s specification.
To avoid earth loops, systems with PELV may only be earthed at one point of the system, normally by the transformer, unless otherwise specified.
AC 24 V
With regard to AC 24 V operating voltage, the following regulations must be complied with:
AC 24 V
The operating voltage must comply with the requirements for SELV or PELV:
|Specification on AC 24 V transformers||
AC 24 V operating voltage
Secondary side of transformer: