FIREBOX: Confined Spaces is a question that often comes up when discussing fire-rated compartments with metal load-bearing structures. Here you’ll find a clear and practical answer, including the criteria and practical implications for those working inside.
Table of Contents
What Are “Restricted Conductive Areas” (RCA)?
“Confined conductive areas” (LCR) are addressed in CEI 64-8/7, Section 706, and are referenced in the CEI 64-17 Guide on the installation of electrical systems at construction sites.
In practice, the term “LCR” is used when the environment—due to its materials and dimensions—increases the likelihood and duration of bodily contact with conductive parts, thereby making the electrical hazard more critical.
When a Place Is a “High-Risk Venue”: The Criteria
A place is defined as a confined space when the following conditions are met:
- It is bounded by metal or conductive surfaces.
- Its size is such that it restricts the operator’s movement and is likely to come into contact with large parts of the body (other than the hands and feet).
- The ability to interrupt such contact is limited.
These three elements must be considered together: it is not enough for there to simply “be metal present”; it also matters how much the space constrains the operator and how realistic it is that the contact would be prolonged and difficult to break.
Typical examples of narrow conductive areas
The following are considered confined conductive spaces, for example:
- cisterns or small metal tanks;
- inside metal pipes;
- metal or damp tunnels;
- limited excavation of the ground;
- cavities within non-insulated structures, large enough that anyone entering them to work is in constant contact with the walls.
These examples help illustrate the logic: the operator is “confined” in the space, and contact with conductive surfaces is likely, extensive, and prolonged.
FIREBOX and “restricted conductive areas”: when we’re NOT talking about LCR
In general, the following are NOT considered confined spaces:
- FIREBOX-type prefabricated structures;
- metal scaffolding;
- the major platforms;
- the large metal silos.
This point is at the heart of the matter: even if a space contains metal elements, that does not automatically make it an LCR. If the conditions of a “confined space” and extended, difficult-to-interrupt contact are not met, the space does not fall under the definition of a confined conductive space.
What’s Changing in Electrical Safety: General Rules vs. Specific Measures
When you are not in an LCR (for example, in FIREBOX units), simply follow the general rules for electrical safety.
The practical consequence, put simply, is this: if FIREBOX units are not “confined conductive spaces,” it is not necessary to follow the specific protective measures against direct and indirect electrical contact required for LCRs.
What measures are specified in the LCR (SELV and electrical isolation)?
Specific protective measures against direct and indirect contact are provided for LCRs in the circuits they power:
a) portable tools and measuring instruments or other transportable or movable components
b) portable lamps
c) fixed electrical components
In LCR circuits, protection against direct and indirect contact can be achieved by means of:
- SELV (Safety Extra-Low Voltage) circuits: circuits operating at a supply voltage (between phase and ground) of less than 50 V AC or less than 120 V DC;
- Electrical isolation: achieved by using an isolation transformer between the power grid and the electrical appliance.
If, on the other hand, you are in a FIREBOX (which, as noted above, is not an LCR), the operational conclusion is that neither safety transformers nor isolation transformers are necessary, as these are “LCR-specific” measures.
Technical Conclusion: FIREBOX devices are not LCR (and what that means)
To summarize the key points:
- The definition of LCR requires a confined space + probable or prolonged contact + difficulty in breaking off contact;
- Examples of environments that are generally not LCR include prefabricated structures such as FIREBOX;
- Therefore, FIREBOXes are not “confined conductive spaces” (LCR);
- Consequently, it is not necessary to implement specific LCR measures (such as safety or isolation transformers) simply because the equipment is operating in a FIREBOX.
Training and Qualifications for Operating a FIREBOX (PES, PAV, PEI)
However, there is one aspect that should not be overlooked: the FIREBOX contains electrical systems and electromechanical components that must be connected to the power grid in order to function.
Operators assigned to work inside the FIREBOX, in presence or absence of power, must be properly trained. Please note that:
- The employer is required to provide all workers with adequate training to ensure full compliance with safety rules and to prevent serious or fatal accidents;
- CEI 11-27 defines the minimum training requirements for various roles.
The figures shown are:
- Qualified Person (PES): capable of performing electrical work on live circuits.
- Trained Person (PAV): May perform work near live parts.
- Qualified Person (PEI): performs work on de-energized equipment and in the vicinity of electrical hazards.
In addition, Legislative Decree 81/08 CEI 11-27 stipulates that electrical work on live parts or parts that are temporarily de-energized must be performed by qualified personnel who are aware of the hazards associated with electrical risks and who meet the requirements for working on live parts.
Conclusion
FIREBOX units generally do not fall under the definition of “confined conductive spaces”; this means that the general electrical safety rules apply, rather than the specific measures required for confined conductive spaces. In any case, the training and qualification of personnel working inside these units remain essential.
