# Application Assessment of Electrical Cables during Smoldering and Flaming Combustion
## 4 Conclusions  
The presented results confirm the significant influence of combustion method on detector activation times for the cable samples. From the analysis of the measurement results, it can be concluded that the highest smoke concentration (Y) in the test chamber was achieved during flaming combustion. The highest extinction modulus values were measured during smoldering combustion initiated by the heating plate. The response time of the fire detectors was significantly influenced by the size of smoke particles and the rate of increase in their concentration. During flaming combustion, the smoke particles reached the fire detectors faster. The results obtained are consistent with data reported in the literature: optical smoke detectors are more sensitive to smoldering than flaming combustion. Only the suction system (detector 6) was able to detect all the test fires due to its having the most complex optical system.  
Moreover, the characteristics of the cable insulation material, e.g., PVC type, had a significant influence on the toxicities of the emitted gases. The largest amounts of toxic gases were released during the smoldering combustion of cable B, which had a plasticized PVC sheath. This proves the high contents of various flame retardants and plasticizing additives compared to other cable sheathings made of plasticized PVC which do not emit such quantities of gases. The toxic gas for which the highest concentrations were observed was carbon dioxide, during smoldering combustion initiated by the flow of electric current. The release of CO began after about 240 s, and the maximum CO value was obtained for wire H (PVC). In contrast, during smoldering combustion initiated by the flow of electric current through the wires, wire C (mica tape banding and halogen-free plastic) began to burn from the inside earlier than the others. In the case of flame combustion, the increase in CO concentration was the fastest, and the lowest CO concentration values were observed during smoldering combustion initiated by the flow of electric current through the wires. The location of the fire detectors had an impact on the detectors' activation times. Linear detectors should be mounted close to the ceiling. The obtained test results clearly show that the mode of combustion, i.e., smoldering or flaming, has a very large impact on the response time of detectors. The construction of the cable and the insulation material also had impacts on the results. In addition, the place where a detector was installed in the combustion chamber and the detection method used affected the detector's fire detection time.  
Conceptualization, R.P., M.Z. and P.S.; methodology, P.S., M.Z. and T.P.; software, R.P., P.S. and J.G.; validation, R.K., P.B.-P. and P.R.; formal analysis, P.R.; investigation, P.B.-P. and P.S.; resources, P.S., R.P., P.B.-P. and A.C.; data curation, R.K. and A.L.; writing--original draft preparation, R.K. and R.P.; writing--review and editing, R.P., A.L. and R.K.; visualization, R.P.; supervision, J.G. and A.L.; project administration, R.K. and P.B.-P.; funding acquisition, P.B.-P. All authors have read and agreed to the published version of the manuscript.  
This paper is the result of research project in frame of IDUB programme at AGH University of Science and Technology, Poland. The APC were funded by the Programme of the Polish Ministry of Science and Higher Education, the Regional Initiative of Excellence, financed by the Polish Ministry of Science and Higher Education on the basis of contract no. 025/RID/2018/19 of 28 December 2018; the amount of funding was PLN 12 million.  
Not applicable.  
The authors declare no conflict of interest.