The maximum unsupported length of an e-chain depends on the selected series and the additional weight. You can find whether a combination of selected e-chain and additional weight will work can be found in the FLG/FLB graph belonging to the series.
Here is an example for the E4.42. series:
If the additional load is 10 kg/m, the longest unsupported length in FLG is exactly 2 metres. In FLB we can load up to 20 kg/m on the unsupported length of 2 metres.