It has been found that the L-mode density limit was decreased when going from the open MkI divertor to the closed MkII divertor. But simultaneously the wall temperature was increased from 40°C in the MkI divertor to 220°C in the MkII divertor. In order to disentangle the effects of the wall temperature and the divertor closure on the density limit new experiments in the JET gas box divertor, which is even more closed than MkII, have been carried out. The density limit is compared for 320°C and 200°C wall temperature, meaning 220°C and 140°C divertor target plate temperature. Additionally different configurations, which differ in the strike point heights on the vertical divertor targets and consequently leading to open and closed divertor configurations, were investigated.