Experiments have been carried out at JET to determine the influence of the toroidal field direction on L-mode and H-mode plasmas. These included divertor and SOL physics [1] and H-mode physics studies. In this paper we describe the results concerning the influence of toroidal field direction on H-mode plasmas and ELM energy losses, as well as on the operational space of ELMy H-modes. The parameter range explored in these experiments was : plasma current Ip = 1.2-3.0MA (with q95 = 3-3.6), additional heating (NBI and NBI +ICRH, dominated by NBI) PINPUT = 9 ­ 17MW and with various levels of gas fuelling. The discharges had magnetic configurations optimised for ELM power load (DOC-L) and edge pedestal gradient measurements (DOC-U) with an average triangularity d ~ 0.3.