MH Ballast

[mike31154]

For good advice it would be helpful to know what type of ballast it is, electronic or core & coil. I would think for an electronic one it makes little difference so I'm guessing what you have may be a coil & core or magnetic ballast. If so, the transformers are very heavy and may only be attached to the housing bottom with light hardware. If you were to mount that upside down or sideways, the hardware may fail & the xformer would come loose. The other issue, as mentioned may be for efficient heat dissipation.