Light boxes to angled c-purlin

[ahardaway]

I am going to install some ufo led bay lights in my shop. They come with those cable hanger but if like to mount them to a junction box. The issue is the rafter purlins are angled to the pitch of my roof. Should I just use washers as a spacer to get the box to mount straight down or do they make something to correct this issue.

 

[dave*99]

Some models can generate some heat, be sure mounting them to a box is allowed by the manufacturer. Cable mounting allows for better air circulation.