On 7/26/2011 3:10 PM, David Billington wrote:

Which elements did you buy. The ones I'm used to have an outer metal
sheath which is insulated from the internal heating element
and it's advisable to ground the outer sheath in case of a short, rare
but it does happen. For item such as glass annealing ovens this also
saves having to have an isolation switch to turn off the power to the
elements when the door is opened which would be required for safety with
bare wire elements.

I got two of these-
part# 3540K36
36" long x .260" dia - 120VAC 750W - 36.45 each

I just poked around on them with a voltmeter and the outside is
isolated. Testing against one end and the sheath = open circuit, while
across both the ends is 19.7 ohms.

I saw the ceramic end caps and just assumed it had to be mounted only by
them.