ceramics the spacer keys 810 may include a first outer section 840 and a second outer section 841 which may be on opposing sides of and may be attached to an intermediate section 845 as shown in some arrangements the intermediate section 845 may include a shoulder 815 although in other arrangements the intermediate section 845 may be but is not limited to being substantially similar to intermediate sections described previously herein each of the first outer sections 840 may be dimensioned to be received within the respective spacer portions 805 a 805 b as shown the first outer section 840 may be a hollow tube although in other arrangements the first outer sections 840 may be but is not limited to being arranged in a manner similar to the outer sections such as any of the outer sections described previously herein as further shown each of the second outer sections 841 may have a length that may act as a shelf for supporting the respective corner tongues 864 the second outer section 841 may further have a thickness along at least a portion of the width such that the second outer section 841 may overlap with a portion of the corner section 862 of the spacer corner 860 to provide an exposed surface along a portion of the spacer frame the respective spacer keys 810 may be made of insulative materials such as but not limited to those described with respect to the spacer key 110 in this manner the spacer keys 810 may prevent electrical shorting between the busbars 33 and 34 in the event of.