module bonding for wood mounting structure

I have a situation where I have an array mounted to wood framing members. I am trying to find a quicker/cheaper alternative method for bonding the panels together than mounting a lug to each module.

My understanding is that WEEB type washers are tested and listed for specific rail or other mounting systems. I dont believe it is acceptable to but one between a wood framing member and two modules.

What about using a regular top down to rail type clamp, but not using it to fasten the panels to anything, just use it to bond two panels together? I would need some sort of washer on top of the bottom T to span across the bottom of two panels.

Are crimp on ring terminals acceptable for damp/wet locations? I cant see any way around using #6 considering 250.120(C). That wouldnt really be any less work than a lay in lug on each panel however.
 

Carultch

Senior Member
Location
Massachusetts
I have a situation where I have an array mounted to wood framing members. I am trying to find a quicker/cheaper alternative method for bonding the panels together than mounting a lug to each module.

My understanding is that WEEB type washers are tested and listed for specific rail or other mounting systems. I dont believe it is acceptable to but one between a wood framing member and two modules.

What about using a regular top down to rail type clamp, but not using it to fasten the panels to anything, just use it to bond two panels together? I would need some sort of washer on top of the bottom T to span across the bottom of two panels.

Are crimp on ring terminals acceptable for damp/wet locations? I cant see any way around using #6 considering 250.120(C). That wouldnt really be any less work than a lay in lug on each panel however.
One issue you run in to with module-to-module bonding methods in general, is that the NEC requires your bonding path to be continuous, even if any of the modules are removed. No one module can be the sole link, connecting any other two modules. So if you have a row of modules, you would have to bond it to the EGC or to something else, at both ends. If you have two rows of modules, and you matrix bond among all of them or form a complete ground loop among all of them, then you can meet this rule by bonding just two of them, even if they are both on one end.

Dynoraxx has this method for bonding adjacent modules to each other. A jumper that has tooth-lock clips on both ends. Whether they will sell it to you as an individual component. I would not be able to say.
https://dynoraxx.com/grounding/dynobond/

If you did use a toothed module clamp between modules, without a rail or racking system below it, and just a washer in its place, you would certainly get your electrical continuity, but you would not necessarily be using the product within the listing instructions, which would bring up a host of other issues.
 
One issue you run in to with module-to-module bonding methods in general, is that the NEC requires your bonding path to be continuous, even if any of the modules are removed. No one module can be the sole link, connecting any other two modules.
I was not aware of that. What is your code reference? The closest thing I find is 250.148(B), but IMO that doesnt apply.
 

pv_n00b

Senior Member
Location
CA, USA
One issue you run in to with module-to-module bonding methods in general, is that the NEC requires your bonding path to be continuous, even if any of the modules are removed. No one module can be the sole link, connecting any other two modules. So if you have a row of modules, you would have to bond it to the EGC or to something else, at both ends. If you have two rows of modules, and you matrix bond among all of them or form a complete ground loop among all of them, then you can meet this rule by bonding just two of them, even if they are both on one end.
That requirement was in 2014 NEC 690.48 and it was deleted from the 2017 NEC. Anyone know if it just moved? I can't find it in the 2017 690.

OP, you might want to look at how the new FRP mounting systems are doing bonding. Since they are plastic they will have the same issues you are having.
 
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