Bare copper ground wire zip tied to aluminum

[SolarEngineer]

This one stumped me today: an inspector didn

[Sunking]

Well the inspector is 100% correct, it will cause corrosion without measures being taken to prevent it like insulated copper wire. However it does not apply to the situation because your are not bonding the aluminum rack with a made electrical termination.

Unless this is multi-million dollar project worth going to court over the one thing I have learned in 33 years of working with inspectors is to just do what they want, applogize for for your ignorance and wasting his time, pay the re-inspection fee, and say thank you when he passes and signs off your job. Next job he will be easier to get along with. Fight him and every detail will be nicked picked from that point on. I promise he will win the argument and cost you a lot of money and time fighting him.

[Han Solar]

Could be OK if the aluminum rail is anodized. I find many of the rail products, even clear rails have a coating.

[andrewc]

I hope it isn't a problem to bump this thread, as I've been thinking about this one a bit lately, but didn't want to make a new topic altogeter. Due to galvanic reaction, dissimilar metals can corrode: in this case, copper and aluminum. Many racking systems use aluminum rails, and bare copper is very common for outdoor grounding. We must bond rails together for EGC purposes. We often use lugs to make the actual point of contact, with appropriate weebs or stainless steal star washers (to pierce the anodization/coating of the rails). In my experience as a low level installer, we have, in situations, zip tied the bare copper to the rail for wire management purposes, or in cases of 2+ rows of panels, taken the bare copper and hopped over the rails. Or in the case of splices, used lugs and a piece of bare copper as a jumper (as in this photo I found on the web:http://www.milestonesolar.com/images...und_straps.jpg). However, it seems like even with the jumper, and especially when jumping from rail to rail to rail, there is no sure way to keep the copper from coming in contact with the rails over the lifetime of the array (20+ years). Is the anodization really enough to protect against galvanic corrosion? Should we really be using insulated, not bare, copper on roofs? Are there better ways to route copper to minimize contact to rails? What are other people doing, and what are best practices?

[Mike90250]

Mostly, it has to do with code, and what the inspector wants. You could use 1/2 grey PVC cut into 1" sections, and attach that to the rails, and thread the copper through it.

What sort of life are you expecting for zip ties ? Are you really expecting 25+ years for them in the sun and weather on a roof?

[solarpowered]

Every inspector thinks they have a better idea than an engineer. How ever the pay grade doesn't represent that. Most inspectors have problems with their private lives, and they transpose those problems into their professional lives. Not all inspectors ar elike that but most I've delt with in the past 16 years are.

Technically the correct method for grounding copper conductor to aluminum rack is to use a stainless steel ground bond,(or pass through lug). Then here isn't the need for nolox. Terminating copper conductor ends to aluminum rack. Aluminum compression lugs with NOLOX need to be compressed onto copper conductor.

[peakbagger]

The problem with a typical installation is that galvanic action takes potentialy years to appear and the installer and original owner may be long gone. I worked in a pulp and paper mill for many years and the corrosion conditions are accelerated as its warm, damp with lots of corrosive agents in the air. When someone screwed up and set up a gavanic cell inadvertently, it would be obvious in weeks not years. Thus people learned to avoid it.