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This article describes the importance of including repair of the grounding conductor (ground wire) in buildings where where solid conductor aluminum electrical wiring is being repaired. This article series describes the acceptable methods to repair aluminum wiring, including which aluminum wire connectors to use for safest results.
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Readers faced with limited space in the electrical boxes of an aluminum-wired building ask if it is acceptable to just pigtail the current carrying conductors - the "hot" and "neutral" wires, leaving the aluminum ground wire alone.
Our photo (left) shows an improper aluminum wiring repair - the white twist-on connector is not recommended for this application. Thanks to Dr. Jess Aronstein for clarifying this question with the comments below.
The electrical ground is part of the electrical safety system and must be capable of carrying current under various fault and malfunction conditions.
The probability of any wire termination or splice of a ground conductor actually carrying substantial current is low relative to the circuit conductors (line and neutral), but not low enough that it can be ignored. That is why modern codes require full-size ground conductors.
The Installation Instructions for the AlumiConn™ include using copper pigtailing and an AlumiConn connector for the solid conductor aluminum ground wire, handling it just the same as the aluminum hot and neutral wires.
For the specific case shown at left (connection of a ceiling fan), King Innovations points out that ... in the application shown the use of "pigtails" is not required.The aluminum wires and fan can be directly wired to the AlumiConn connector.
However, if the installer is wiring a device such as an electrical switch or receptacle (a more common situation), pigtails would be needed.
Using the AlumiConn for aluminum ground wire repairs
In our version of the AlumiConn™ wiring sketch (left) the incoming solid aluminum ground wire is visible in silver connected to the top terminal in the AlumiConn™ connector - any terminal on the AlumiConn can be used to receive either an aluminum or a copper wire.
Notice that we show two solid aluminum (silver colored) and one solid copper (copper colored ) ground wires leaving the connector.
To avoid clutter we didn't color the hot and neutral wires, but the same procedure as described above would apply to those elements of the circuit as well.
The AlumiConn™ connector shown here is used to splice a copper "pigtail" wire together with one or two aluminum wires as a step in reducing the fire hazard associated with aluminum electrical wiring. This connector performs well provided that the wires are properly secured in the connector, and it has been included in the US CPSC recommendations for aluminum wiring repair.
See AlumiConn ALUMINUM WIRE CONNECTORS for a description of how the AlumiConn™ is connected, wired, and torqued.
Questions regarding electrical code issues are best answered by your local electrical inspection authority, since applicable interpretations vary. In the long run, you should use what is presently listed for the application or what the local electrical inspection authority and your insurer will sign off on.
Because the reader was considering using twist on connectors where the recommended aluminum wiring repair connectors may not fit (not a procedure that we recommend) we strongly advised that he employ the special procedure (wire abrasion under a film of inhibitor, and pre twisting) as described at Reducing the Fire Hazards in Aluminum Wired Homes.
In the financial analysis of the cost of performing a complete and proper repair of aluminum electrical wiring, be sure to include consideration of the possibility that a repair considered to be permanent (CPSC --COPALUM) could have some long-term payback through the value that it adds to the property.
Detailed Advice for Aluminum Ground Wire Connections during Aluminum Wire Repair in buildings
Is it necessary to use a rated "pigtail" connector, such as the Alumiconn or COPALUM connectors, on the grounding circuit given that the ground only carries current if and when a fault occurs? It would save considerable money, and space in the fixture box, to use those rated connectors only on the hot and neutral wires which regularly carry current.
The question of how to handle the grounding conductor in aluminum wired homes arises from time to time, especially because in some installations of crowded wiring in junction boxes, people want to leave out the ground pigtail connection. Dr. Jess Aronstein, expert on aluminum wiring failures, testing, and repair procedures, in discussing this topic, has noted that:
The US CPSC publication on Aluminum Electrical Wiring specifically says that the main criteria to be met by such a repair method are:
In our [DF] non-nexpert-opinion, even though ground wires do not normally carry current, mechanical stresses and potentially loose connections remain, leading to a view that it may indeed be preferable to use a copper pigtail when connecting an aluminum grounding conductor to a device such as an electrical receptacle or light switch, and as well when making a connection between the grounding conductor and a metal junction box, say using a grounding screw sold for that purpose.
Frequently Asked Questions (FAQs) About Repairing the Ground Wire in Aluminum-Wired Homes
Question: Can I Use Twist-on Connectors for Aluminum Ground Wires?
If you do use any twist-on connectors (we and the US CPSC specifically do not recommend this approach, including we do not recommend use of the Ideal-65 "twister" purple twist on connector sold for aluminum wiring repair), we strongly advise that you employ the special procedure (wire abrasion under a film of inhibitor, and pre twisting) as introduced at http://www.inspectapedia.com/aluminum/Aluminum_Wiring_Risk_Reduction.htm and described in more detail in the report "Reducing the Fire hazard...." found at http://www.inspectapedia.com/aluminum/alreduce.pdf
In the financial analysis of the cost of aluminum wiring repair for large buildings, it is important to consider the possibility that a repair considered to be permanent (COPALUM or the Alumiconn) could have some long-term payback through the value that it adds to the property.
Best Practices Guide to Repairing Aluminum Ground Wire Connections
All aluminum wire conductors should be repaired, including the aluminum ground wire.
Since the electrical ground wire is not normally carrying current it may be that aluminum ground wire connections might be in better shape and at lower risk of failure than other wires in an AL wired circuit. BUT
Two Connectors Recommended for Repairing Aluminum Wiring, including Ground Wiring
Question: How Can we Address the Problem of Limited Space in the Electrical Junction Box?
Two comments about the space problem inside the junction box:
NEC has made an exception to standard cu. in. space requirements per number of conductors to make it a little easier for an AL wire repair to meet code
When we had a space problem in junction boxes at a rewiring job we purchased box extenders - some suppliers call them "sidecars" that allowed me to extend the size of each metal junction box in the building by removing the exposed side plate of the box and screwing on the extender that gave a few more cu. in. of working space to push wires back into the box. This might mean cutting and patching drywall wherever this was needed at receptacles and switches.
At an actual 4" square junction box there are also box extenders that increase the total box depth - but that fix means loosening and then re-securing the box so that its face remains flush if it's showing in an interior space. In an attic or basement or other unfinished it should be possible to extend the box sizes without the cosmetic repair issue.
Another approach could be thinner (front to back) receptacles. They do vary a bit from brand to brand and model to model.
Space taken up by aluminum wiring repair connectors
Solutions to the problem of jamming those additional connectors into an existing electrical box are at ALUMINUM WIRE REPAIR SPLICE SPACE
Just tighten the existing aluminum ground wire connections?
A general worry is that whenever we do any repair on a building safety topic that is less than the recommended or optimum procedures, the risk picture is foggy - people think that the issue has been "fixed" so they forget about it - which can lead to someone ignoring danger signals and later having a problem.
Question: What About Other Aluminum Wire "repair" Products such as CO/ALR devices?
Please see ALUMINUM WIRING REPAIR NOT-Recommended for details.
Question: Do the grounds on an electrical receptacle also need to have an AlumiConn Connector or Just the Hot and Neutral
When using alumiconn connectors to pigtail plugs and switches, do the grounds on a plug also need to have a AlumiConn as well or just the hot and neutral? Thankyou! J.H.
Basically, yes you need to use a connector for EVERY wire that enters as aluminum and connects to something else, including the aluminum ground wire.
So the aluminum ground wire that enters an electrical receptacle box gets pigtailed to a short length of copper wire (the pigtail). That copper pigtail in turn completes the connection of the incoming ground to the electrical receptacle "box") itself as well as to the electrical receptacle - the device you refer to as many do as "the plug".
If your receptacle box is not the last one in a daisy-chain of receptacles, you'll see that there is (or should be) also an aluminum ground "leaving" the receptacle box and heading for the next box in the chain. You should not need an additional copper pigtail for that connection: each AlumiConn terminal block provides three points of connection. So as you'll see in King's illustration (reproduced with color cues on our web article), the three connections in the AlumiConn used to wire the ground will be used to receive (one-wire each) the following:
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