Testerguy
Member
- Location
- Oakland, CA, Alameda
A friend wants to install a 3.3kw charger for his new Chevy Volt. His detached garage has a single 120v/20a circuit for lighting/outlet/door-opener fed by a hot/neutral 12ga pair in 1/2" conduit (with the conduit acting as the Equipment Grounding Conductor) . Running a new feed is expensive due to terrain/concrete stairs in the way, and the electrician on the job is somewhat reluctant to try pulling additional wires in the existing conduit (presumably due to the number of tight bends). One solution under discussion is to convert the existing circuit to 240v. The charging system can be configured for a variety of current draws, including 12a or 16a, so the existing 12ga is sufficient. In order to preserve the 120v for the lighting, convenience outlet and garage door opener, the plan would be to install a 240-120v transformer fed off the converted 240v circuit.
The challenge is meeting safety and code requirements for grounding and bonding, preferably without installing a separate grounding electrode and/or pulling any new wires. Is there a safe and code-compliant way to accomplish the above by utilizing the existing conduit as the sole grounding pathway (essentially as both the GEC and the EGC) back to the primary panel, where there is a proper bonding connection between the source neutral and the home's grounding electrode?
It would seem to be safe to do so (assuming that one does a rigorous inspection of the integrity of the grounding path through the conduit, tightening all connections etc), but I have reviewed NEC section 250 (2008 and 2011) regarding SDS, Grounding, and Bonding and am having trouble determining if it is code-compliant (quick reading suggests it is not). My question is two-fold:
1) Is there a way to do this that is code-compliant
2) If it is not to-the-letter-compliant does anyone know of an actual real safety issue? I do not know if the homeowner will be pulling a permit or not, but clearly wants it to be safe. If he later moves out, he could readily convert it back. I supect, though, that he will not proceed unless it is code compliant in addition to being safe.
If this is a non-flyer, what's the minimum to make it compliant (exterior grounding electrode, pull a bare grounding conductor through the conduit, etc)?
THANKS!
The challenge is meeting safety and code requirements for grounding and bonding, preferably without installing a separate grounding electrode and/or pulling any new wires. Is there a safe and code-compliant way to accomplish the above by utilizing the existing conduit as the sole grounding pathway (essentially as both the GEC and the EGC) back to the primary panel, where there is a proper bonding connection between the source neutral and the home's grounding electrode?
It would seem to be safe to do so (assuming that one does a rigorous inspection of the integrity of the grounding path through the conduit, tightening all connections etc), but I have reviewed NEC section 250 (2008 and 2011) regarding SDS, Grounding, and Bonding and am having trouble determining if it is code-compliant (quick reading suggests it is not). My question is two-fold:
1) Is there a way to do this that is code-compliant
2) If it is not to-the-letter-compliant does anyone know of an actual real safety issue? I do not know if the homeowner will be pulling a permit or not, but clearly wants it to be safe. If he later moves out, he could readily convert it back. I supect, though, that he will not proceed unless it is code compliant in addition to being safe.
If this is a non-flyer, what's the minimum to make it compliant (exterior grounding electrode, pull a bare grounding conductor through the conduit, etc)?
THANKS!