grounding and bonding parking lot lighting

[inspector23]

When connecting the grounding for the light standards in a parking lot, the electrical contractor (EC) simply took a # 4 bare copper wire and properly clamped it with a UL listed clamp to the reinforcing bars of the concrete cylinder prior to pouring the concrete in the cylinder.

When it came time to hook up, the EC took the other end of the bare copper wire and attached it to the factory lug provided inside the handhold of the post. He ran two #10 AWG's from the panel to the light fixture for the 240 V system.

My understanding was he needed to have an additional wire (properly sized) to bond the pole back to the power source. His contention is he does not, citing article 410.21 (2002 code)and the definition of equipment grounding conductor.

Ideas?

[ September 23, 2005, 04:05 PM: Message edited by: inspector23 ]

 

[raider1]

Re: grounding and bonding parking lot lighting

410.21 says that a fixture is considered grounded where mechanically connected to an equipment grounding conductor as specified in 250.118 and sized in accordance with 250.122

This means he has to provide a grounding conductor, or use a metal conduit to provide the grounding path.

Just using the re-bar in the pole base will not provide an acceptable fault currant path.

Some times a job spec will require you to have a grounding electrode at each pole, but you still need a EGC.

Chris

 

[infinity]

Re: grounding and bonding parking lot lighting

I agree with Chris. If the installation had metal conduit that was attached to the light post than he would be code complaint. If he used non metallic conduit than he would need to install an EGC back to the source of the lighting circuit.

 

[inspector23]

Re: grounding and bonding parking lot lighting

He used PVC, and there was nothing on the prints indicating any additional ground rods.

Thanks for your help!

 

[stud696981]

Re: grounding and bonding parking lot lighting

I agree with the above, either pull a separate ground wire or use metalic conduit. In this case since PVC was used the only option is to pull a ground wire. If a hot conductor came in contact with the metal pole, there would not be enough current flowing on the ground to trip the OCPD. This is an accident waiting to happen. While this may have been an oversight on the plans, I don't know any electrical inspector that would pass something like this.

 

[iwire]

Re: grounding and bonding parking lot lighting

Inspector23 What you describe is very dangerous, it must be corrected. People get killed at light poles wired like that.

I agree entirely with stud696981's post.

There are a number of code sections that could be cited here but I will give just one basic and important one.

250.4(A)(5) Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a permanent, low-impedance circuit capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be used as the sole equipment grounding conductor or effective ground-fault current path.

Inspector23 please do all that you can to get this corrected, you may well save someones life.

[ September 24, 2005, 05:53 AM: Message edited by: iwire ]

 

[roger]

Re: grounding and bonding parking lot lighting

I agree with the others as well. The installation is wrong and the EC should know it.

Here is the installations dangers in a graphic from Mike Holt.

Roger

 

[dillon3c]

Re: grounding and bonding parking lot lighting

Originally posted by roger:
The installation is wrong and the EC should know it.

*These words above,ring so true..

Inspector,
In reading your past postings,knowing you to be a combination inspector. nothing wrong with that..

*But this (and being reserved in the term) electrician,is just flat dangerous Mike..If you don't mind me saying so,this should be a serious "heads-up & wake-up" call into his installations.

 

[dillon3c]

Re: grounding and bonding parking lot lighting

~button error~

[ September 24, 2005, 09:57 AM: Message edited by: dillon3c ]