THere is no specific bonding point in the service panel that I can see. There is the terminal strip that the white neutral wires connect to, but that is it.
If this is the service panelboard, the neutral bar has a special screw which connects the grounding bar to the panelboard enclosure. That is called "binding". The neutral wires and the green equipment grounding wires all go there.
That's for services.
If it is a sub-panelboard, then there must be two neutral bars, one which is for the neutral, and is NOT bonded, and one which is for the equipment grounding wires, and IS bonded. It is required to carry the neutral all the way back to the service panelboard, where it is finally attached to the bonded grounding bar.
Hmm. Wrong ng. I think that was supposed to be bonding.
Jim
================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================
The grounding bar is always attached to the enclosure. In the service entrance panelboard, a special screw is used to bond the grounded bus (neutral bus) to the enclosure. Grounded and grounding have distinct meanings in the NEC.
GroundED: also known as - Neutral, white wire, common, return. This is a conductor that is connected ("bonded") to the body of the service entrance panelboard (often with a special screw that connects the neutral buss to the steel case). These groundED conductors carry load current back to the service entrance, and are only connected to the grounding wires at that point.
GroundING: also known as - Ground, green wire, personal protection ground, earth. These conductors do not carry current in ordinary operation but instead provide a path for leakage or fault currents in the event of equipment failure. If the fault currents are large enough the overcurrent protection should trip at the panelboard. Because no current flows in them they keep the exterior of all the equipment connected to them at the potential of the service entrance ground, which is often a driven electrode by code.
Jim
================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================
Usually two, and preferably the water main/metallic well casing and a driven electrode, as well as other possibilities in commercial/industrial buildings. The main reason for not bonding the grounded conductor and the grounding conductor beyond the service entrance disconnect/panel is if you have a bad neutral the grounding conductor will pick up the slack. If the grounding conductor is a metallic conduit it will heat up at the fittings and could cause a fire. A more subtle problem is that the grounding conductor would serve as a parallel path to the neutral, even if the neutral was good. This would cause an elevated voltage relative to ground equal to the voltage drop in the grounding conductor.
According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor with a motor designed for 230v AC on a 208v circuit. IR sells a special 208v motor for those installations. You have to order it with the correct motor on it.
We've tried using the standard 230v motor and had problems with them overheating and shorting out. It will run for a while, but eventually the motor will fail.
We are seeing more and more 208v in our area instead of 230v. I'm not sure of the reason, but most newly constructed areas are being serviced with
Buck/boost transformers are small and inexpensive, two of them will solve the problem there.
Jim
================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================
You are nuts to get your electrical wiring information from this group. In the past some of the information I've seen posted is downright dangerous, a lot is just plain wrong, some misguided, some pertains to other jurisdictions or situations or is out of date, some makes no economic sense. A small part is good sound advice from knowledgable professionals who are up on current code. So how do you sort it out? Hire an electrician.
On Sun, 07 Dec 2003 05:57:31 GMT, Ted Edwards put forth the notion that...
From my observations, that's usually because the guy with the license isn't actually doing the work... he's hiring a bunch of twenty-something year old's who think they're electricians, and he's not supervising the job properly. Sometimes incompetence is actually profitable. A good example is the electrical repair business. The guys that do troubleshooting and repair usually charge by the hour. Who makes more money, the guy who knows what he's doing and can find a problem in under half an hour, or the guy who hasn't got a clue, and spends the whole day pulling every outlet in the building apart until he stumbles upon the problem?
I know what you're saying... the advice you get on Usenet is often worth exactly what you paid for it. On the other hand, there are people out there who know what they're talking about and don't mind helping people. If you get enough answers from enough people, you can get a pretty good idea as to who knows what they're talking about and who's full of shit.
On Sat, 6 Dec 2003 10:24:57 -0500, Rick wrote (in message ):
Rick, That is not news I want to hear. This goes for running 230VAC single phase on 208VAC single phase service? I had always thought there was some lattitude in voltage ratings of motors. Can anyone elaborate on why this would cause overheatng/shorting? Trying to learn something along the way.
On Sat, 6 Dec 2003 15:12:08 -0500, Mike wrote (in message ):
Mike, I appreciate your admonition: with enough input I think the resolution(s) rise to the top of the heap eventually. It may take a little debate to get there, but often a few heads are better than one, and there are many knowledgeble folks on these newsgroups. In fact, a few years ago when I was first exploring electronics and wanted to design a digitalyl controlled circuit, an electrical engineer emailed me and it started a very intense email education...the man is brilliant and knew his stuff....one of the greatest learning experiences of my life. What you say can be true, but there are also some smart, informed , and experienced folks on here. I'll wait till I get the doubts ironed out and get consensus, then go forward. Cheers,
On Wed, 3 Dec 2003 11:27:06 -0500, Anthony wrote (in message ):
To reiterate: I am clear on this above wiring scheme except for one detail. The panel I am starting from is a subpanel and it does not contain any grounding bar or grounding terminal. In this case, does my ground wire need to be bare, or will green insulated work just as well? I pull red, black, and green insulated ground (all 10awg). Red goes to one pole of 30A dual breaker, black goes to other pole of breaker, for ground I drill a hole into the subpanel box itself then scrape some paint away and screw in a copper grounding lug. I run these three wires through BX cable to a 30AMP rated disconnect box, making certain to affix the ground to the disconnect box via a screw and to acheive good continuity. THese 3 wires exit the disconnect box and are encased in liquid tite flexible metal conduit which goes to the compressor motor/switch. Again, black and red connect to respective lugs on the motor and the ground goes to ground lug on motor.
[If I find out a boost transformer is absolutely needed to boost my 208VAC service to run the 230VAC motor, I will research that and add it t the system]. If I wish to install a 120VAC recep box in the same room as the compressor, it must be on a seperate ciruit with a dedicated breaker, NOT off the hot wires used in the compressor circuit.
The only other modification I can forsee doing to this compressor circuit would be to install a 230VAC receptacle in the wall and a mating 230VAC plug/cordset [10awg, 3 wire: red, black, green] on the compressor .... and run that downstream from the disconnect box as an option instead of the hardwired liquid tite flexible metal conduit.
What do you think guys, does that sound like it confirms to code? Thanks.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.