Someone told me you can ground to an empty electrical conduit. I was always taught water pipe or steel to ground in the building. Would anyone here recommend using an empty electrical conduit as a ground? I think I am having nothing but problems since the maintenance staff did it to the conduit and am thinking of unhooking it in the am.
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Grounding to empty steel electrical conduit 1
- Thread starter phonesaz
- Start date
Here is a good discussion about system grounding.
A former contributor to Tek-Tips provides excellent insight into a problem that can develop if you ground to building steel.
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"FEATURE 00
A former contributor to Tek-Tips provides excellent insight into a problem that can develop if you ground to building steel.
I
"FEATURE 00- Thread starter
- #3
My questions are:
What do you think?
Do you think the conduit is a "ground" unto itself?
Is the conduit connected to anything?
Do you really understand electricity?
If it was properly connected to a main reference ground/bond termination point at the service disconnect, it could be used an equipment grounding conductor. You might want to read the NEC sections that cover this subject matter.
....JIM....
What do you think?
Do you think the conduit is a "ground" unto itself?
Is the conduit connected to anything?
Do you really understand electricity?
If it was properly connected to a main reference ground/bond termination point at the service disconnect, it could be used an equipment grounding conductor. You might want to read the NEC sections that cover this subject matter.
....JIM....
- Thread starter
- #5
I think - it could be a ground (should be?) if it is connected to the building steel structure that is grounded. It appears to be. I am not an electrician. I understand enough about electricity to change a light fixture but that is about it. I have read the NEC code book and actually am taking a refresher course on the 2011 changes at my local community college starting tomorrow of course.
What prompted this thread...
One of my recently inherited customers has an old Toshiba that has random line noise. The carrier is blameless of course and suggested checking the ground. I at the same time installed a MultiTech 4-port fax finder, which is not cheap and requires a ground to not void the warranty. Pointing both of these issues out to the customer resulted in a ground wire being provided that is grounded off a hard metal electrical conduit to a ground bar. I grounded the PBX and the Fax Finder to the ground bar that was provided and have had more fax failures (almost 25% of the total) and line noise complaints since it was installed that in the prior 9 months I have known them. The fax failures are on two existing fax servers that have been in place for quite a while so we have a history of their performance.
The carrier in this case is not a good one and has a really bad rep so maybe they were just having a bad day. Or I was running through all the changes that had been made in the last couple of days and realized the ground is new. If they are having difficulties again this AM I am going to go out and remove the wires and see if the failures subside. If so I am just going to have them buy a couple of those DiTek (?) boxes, which I have used before, and go from there.
My biggest failure is I don't have appropriate equipment to test for ground. We have evolved from a telephone install/programming shop to a little bit of everythig shop; thus the NEC refresher course. Back in the day when everyone had $$ we could just tell the customer to have their electrician provide a ground and get back to us... not quite so easy any more.
What prompted this thread...
One of my recently inherited customers has an old Toshiba that has random line noise. The carrier is blameless of course and suggested checking the ground. I at the same time installed a MultiTech 4-port fax finder, which is not cheap and requires a ground to not void the warranty. Pointing both of these issues out to the customer resulted in a ground wire being provided that is grounded off a hard metal electrical conduit to a ground bar. I grounded the PBX and the Fax Finder to the ground bar that was provided and have had more fax failures (almost 25% of the total) and line noise complaints since it was installed that in the prior 9 months I have known them. The fax failures are on two existing fax servers that have been in place for quite a while so we have a history of their performance.
The carrier in this case is not a good one and has a really bad rep so maybe they were just having a bad day. Or I was running through all the changes that had been made in the last couple of days and realized the ground is new. If they are having difficulties again this AM I am going to go out and remove the wires and see if the failures subside. If so I am just going to have them buy a couple of those DiTek (?) boxes, which I have used before, and go from there.
My biggest failure is I don't have appropriate equipment to test for ground. We have evolved from a telephone install/programming shop to a little bit of everythig shop; thus the NEC refresher course. Back in the day when everyone had $$ we could just tell the customer to have their electrician provide a ground and get back to us... not quite so easy any more.
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1
- #6
While all installed conduit (even empty runs) are required to be grounded this is not a good way to get a ground for equipment protection. Notice that code does not allow the ground on an outlet to rely on the conduit body for ground, there must be a grounding conductor inside the conduit. That is because the conduit is not considered to be a good grounding conductor since one bad mechanical connection results in a high resistance ground path to every part beyond that point.
You need a good connection to the main electrical service ground located where the main electrical panel is located. The best way to do this is a separate run of wire to this point. The size depends on the distance and what you are grounding. In most cases I'm fairly sure you could use unprotected bare 4 AWG for this.
If for some reason you end up with another ground (like a 8' driven rod) it MUST be bonded to the electrical service ground.
The basic idea is a star topology of low resistance ground conductors all connected at the electrical service entrance.
You need a good connection to the main electrical service ground located where the main electrical panel is located. The best way to do this is a separate run of wire to this point. The size depends on the distance and what you are grounding. In most cases I'm fairly sure you could use unprotected bare 4 AWG for this.
If for some reason you end up with another ground (like a 8' driven rod) it MUST be bonded to the electrical service ground.
The basic idea is a star topology of low resistance ground conductors all connected at the electrical service entrance.
robertjo24
MIS
NEC states that you cannot use conduit as a ground.
Period
It is also just a bad idea, as the joints in conduit are not good electrical conductors.
If you are interested in the actual NEC article that spells this out, you can post your question on eng-tips.com in the IEEE (electrical) Code Issues thread (link below).
Period
It is also just a bad idea, as the joints in conduit are not good electrical conductors.
If you are interested in the actual NEC article that spells this out, you can post your question on eng-tips.com in the IEEE (electrical) Code Issues thread (link below).
- Thread starter
- #8
I wouldn't trust a water pipe as a ground source anymore. IMO
A lot of plastic pipe is used today and that can compromise a water pipe ground if plastic is used somewhere in the length of water pipe. I'm a retired Western Electric/Lucent installer and I've done a lot of grounding in telco offices and PBXs in the past. I'm not familiar with IT systems grounding, but I wouldn't think a water pipe would be proper.
Jim
A lot of plastic pipe is used today and that can compromise a water pipe ground if plastic is used somewhere in the length of water pipe. I'm a retired Western Electric/Lucent installer and I've done a lot of grounding in telco offices and PBXs in the past. I'm not familiar with IT systems grounding, but I wouldn't think a water pipe would be proper.
Jim
- Thread starter
- #10
OK - two things. My code class guy has informed me that according to the NEC conduit CAN be used as a ground IF all connections are wrench-tight. Since that is impossible to guarantee, most cities (or my new favorite term - Authorities Having Jurisdiction, or AHJ's) have written and exception into THEIR codes that says no can do because they are not in a position to guarantee a complete infrastructure is 'wrench tight.' And.. with regard to the water pipe.. it caused as many errors as being grounded to the conduit did so I just removed everything and now the equipment is working fine and I am going to make them order their DiTek boxes (or whatever they are called...have a couple coming from Graybar.) I didn't mention in my prior post that the equipment started having line noise failures at almost 25% with the grounds attached - both conduit and water pipe..which stopped as soon as I removed the ground wire. So I bet you are correct on the plastic pipe thing. I will remember that for future conversations. Plus we are going to start testing them ourselves.
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