Does sleeve have to be bonded?

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Steelhead

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Hi guys,
I have to run an equipment bonding jumper from the frame of a machine to building steel. I want to sleeve the bonding jumper with a short (less than 5 feet) piece of EMT. Does the EMT have to be bonded? Could I get a code reference? The feed to the machine is all properly grounded and bonded to the EGC. This bonding I want to do is in addition to what was originally installed.

Thanks
 
For this application bonding is not required.

250.86 Other Conductor Enclosures and Raceways. Ex-
cept as permitted by 250.112(I), metal enclosures and race-
ways for other than service conductors shall be connected
to the equipment grounding conductor.
Exception No. 1: Metal enclosures and raceways for con-
ductors added to existing installations of open wire, knob-
and-tube wiring, and nonmetallic-sheathed cable shall not
be required to be connected to the equipment grounding
conductor where these enclosures or wiring methods com-
ply with (1) through (4) as follows:
(1) Do not provide an equipment ground
(2) Are in runs of less than 7.5 m (25 ft)
(3) Are free from probable contact with ground, grounded
metal, metal lath, or other conductive material
(4) Are guarded against contact by persons
Exception No. 2: Short sections of metal enclosures or
raceways used to provide support or protection of cable
assemblies from physical damage shall not be required to
be connected to the equipment grounding conductor.
Click to expand...
 
First since the conductor in question has no real function it doesn't really matter what you do with it.

Second, if you intend (it should never be carrying any amount of current unless there is something seriously wrong with the electrical system) for this conductor to be able to carry any amount of current, you would have to bond both ends of the sleeve to prevent the choke effect...just like what is required for a Grounding Electrode Conductor.
 
Steelhead said:
Exception 2 states cable assemblies. Does a 1 AWG THHN copper conductor qualify?
Click to expand...

Sorry I misread the application. Since this is for a single conductor not a cable assembly you can disregard the specific information in post #2. :ashamed1:
 
Steelhead said:
Hi guys,
I have to run an equipment bonding jumper from the frame of a machine to building steel. I want to sleeve the bonding jumper with a short (less than 5 feet) piece of EMT. Does the EMT have to be bonded? Could I get a code reference? The feed to the machine is all properly grounded and bonded to the EGC. This bonding I want to do is in addition to what was originally installed.

Thanks
Click to expand...
You may have a problem separate from the general raceway provision in 250.86, if the EMT is ferrous metal. If you use aluminum EMT, not problem.

Take a look at the provisions of 300.20 and also 250.64(E) for Grounding Electrode Conductors (GECs). The latter does not apply to EGCs, but it is not clear to me from your description how your wire would be classified. 250.64 applies to "enclosures" which, unlike "raceways" also includes sleeves for pure mechanical protection.

As a practical matter, any benefits you expect to get from adding the conductor to building steel may be negated at least in part by the choke effect if you do not bond to that sleeve. Bond ferrous EMT, use aluminum EMT or use a plastic sleeve for mechanical protection only. Your choice.
 
GoldDigger said:
You may have a problem separate from the general raceway provision in 250.86, if the EMT is ferrous metal. If you use aluminum EMT, not problem.

Take a look at the provisions of 300.20 and also 250.64(E) for Grounding Electrode Conductors (GECs). The latter does not apply to EGCs, but it is not clear to me from your description how your wire would be classified. 250.64 applies to "enclosures" which, unlike "raceways" also includes sleeves for pure mechanical protection.

As a practical matter, any benefits you expect to get from adding the conductor to building steel may be negated at least in part by the choke effect if you do not bond to that sleeve. Bond ferrous EMT, use aluminum EMT or use a plastic sleeve for mechanical protection only. Your choice.
Click to expand...

The additional bonding is at the recommendation of a PLC power quality specialist. This machine may be having problems associated with a power quality issue. The additional bonding is to hopefully correct or reduce erratic machine behavior. I used a piece of 3/4 EMT to run a 1 AWG THHN Copper conductor thru. The EMT is for protection.The EMT is ferrous. One end of conductor is connected to the machine frame and the other end is connected to building steel. I'm not expecting any current to be flowing thru this conductor but.... the posssbity exists I suppose. Are you saying that both ends of the sleeve should be bonded to the additional bonding conductor that I just installed? Should I also use the same size conductor? The OCP for this machine is 600A fuses. (I couldn't use the lay in lug for a 3/4" bonding bushing because it wasn't big enough for the 1 AWG conductor so I installed a larger lug on the bushing)
 
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Steelhead said:
GoldDigger said:
As a practical matter, any benefits you expect to get from adding the conductor to building steel may be negated at least in part by the choke effect if you do not bond to that sleeve. Bond ferrous EMT, use aluminum EMT or use a plastic sleeve for mechanical protection only. Your choice.
Click to expand...

The additional bonding is at the recommendation of a PLC power quality specialist. This machine may be having problems associated with a power quality issue. The additional bonding is to hopefully correct or reduce erratic machine behavior. I used a piece of 3/4 EMT to run a 1 AWG THHN Copper conductor thru. The EMT is for protection.The EMT is ferrous. One end of conductor is connected to the machine frame and the other end is connected to building steel. I'm not expecting any current to be flowing thru this conductor but.... the posssbity exists I suppose. Are you saying that both ends of the sleeve should be bonded to the additional bonding conductor that I just installed? Should I also use the same size conductor? The OCP for this machine is 600A fuses. (I couldn't use the lay in lug for a 3/4" bonding bushing because it wasn't big enough for the 1 AWG conductor so I installed a larger lug on the bushing)
Click to expand...

If the specialist is looking for a high quality ground that will reduce high frequency deviations, surges, electronic noise, etc. then you should either avoid using ferrous EMT, avoid using a sleeve altogether, or if you must use EMT do something (not necessarily up to code requirements) to bond the sleeve to the conductor at both ends. Or just use a run of conduit with no conductor in it instead of a conductor in a ferrous sleeve.

If the concern is line frequency voltage offset issues rather than high frequency components, then the sleeve will not make a big difference.
But I suspect that your specialist is concerned with high frequency transients and noise on the machine ground.
 
Steelhead said:
The additional bonding is at the recommendation of a PLC power quality specialist. This machine may be having problems associated with a power quality issue. The additional bonding is to hopefully correct or reduce erratic machine behavior. ...
Click to expand...
If the existing service and electrical system is correctly installed, it is very unlikely that the installation of this additional bonding connection will do anything other cost the customer a bit more money.
 
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