• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

Using conduit as ground

M

mshields

Silver Member
Joined
Aug 9, 2011
Messages
105
Location
Plymouth, MA
Is it still permissible to use conduit (i.e. IMC or RSC) as the ground. And if so, can I safely assume that it is not permissible to use EMT?

Thanks,

Mike
 
250.118 Types of Equipment Grounding Conductors.

The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a

combination of the following:

FPN: For effective ground-fault current path, see 250.2 Definition.

(1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered,

or bare; and in the form of a wire or a busbar of any shape.

(2) Rigid metal conduit.

(3) Intermediate metal conduit.

(4) Electrical metallic tubing.

(5) Listed flexible metal conduit meeting all the following conditions:

a. The conduit is terminated in listed fittings.

b. The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.

c. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible

metal conduit in the same ground return path does not exceed 1.8 m (6 ft).

d. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.

(6) Listed liquidtight flexible metal conduit meeting all the following conditions:

a. The conduit is terminated in listed fittings.

b. For metric designators 12 through 16 (trade sizes 3/8 through ½), the circuit conductors contained inthe conduit

are protected by overcurrent devices rated at 20 amperes or less.

c. For metric designators 21 through 35 (trade sizes ¾ through 1¼), the circuit conductors contained in

the conduit are protected by overcurrent devices rated not more than 60 amperes and there is no

flexible metal conduit, flexible metallic tubing, or liquidtight flexible metal conduit in trade sizes

metric designators 12 through 16 (trade sizes 3/8 through ½) in the grounding path.

d. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the

same ground return path does not exceed 1.8 m (6 ft).

e. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.

(7) Flexible metallic tubing where the tubing is terminated in listed fittings and meeting the following conditions:

a. The circuit conductors contained in the tubing are protected by overcurrent devices rated at 20 amperes or less.

b. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible

metal conduit in the same ground return path does not exceed 1.8 m (6 ft).

(8) Armor of Type AC cable as provided in 320.108.

(9) The copper sheath of mineral-insulated, metal-sheathed cable.

(10) Type MC cable where listed and identified for grounding in accordance with the following:

a. The combined metallic sheath and grounding conductor of interlocked metal tape–type MC cable

b. The metallic sheath or the combined metallic sheath and grounding conductors of the smooth or corrugated tube-type MC cable

(11) Cable trays as permitted in 392.3 and 392.7.

(12) Cablebus framework as permitted in 370.3.

(13) Other listed electrically continuous metal raceways and listed auxiliary gutters.
 
Last edited by a moderator:
You can also find the info in each article of the corresponding conduits. For instance EMT is in 358.60. RMC 344.60, and IMC 342.60. Notice that they are all in the xxx.60 sections
 
Greetings,

I'm hearing of locales doing away with unthreaded conduit for a ground which I think is a great idea. We require ground conductor in all conduits where I'm at now.

BSSTG
 
BSSTG said:
Greetings,I'm hearing of locales doing away with unthreaded conduit for a ground which I think is a great idea. We require ground conductor in all conduits where I'm at now.

BSSTG
Click to expand...
Is that an amendment or just the inspectors requirements?
 
BSSTG said:
Amendment. I never require anything that's not in writing. BSSTG
Click to expand...
I am curious. When you have an amendment, who is responsible for it being passed into code. Town Council??
 
I am curious. When you have an amendment, who is responsible for it being passed into code. Town Council??
Click to expand...
Somewhere in the process, it's supposed to get recorded in to the official minutes of

the AHJ regular meeting, whenever that is, usually by the AHJ Clerk. It then becomes

an officially recorded document of that AHJ.

.
 
globe trekker said:
Somewhere in the process, it's supposed to get recorded in to the official minutes ofthe AHJ regular meeting, whenever that is, usually by the AHJ Clerk. It then becomes

an officially recorded document of that AHJ..
Click to expand...
I thought it had to be officially adopted by the town not just written up by the AHJ. A state amendments needs okay by the building code council before it can be adopted but not sure about local amendments. I thought it had to be more than an ahj meeting. Are you talking state amendment or local?
 
gfretwell said:
If the workmanship is up to par, there is nothing wrong with using a raceway as a grounding conductor.
Click to expand...
Disagree completely. It's not that the piping install is incorrect. It's building movement and long time maintenance. I see it just about everytime I go to an older school with covered awnings over sidewalks. Conduit run underneath pulling apart cause the awning is in poor condition.

BSSTG
 
Dennis said:
I am curious. When you have an amendment, who is responsible for it being passed into code. Town Council??
Click to expand...
City Council. It's in the codification process. We have several amendments to the adopted building codes. It's common in So. Tx.

BSSTG
 
Yeah IF what???????

What if I don't make a good splice in a wire type equipment grounding conductor?

Workmanship is an issue whether we use EMT as an EGC or a wire type EGC.

Chris
 
No grounding method is bullet-proof. The vast majority of failures are due to poor installation, not some inherent defect in the method.
 
no. If they use a wire type EGC, I require it to be sized correctly.. and it never is.
 
You must log in or register to reply here.
Top