Conduit Support at Junction Box

[LAWaterInspector]

Full disclosure - I'm a water inspector not an electrician or electrical inspector. I have a project where we have several concrete water tanks with electrical junction boxes/pull boxes mounted on the sides. We have rigid metal conduit that transitions from underground duct banks and is routed to these electrical junction boxes as shown in the image below. The conduit is not supported within 3 feet of the junction box as required by NEC 344.30 and it has been identified as a deficiency by the engineer. The contractor has indicated the supports are not required because the conduit is supported by the ground where it is directly buried, but I can't find anything in the code to support this position. We also have this issue throughout the site with conduit bodies and other small fittings where we don't have supports within 3 feet.

Questions:

1. From a code perspective, why are supports required within 3 feet of junction boxes, conduit bodies, etc.?
2. Is there any exception for the application shown below where the conduit transitions from below grade to a termination at the box?
3. What are the implications if we don't enforce the code requirement? Could the installation fail over time?

Thanks in advance for your feedback.

<iframe src="https://watersystemsconsulting-my.sharepoint.com/personal/jpickard_wsc-inc_com/_layouts/15/embed.aspx?UniqueId=5f17fab4-3a67-4881-b1cc-2f33a494ee19" width="640" height="360" frameborder="0" scrolling="no" allowfullscreen title="Conduit at Junction Box.png"></iframe>

 

[infinity]

Your link didn't work. Can you click in the image icon and upload it directly?

 

[LAWaterInspector]

It doesn't look like I'm able to upload a photo as new user. Hopefully after another post or two.

 

[LAWaterInspector]

Here's my sketch. Any help would be appreciated.

 

[dkidd]

344.30 Securing and Supporting. RMC shall be installed
as a complete system in accordance with 300.18 and shall
be securely fastened in place and supported in accordance
with 344.30(A) and (B).

What you describe does not meet this requirement.

 

[LAWaterInspector]

344.30 Securing and Supporting. RMC shall be installed
as a complete system in accordance with 300.18 and shall
be securely fastened in place and supported in accordance
with 344.30(A) and (B).

What you describe does not meet this requirement.

Thanks for the response. What is the underlying concern that forms the basis for this code requirement? What happens if the supports don't get installed?

 

[Rick 0920]

Thanks for the response. What is the underlying concern that forms the basis for this code requirement? What happens if the supports don't get installed?

Rigid Metal Conduit is pretty stout. I do not know why the CMP's came up with the 3' securing rule. It could have just as easily have been 2' or 4'! The fact of the matter is that it is a requirement per the NEC to secure and support conduits within 3' of the box unless the structural members don't readily permit securing within 3'. Then it is allowed to be increased to 5'. That doesn't seem to be the case here. Your question of what happens if the supports don't get installed, well that depends on all the conditions present. IMO, unless they are subjected to severe physical damage, there will probably be zero adverse effects by not securing them. My question is, why wouldn't you just want the contractor to install a short piece of strut fastened to the concrete structure and use strut straps to secure the conduits as required by the NEC?

 

[infinity]

Thanks for the response. What is the underlying concern that forms the basis for this code requirement? What happens if the supports don't get installed?

What happens? Probably nothing because RMC is very strong and the 3' dimension is pretty arbitrary. Is there a reason why it cannot be supported as required by the NEC?

 

[augie47]

I have seen rigid conduits pull loose from J boxes due to poor backfill practice. In this case, supporting as required by Code might be a preventative measure for that eventuality.

 

[LAWaterInspector]

Thanks all for the feedback. I neglected to mention that there are two rows of conduit, which makes access more difficult to install strut behind and get support clamps on the back row.

 

[tom baker]

With some fussing the strut and straps on the back row can be installed

 

[Rick 0920]

Thanks all for the feedback. I neglected to mention that there are two rows of conduit, which makes access more difficult to install strut behind and get support clamps on the back row.

If you don't have enough room between conduit rows to install the strut straps on the back row, there is really nothing much you can do to make this NEC compliant without reworking the conduits. You're at the mercy of the AHJ at that point. It is not compliant to secure conduit from other conduit, but a solution might be to strap the front row with strut and straps, then use back-to-back Minerallac straps to secure conduit to conduit. Maybe your inspector will allow this and give you a slap on the wrist and tell you to plan better next time. I personally don't think there will be any problems if you don't strap them at all, but it's still not NEC compliant.

 

[tom baker]

What if a concrete pad was poured around the conduits, extend 12” each way.

 

[Rick 0920]

What if a concrete pad was poured around the conduits, extend 12” each way.

I like that! Still not compliant but lets the AHJ know that you are doing everything you can to make it better.

 

[augie47]

I like that! Still not compliant but lets the AHJ know that you are doing everything you can to make it better.

If the pad reduces the length of the exposed conduit to less than 3' I would see that as Code compliant.

 

[infinity]

If the pad reduces the length of the exposed conduit to less than 3' I would see that as Code compliant.

I agree, not much is stronger than poured concrete to support a raceway.

 

[Strathead]

Huh? Are people here actually making an argument that I have to support a conduit that extends less than three feet from the ground to a securely mounted junction box on a wall?

 

[infinity]

Huh? Are people here actually making an argument that I have to support a conduit that extends less than three feet from the ground to a securely mounted junction box on a wall?

The conduits in question are 5' long into the box.

 

[Rick 0920]

If the pad reduces the length of the exposed conduit to less than 3' I would see that as Code compliant.

LOL...true However the OP said they were 5' from the box. That's a lot of concrete!

 

[Rick 0920]

Huh? Are people here actually making an argument that I have to support a conduit that extends less than three feet from the ground to a securely mounted junction box on a wall?

I don't think "argument" is necessarily correct. I think we are stating NEC articles and sections that state it does not comply. A lot of code sections do not carry a lot of weight in the common sense areas.