Feeders, raceway, jam ratio.

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Steve@sei

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I just ran into an interesting issue with an engineer. There are requirements in a 140' run of 2-1/2" conduit with 4-4/0 XHHW to have a flexible connection at each end. From a J-box with distribution blocks we exit the bottom, 90 degree bend to a 45 degree offset and connect to sealtite with a straight connector. The engineer is directing us to install a sealtite 90 degree flex connection in the end of a 120' run of GRC.

At the other end of the run we are to make a connection from the end of the GRC with a straight sealtite connection and create a drip loop from the horizontal conduit run. This end will have about 270 degree of bend in the sealtite and will terminate in the bottom of another J-box with distribution blocks. \

So I sent the engineer information stating this installation is a code violation:

1. 300-18 Raceway systems must be installed complete prior to pulling conductors, noting the exection which does not apply in this case due to the sealtite 90 is in midspan of the raceway system and not at an end.
2. Chapter 9, 1 and 2 clearly indentify the radius of bends and offer jamming ratio for conductors.

The response I received back was that there is no code violation and you can put a sealtite 90 degree fitting midspan of a raceway system. I have also been told this engineer has the support of DOT engineers.

I have been in this industry for 35 years, I cannot imagine pulling these feeders through 495 degree of bends or trying to pull through a midspan sealtite 90. It goes without saying that I have not proceeded, but I have to ask. Has anyone else run into an issue of being directed to perform this type of installation? I now I'm getting a little set in my way of doing things. However is it allowed to install a seatite 90 mdispan of a feeder run? i my mind this would be the same as putting in a 90 degree plumbing ell. All of the work is exsposed.
 
IMO there should never be anything but a straight connector on the end of a pipe run. Maybe a 45 if there is no way around it. A 90 though, no way!!

I've only come across 90's on small runs with #12's, etc. Never anything big like 4/0, I hated it on the 12's, I won't even tell you what I think about 4/0:rant::rant: through one of those connectors midspan!

If you are over 360 degrees that's the article I'd use. I know of no code violation to use one midspan other than terrible work practice.
 
You cannot pull thru a 90? sealtite fitting in the middle of a run. I would add some j boxes esp since the code requires no more than 360? in any run without a box or conduit body.
 
I once worked for someone who thought if it could be drawn on a blackboard, it could be built.

Get his statements in writing, preferably in the form of an affidavit. He'll think twice before signing that document.

It's almost impossible to prove a negative, so I don't how much of what kind of evidence you'd need to get this requirement relieved.
It'll just seem like you don't want to do the work.
Maybe the parts makers can advise on what may work with their products, and what will definitely not work (and why).

Federal Dept. of Transportation engineers?
 
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I'm confused as you state in the first part that the sealtight is at each end of a run of 2?" GRC, but then at the end state that the 90? sealtight connectors are midspan?

If this seal tight is at the ends of a run of GRC then I see no problem as you stated it is exposed and thus removable as the 90? connectors are required to be exposed, how is this any different when we used to pipe to a motor then run a short length of sealtight from the pipe to the motor connection box?

As far as the requirement of no more then 360? of bends in a length of conduit, this is located in each article for each type of raceway it pertains to, so I see it as no more then 360? in the GRC then no more then 360? in each section of sealtight not the whole run, to me the conductors could be pulled into the GRC then installed into each section of sealtight, otherwise we would never be able to install 90? sealtight connection to motors or other type of uses.

But I agree this is a PITA if the run could be run all the way with GRC or only straight fittings on the sealtight, but I have seen both ways, and if this engineer is stubborn I don't really see away around it code wise?

remember there is a reason 350.42 states "Angle connectors
shall not be used for concealed raceway installations." this is so they can be taken apart and conductors installed or removed.
Also 350.26 states:
There shall not be
more than the equivalent of four quarter bends (360 degrees
total) between pull points, for example, conduit bodies and
boxes.
Click to expand...

being able to take the connection apart can be a pull point as it is done every day at motors.
Conduit bodies and box's are only examples of pull points.
 
hurk27 said:
I'm confused as you state in the first part that the sealtight is at each end of a run of 2?" GRC, but then at the end state that the 90? sealtight connectors are midspan?
Click to expand...

I think he was saying the engineer responded that a 90 sealtite conn can be installed mid span. I think in actuality it is at the end.
 
I guess citing 300.18 could be an argument, but if the intent is as it states then using any flexible raceway with a 90? fitting at the end of a conduit or EMT run would never be allowed as you would not ever be able to install the conductors before the flexible conduit was attached to the box, so why do they make EMT to flex str or 90?s,

300.18 does state "Prewired
raceway assemblies shall be permitted only where specifically
permitted in this Code for the applicable wiring
method."

Is pipe to flex an applicable wiring
method? if not there are a whole lot of violations out there.
 
Thanks for all of the interest

Thanks for all of the interest

The engineer DOES show the 90 in mid span. Execptions do allow you to install a sealtite or flex 90 at the end of a run for connection to utilization equipment, that is not the case here. Taking a run of raceway apart in order to install conductors is not the intent or safe practices of the NEC, in my opinon. Regardless of the nearly 500 degrees of bend. Chapter 9 gives us all the radius of raceways for safe installation of conductors in a raceway system. It also includes jam ratio calculations. So taken as a whole I believe the code does not allow for a sealtite 90 to be installed mid span, because 300-18 states the raceway system must be complete... exception noted. The main reason the code restricts installing 90 flex connectors in walls is because you cannot pull through them without risk to the conductors. The thing that really bugs me is he states that he has had this done before and does not understand what my problem is.

I will never refuse to follow instructions, do my job or finish a contract. I will always refuse to knowingly install equipment that is in violation of the NEC and NFPA.
 
Steve@sei said:
I will never refuse to follow instructions, do my job or finish a contract. I will always refuse to knowingly install equipment that is in violation of the NEC and NFPA.
Click to expand...
Your only ally may be the AHJ.

If you can't get the local planning department to reject the plans, can you sell the engineers on a gradual sweep, rather than a 90 deg. connector?
 
I'm not sure I totally follow the explanation of the layout and it's requirements but it appears from the OP's standpoint it is unacceptable but from other's viewpoint it is doable.I would set down over coffee or something stronger with the engineer and come up with an acceptable compliant design that everyone is happy with,,,,,,,,,hey Christmas is coming,everyone should give a little.

I once told an engineer one time if you listen more and crack the whip less we will both get a raise and you will be hero.

dick
 
The solution to the issue is this, a 90 degree sealtite connector is not a coupling, therefore not intended to be used as one. Chapter 9 tables on bending radius for various raceway sizes is clear for wire protection and therefore having the sealtite 90 anywhere but the end for connecting to utilization equipment is not allowed by 300-18.
 
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