Bending Radius for uPVC 6" Cable Conduits

Should be in here somewhere...

https://napcopipe.com/sites/default/files/media/EL-BR-022-CA-EN-0319.1_Rigid-PVC-Pipe-Fittings.pdf

much obliged for the gracious guidance, if i can request for uPVC rather than Rigid PVC, this would be wonderful please.

I think upvc is called rigid pvc....

https://www.hunker.com/12363307/the-differences-between-upvc-pvc-pipes

Are you using uPVC which here in Australia means drain pipe?

Is it allowable to use uPVC instead of electrical orange conduit in your country for buried in ground cable entries?

I have found for 150mm conduit it is far simpler to use preformed bends rather than try to make a bend in the conduit for it always wants to collapse unless it is over a form or packed with sand and heated and still the end result is no pleasing and if using a bending spring you will have a tough time trying to remove it.

There are preformed bends for uPVC which will make your job easier.

There are many companies that make benders for all varieties of PVC conduit and pipe.

Some use compressed air to maintain the internal diameter while bending and cooling.

5X the diameter of the conduit is a safe rule-of-thumb number to work with.

It is less for small conduit,but in the 6 inch diameter, 5X is pretty close.

Remember,the sharper the bend,the harder it is to pull wire through the conduit.

When pulling around multiple turns,these friction points really add up.

The maximum number of 90 degree bends is 4,If there are no other offsets or bends in the pipe.

Even 1 minor offset reduces the number to 3.

Total degrees of all angles,including offsets cannot exceed 360 degrees.

The pre-made Elbows come in both a standard,and long Ell version.

I always select the long Ell if possible.

These are cheaper for small jobs,but large jobs may justify buying a bender and training users.

Do not buy a cheap bender if you decide to buy one.

Do your home work,read reviews,and exercise due diligence when making your purchase.

The above dimension are referenced to the NEC handbook,used in most USA states.

International standards may differ.

Your local inspector or AHJ is your best point of contact on these matters.

Good luck.

May i request your opinion as to why there is difference between TIA and NEC in Rigid PVC conduit bending radius [90 degree], as per guideline from TIA it seems it asks for 10 times the internal diameter whereas lets say for 6 inch size for NEC for Rigid PVC it requires 762 and 914.4mm.

is there any standard which is as same as NEC for the conduit bend (rigid PVC) from the following:

ITU-T

IEEE

IEC

BICSI

ETSI

NEMA

EIA

TIA

SEC (Security Directives for Industrial Facilities )

Well there might be a difference in the cable type...for a large heavy cable the bend would not likely be the minimum...The best thing is to acquire copies of all the relevant codes you will be dealing with, and read them all for the various applications you are using...There might also be variations for lubricated cable and non-lubricated pulls, temperature range, ground type, elevated or buried etc etc....

I am only familiar with the NEC,but it would seem,in my opinion,the other codes favor a smoother bend to reduce pulling stress on the conductors and minimize deforming of the internal diameter of the bend.

When pulling certain signal wires,and fiber,NO bends are allowed.

Turns must be made within a junction box only and the dimensions of these boxes are specified to give adequate room for safe low stress turns.

Where are you located? Local codes can also differ from national codes.

ALWAYS check with the AHJ!

Can anyone advise if there is any guideline about Rigid PVC (UPVC) radius in BS EN 1401-1? Just want to compare the difference with NEC.

Our Project has currently selected 6 inch PVC-U conduit (internal dia 150mm) which has 12 sub-conduits (1inch each, external dia 31mm). So the fear is that the bending radius as per NEC would not be enough. The FOC might get damaged.

FOC Datasheets are as following:

I don't think you will find a universally accepted standard that is accepted by everyone.

That is because everyone has their opinion.

And you know what they say about opinions.

The ones that should matter to YOU,are the ones in the local area where you intend to do the work,and the cable manufacturers specification as it applies to bend radius,etc.

Put on your thinking cap,dig deep into the specifications,and derive an answer that fits your needs.

You have not told us where you are located or provided any other information that was requested.

You have been advised several times to consult with the AHJ,so that is my final answer in that regard.

I cannot help nor respect someone that will not help themselves.

Gentlemen,

For those who are asking me to do local analysis and where is the project from etc etc, kindly note as following:

The project is a port project in Saudi Arabia and has some standards in current specification which flowed in from FEED. The standards are:

ITU-T

IEEE

IEC

BICSI

ETSI

NEMA

EIA

TIA

SEC (Security Directives for Industrial Facilities )

The only local code applicable here shall be SBC (Saudi Building Code) if any, that is not much helpful and the Client is advising to select one of the above standard.

I have shared the selected FOC Datasheet, i have also shared that detailed query that Our Project has currently selected 6 inch PVC-U conduit (internal dia 150mm) which has 12 sub-conduits (1inch each, external dia 31mm). So the fear is that the bending radius as per NEC would not be enough. The FOC might get damaged.

Due to design time / construction schedule issue, we do not want to change the 914mm radius of these conduits (90 degrees) which have already been selected and modeled, however we do not want a scenario where the FOC might get damaged as well.

so to sum up, will NEC bending radius be enough? is there any NEMA/TIA or any standard requested above allows the same bending radius for 6" UPVC conduit since NEMA/TIA as compared to NEC are on higher side (1.22-1.55).

Is there some reason why this information cannot be had from the <...conduit...> supplier using the telephone?

We have approached the conduit suppliers but the reply i feel is bit shaky, vendor is mentioning Radius as per NEMA TC9 EB for 150mm conduit size, however i cannot find these radius in NEMA TC9:

The reply from supplier is as following:

1. Since the size specified in your project is 150MM it is better to opt NEMA standards as there is no specific standard for this particular size in European-International standards unless the Drainage specification is used and I believe later on there will be confusion with standards.
2. Accordingly, we recommend to use Size 6”/150MM DUCT PIPES manufactured according to NEMA TC8 EB-35 with minimum Modulus of Elasticity of 500,000 Psi. (35 stands for the stiffness of Pipes - 35 PSI)
3. With regard to BENDS, we do have facility to fabricate BENDS from DUCTS with minimum Radius of 24”(610MM) to any RADIUS….30” (760MM), 36” (916MM) and so on. Larger Radius like 3 Mtr and above (mostly used in Communication Duct Banks) shall be fabricated in Segments.
4. Regarding PEC DUCTS, since your required size in 150MM we cannot propose the same in PECD; currently we do produce PECD with built-in subducts of 110MM OD.

There is a difference between the <...bending radius...> and the bend radius, which may be where some confusion lays.

• The <...bending radius...> is that which is introduced by the Installer, by deforming the material out of straight, at site.
• The bend radius is that produced by off-the shelf curved parts that fit the straight parts as part of the manufacturer's product range.

Both may be obtained by discussion with the manufacturer. A telephone discussion should sort it out.

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https://www.acronymfinder.com/FOC.html

Here is a good reference for your questions that compare EIS with NEC for conduit bend radius.

Everything you wanted to know but were reluctant to ask.

https://www.lanshack.com/DesigningConduitRuns.aspx#

Much obliged! This is a fantastic article and wonderful insight. Can I request, if you have it, any knowledge of an online calculator for Pulling Tension Calculation for the FOC? Our client wants this calculation to ensure FOC will survive during construction.

It's a bit overkill. The final testing, that of verifying are all signal paths operating correctly, ought to be sufficient.

Sounds like there is a Client with both a Gantt Chart and too much time on their hands...

The maximum allowable pulling tension on fiber cable can vary and is dependent on the cable construction. The maximum tension for a particular cable can be found on the cable spec sheet.

Here is a link to calculate pulling tension:https://www.econline.com/doc/calculating-cable-pulling-tensions-0001

Here is a guide for installing FO cable that may be useful:

https://www.thefoa.org/tech/ref/install/installcbl.html

Lots of information and guidance,caveats,etc.here

Good luck.(But remember, luck tends to favor the prepared mind)

Link.

The bend radius of the outer 6" (150mm) conduit may not be of primary interest. Instead, the bend radius of the internal 1" (25mm) conduits will matter more.

Even with the minimum 24" radius (4D) bends for the 6" conduit, this will be 24D for the 1" conduits. This may be well more than ample.

Other things come into play as well, such as total degrees of bend in a run, total length of run, and orientation of parts of a run. For instance, a vertical run will have very little sidewall friction.

Excellent point for the 1" conduit. Is there any software or calculation sheet for FOC where this can be checked?

https://cr4.globalspec.com/thread/135753/NEMA-Standard-for-Rigid-PVC-U-PVC-Conduit-Bending-Radius