what radius is chorus 900mm sweeping bend?

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dantheperson

174 posts

Master Geek

#247800 23-Feb-2019 20:37

Hi,

I'm doing some building work and have a trench open and our street is getting fibre in a few months.

I plan to get chorus in to lay their green cable. I've a couple of meters of trench to dig to get from the existing trench to the front corner where the fibre will come in.

This involves a 90 degree bend, which i understand should be a sweeping bend, but I'm having great difficulty figuring out the exact dimensions of this 900mm sweeping 90 degree bend so that I can dig an appropriate trench. Anyone know?

Thanks,
Dan.

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#2186071 23-Feb-2019 21:47

Any of these provide your answer?

https://corysadvantage.co.nz/products/browse/catfilter:4.80020859/Infrastructure/Conduit-Duct-Pits/Conduit-Accessories/Conduit-Special-Bends

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

djtOtago

1154 posts

Uber Geek

#2186086 23-Feb-2019 22:06

I would have thought a 900mm sweeping bend would have a radius of 900mm?

dantheperson

174 posts

Master Geek

#2186087 23-Feb-2019 22:30

Gordy7:

Any of these provide your answer?

https://corysadvantage.co.nz/products/browse/catfilter:4.80020859/Infrastructure/Conduit-Duct-Pits/Conduit-Accessories/Conduit-Special-Bends

I had a look there already but they have three bends, neither of which mention 900mm, so R530 perhaps.

BEND PVC GREEN CHORUS 20MM 90DEG R240 500MM.

BEND PVC GREEN CHORUS 20MM 90DEG R400 660MM.

BEND PVC GREEN CHORUS 20MM 90DEG R530 1000MM.

dantheperson

174 posts

Master Geek

#2186088 23-Feb-2019 22:31

djtOtago:

I would have thought a 900mm sweeping bend would have a radius of 900mm?

Or 900mm could be the length of the pipe?

Gordy7

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#2186089 23-Feb-2019 22:38

Make sure the street fibre ducts are going to meet up with your trench.

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

dantheperson

174 posts

Master Geek

#2186091 23-Feb-2019 22:47

Gordy7:

Make sure the street fibre ducts are going to meet up with your trench.

Yeah thanks, I did manage to get through to someone at chorus who could confirm where they planned to feed my property from.

Jase2985

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#2186142 24-Feb-2019 07:40

i don't think chorus will lay your conduit anymore, you will likely have to get it and lay it yourself (you may be able to get it from them though)

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Ruphus

465 posts

Ultimate Geek

#2186163 24-Feb-2019 09:33

A couple months ago, I put in a trench for fibre and grabbed some green telecoms conduit from Stewarts with a couple of 90deg sweeping bends. There was only one 90deg bend available and that was it.

I had to supply all materials, dig the trench from the boundary and get a contractor in to bore 3m under under a concrete path because Chrous's solution was unacceptable.

kiwifidget

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#2186165 24-Feb-2019 09:41

Isn't this just maths?

arc length = radius * central angle in radians

so radius = arc length / central angle in radians

Convert central angle to radians :

90 degrees = pi/2 = 1.5708

so radius will = arc length / 1.5708

900 / 1.5708 = 572.96

so close enough to 573mm

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djtOtago

1154 posts

Uber Geek

#2186219 24-Feb-2019 10:42

Yes, simple maths.

The real question is.
What does Chorus mean by "A 900mm sweeping bend"

A) A bend that has a radius of 900mm.

B) A 90 deg bend with a length of 900mm.

I vote the answer is A :)

Bung

6500 posts

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#2186226 24-Feb-2019 10:57

If the answer a A now go out and find a supplier that makes a 20mm 90 degree swept bend with a 900mm radius.
AFAIK there isn't one.

I realise that the usual Chorus diagram is not drawn to scale but it would be a very poor representation of a 900mm radius bend in a 450mm deep trench.

djtOtago

1154 posts

Uber Geek

#2186241 24-Feb-2019 11:33

Bung:

I realise that the usual Chorus diagram is not drawn to scale but it would be a very poor representation of a 900mm radius bend in a 450mm deep trench.

Thats a good point.

But a 900mm length 90 deg sweep has a radius of 573mm. That still wouldn't fit in a 450mm dep trench.

And I agree having a 900mm radius bend is big, and I don't recall ever seeing one.

But if any one said to me you need a "900mm 90 deg sweeping bend" my first thought would be it is a bend with a radius of 900mm.

Can @Chorus shed some light.

Bung

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#2186249 24-Feb-2019 11:49

The 450mm deep is a minimum and I'd expect having the bend stick up out of the ground slightly wouldn't be a problem. If you didn't look at the 900mm notation the drawing looks like a 300mm radius. Unless it's a bend done on site the spec should state the actual Iplex/Marley/etc bend that's needed.

raytaylor

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#2187136 25-Feb-2019 23:37

Here is what I give to electricians
We ask them to make sure some string or pull wire is installed before its buried, and we mandate a larger 32mm solid flexi duct because ideal electrical sell some nice large PVC bends

Ray Taylor

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chevrolux

4962 posts

Uber Geek
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#2187172 26-Feb-2019 07:51

Only stick formed bends at each end of the duct.

The 20mm duct is rather flexible and can be easily swept around 90 degree corners without the need for a formed bends.

Draw wire is good for a longer run (say 30m plus), otherwise it is just as easy for the boys to rod the duct over short distances.

Problems only come from ducts that have lots of formed bends in them. A continuous length swept around a corner doesnt make a problem.

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