Minimum Bend Radius

[ATSman]

Can anyone tell me what the minimum bend radius of 750 MCM THHN low voltage cable ?

Thanks!

Tony

 

[chris kennedy]

Are you talking about inside enclosures? See T312.6(A) and (B).

 

[iwire]

Can anyone tell me what the minimum bend radius of 750 MCM THHN low voltage cable ?

I don't think there is one in the NEC for 600 volt conductors.

It has been pointed out that the manufacturers may have recommendations and that may bring 110.3(B) up.

 

[ohmhead]

Well if its copper its how strong you are .

Or use a greenlee wire bender.

If its alu well it easy to get a tight radius .

Just a little fun !:grin:

But someone told me many years ago min is 5 to 6 times the diameter of any conductor but do not take this as a true fact this is just a field kinda thing .

 

[chris kennedy]

I don't think there is one in the NEC for 600 volt conductors.

It has been pointed out that the manufacturers may have recommendations and that may bring 110.3(B) up.

I'm sorry but I believe both the above statements need further clarification.

 

[76nemo]

I'm sorry but I believe both the above statements need further clarification.

On 600V wiring applications?

 

[chris kennedy]

On 600V wiring applications?

What isn't an install of 600V conductors?

BTW, nice to see you here.

 

[76nemo]

What isn't an install of 600V conductors?

BTW, nice to see you here.

Been busy, busy on control work for now.

 

[76nemo]

Been busy, busy on control work for now.

110.3 (3) is somewhat new to me as it stands.

 

[ohmhead]

Well heres a switchgear switchboard

The switchgear in this picture is the larger types of switchgear or boards youll see .


And here a distribution panel

SORRY I POSTED THIS IN THE WRONG ONE !
On the wall you see two smaller cans thats kinda what youll have or smaller there 800 /1000 amp panels in this generator room .

 

[Cow]

What isn't an install of 600V conductors?

Something higher, like MV.

 

[iwire]

I'm sorry but I believe both the above statements need further clarification.

The NEC has minimum conductor bending radius for conductors above 600 volt.

II. Requirements for over 600 Volts, Nominal

300.34 Conductor Bending Radius. The conductor shall
not be bent to a radius less than 8 times the overall diameter
for nonshielded conductors or 12 times the overall diameter
for shielded or lead-covered conductors during or after installation.
For multiconductor or multiplexed singleconductor
cables having individually shielded conductors,
the minimum bending radius is 12 times the diameter of the
individually shielded conductors or 7 times the overall diameter,
whichever is greater.

I do not know of any similar requirement for conductors under 600 volt.

 

[a.bisnath]

old rule

old rule

never go under 6 times diameter for bend,special bending jigs are made,got that from an old english engineer
"the internal radius of every bend in a cable shall be not less than 6 times the overall diameter of the cable but shall be increased to 10 times when lead or aluminium sheath or varnished-cambric cables are used."
he got it from the IEE regulations

 

[iwire]

never go under 6 times diameter for bend,special bending jigs are made,got that from an old english engineer
"the internal radius of every bend in a cable shall be not less than 6 times the overall diameter of the cable but shall be increased to 10 times when lead or aluminium sheath or varnished-cambric cables are used."
he got it from the IEE regulations

That is about cables, I think the OP is asking about single conductors.

 

[Mike01]

750's wow

750's wow

Wow 750's are huge I do not know how the contractors bend some of this stuff sometimes I once got to assist on some 500's and thought that was a pain... what is the largest cable avaliable out there??? Just curious what everyone has come across, I personally try not to spec. over 600's sometimes not even thoes if I can help it...Parralel conductors are my firends......

 

[weressl]

Can anyone tell me what the minimum bend radius of 750 MCM THHN low voltage cable ?

Thanks!

Tony

Manufacturer's installation instructions are the guiding documents here. I do not know if it is part of the listing/testing process or not.

Here is an example from Okonite:

http://www.okonite.com/engineering/bending-ratios.html

It is for both single and multiconductor cables.

I have a question though: if the manufacturer's instruction differs from the NEC 'requirements' which one would/should you follow?

 

[K8MHZ]

Wow 750's are huge I do not know how the contractors bend some of this stuff sometimes I once got to assist on some 500's and thought that was a pain... what is the largest cable avaliable out there??? Just curious what everyone has come across, I personally try not to spec. over 600's sometimes not even thoes if I can help it...Parralel conductors are my firends......

I ran the big stuff for a couple months. We used hydraulic wire benders. For the tight bends we were using the bender was absolutely necessary.

Here is the one we used:

http://www.toolup.com/greenlee/800.html

 

[Rockyd]

Wow 750's are huge I do not know how the contractors bend some of this stuff sometimes I once got to assist on some 500's and thought that was a pain... what is the largest cable avaliable out there??? Just curious what everyone has come across, I personally try not to spec. over 600's sometimes not even thoes if I can help it...Parralel conductors are my firends......

Haven't been on one of those wind farms yet?

Did a couple of wind turbines on Kodiak and we ran parallel 777 DLO cables. Talk about a bear to handle - DLO has a soft rubber outter jacket...


500's are not bad, and fit in 4" pipe, 777's in a 5" pipe, are not something you handle, they handle you!

 

[drbond24]

Can anyone tell me what the minimum bend radius of 750 MCM THHN low voltage cable ?

Thanks!

Tony

At worked for a wire manufacturer for a couple of years. Here is the chart we always sent out as a recommendation:

 

[weressl]

At worked for a wire manufacturer for a couple of years. Here is the chart we always sent out as a recommendation:

No to be a fickle about it, but it is always proper to include the source of such materials for two reasons;

1. Copyright
2. Identifying the responsible party, so it can be judged by the installer the authority of such statements.

As you can see the data here differs from the Okonite data I've supplied in an earlier post. Were you to use this data in installing an Okonite cable, you were to relieve Okonite of any consequentual liability.