500 MCM cable bend

[waelatallah]

Hi,

I have a couple of 500MCM cables passing in a 5inch conduit. the contractor installed a pull box and did two 90 degree bends to continue the run.


blue is the conduit. Red is the pull box.

Would he be able to pull the 500MCMs through this pull box. Is there a rule of thumb to approximate the bends allowed? would'nt it be better if he can make a 45 degree bend without the use of a pull box?

Thanks,

 

[augie47]

Wouldn't second guess the contractor as what's "best". The concept meets the NEC and may have been necessary to avoid having more than 360? of bends in the run.

 

[K8MHZ]

Wouldn't second guess the contractor as what's "best". The concept meets the NEC and may have been necessary to avoid having more than 360? of bends in the run.

Do they use the NEC in Canada?

 

[kwired]

Hi,

I have a couple of 500MCM cables passing in a 5inch conduit. the contractor installed a pull box and did two 90 degree bends to continue the run.

View attachment 9195
blue is the conduit. Red is the pull box.

Would he be able to pull the 500MCMs through this pull box. Is there a rule of thumb to approximate the bends allowed? would'nt it be better if he can make a 45 degree bend without the use of a pull box?

Thanks,

What is between what you have drawn and the final destinations of the conduit?

As Augie said, if there are more bends he may have needed a pull box to comply with codes.

 

[kingpb]

As long as the radius of each bend is at least 12-15 times the overall OD of a single cable, then probably OK.

If you want to put the issue to rest, simply ask for the pulling tension and side wall pressure calc for the pull. A qualified contractor would need to have done this so shouldn't be an issue for him to provide a copy of the calc's.

 

[petersonra]

Hi,

I have a couple of 500MCM cables passing in a 5inch conduit. the contractor installed a pull box and did two 90 degree bends to continue the run.

two 500 kcm in a 5" conduit?

you ought to be able to pull that fairly easily.

 

[kwired]

two 500 kcm in a 5" conduit?

you ought to be able to pull that fairly easily.

easy and 500kcm don't really belong in same sentence, but all things considered, only two in a 5" conduit is probably going to be fairly easy compared to most cases where 500 is used.

 

[infinity]

1 meter = 39.37"
Straight pull 8X the raceway size: 8 * 5" = 40"
Pull box is too small.

 

[steve66]

1 meter = 39.37"
Straight pull 8X the raceway size: 8 * 5" = 40"
Pull box is too small.

No offense, but I'm really glad you're not an inspector

 

[infinity]

No offense, but I'm really glad you're not an inspector

 

[kingpb]

For consistency, you should not mix and match your units. if the conduit is truly 5", then the metric designator is 129mm.

8 x 129mm = 1032 mm which means the 1m (1000mm) pull box is short by 32mm

Using inches the 8 x 5in = 40 inches but that converted to metric is 1016mm which means you are 16mm short if it is truly a 1-m box.

So, the question is, is it a 40" tall box or a 1-m box, because one works the other does not.

Hence, don't mix units!

 

[kwired]

For consistency, you should not mix and match your units. if the conduit is truly 5", then the metric designator is 129mm.

8 x 129mm = 1032 mm which means the 1m (1000mm) pull box is short by 32mm

Using inches the 8 x 5in = 40 inches but that converted to metric is 1016mm which means you are 16mm short if it is truly a 1-m box.

So, the question is, is it a 40" tall box or a 1-m box, because one works the other does not.

Hence, don't mix units!

Or don't round off the conversion

Also if the box is 40" tall (outside dimension) inside will be reduced by the wall thickness times two.

 

[steve66]

Or don't round off the conversion

Also if the box is 40" tall (outside dimension) inside will be reduced by the wall thickness times two.

I think the pull box is fine. I wouldn't have an issue with it being a fraction of an inch too small - I think its close enough.

But if you have an inspector that likes to split hairs, and if the conduits enter the box offset from each other (either front to back or side to side) by at least 8", then we have more than 40" total distance between the two conduit entries, and it meets code without a doubt.

Or another way to make it comply would be to use a 4" chase nipple was used at the box entries, then we only need a 36" tall box (8x4" = 36"). After all, he did say it was only a couple of 500 KCM wires. Even 4 would work in a 4" conduit.

Again, I'm not seriously suggesting the contractor do either of these - I think the pull box close enough to 40".