10 wires in a conduit

[earlejohnson]

Heard a new one today looked and can't find it someone told me today that by code you are not allowed to put any more than ten wires in any size conduit. As always thanks for your help.

 

[infinity]

Unless it's a local code, the person who told you that has no idea what they're talking about.

 

[augie47]

It's a common-place-ole-wives-tale based on the fact that your 10th current carrying conductor requires a 50% derating which can be the killer on a circuit utilizing #12 or #14. Often times rather than providing an explanation of de-rating, electricians are told "no more than 10 wires".

 

[qcroanoke]

It's a common-place-ole-wives-tale based on the fact that your 10th current carrying conductor requires a 50% derating which can be the killer on a circuit utilizing #12 or #14. Often times rather than providing an explanation of de-rating, electricians are told "no more than 10 wires".

Just the 10th conductor or all of 'em?
Seriously,We stop at 9 for that reason.

 

[kwired]

Table 310.15(B)(3)(a) Adjustment Factors for More ThanThree Current-Carrying Conductors in a Raceway or CableNumber ofConductors​

Percent of Values inTable 310.15(B)(16) throughTable 310.15(B)(19) asAdjusted for Ambient​

Temperature if Necessary

4–6 807–9 7010–20 5021–30 4531–40 4041 and above 35​

Number of conductors is the total number of conductors in the raceway​

or cable adjusted in accordance with 310.15(B)(5) and (6).

Table format did not copy very well.

I wanted to point out that if no more than ten conductors was the rule why would this table go beyond 10 conductors?

Show that to whoever informed you this information and see what they have to say.


Wow, the format was not that good when composing - got even worse after submitting the reply.

 

[Dennis Alwon]

I wanted to point out that if no more than ten conductors was the rule why would this table go beyond 10 conductors?.

Good point :thumbsup:

 

[acrwc10]

Heard a new one today looked and can't find it someone told me today that by code you are not allowed to put any more than ten wires in any size conduit. As always thanks for your help.

You know whatever they is going to be wrong when they say "Wires" and not conductors.

 

[jumper]

You know whatever they is going to be wrong when they say "Wires" and not conductors.

Or " The code says"....I usually stop them there and ask "Which code and what article/section".

 

[petersonra]

As a practical matter for CCC, it is not far off.

 

[K8MHZ]

I know a school that has 108 #8's in a 3 inch run of RMC. State inspector approved it. I was a second year apprentice when we did the pull. Ripped tandem tuggers off guard rail, breaking the logging chain holding it there. The meter on the lead tugger read 2900 lbs. just before the break.

 

[kwired]

I know a school that has 108 #8's in a 3 inch run of RMC. State inspector approved it. I was a second year apprentice when we did the pull. Ripped tandem tuggers off guard rail, breaking the logging chain holding it there. The meter on the lead tugger read 2900 lbs. just before the break.

Assuming THHN/THWN you should need at least 3-1/2 inch RMC to be under 40% fill.

Ampacity of those conductors should be 19.25 amps - must be 15 amp circuits, or could be motors with full load of 15.4 amps or less and still have higher than 15 amp overcurrent devices - like say 36 10hp 480 volt 3phase motors could be supplied with this number and size of conductors.