CKT WIRE COUNT

[Alwayslearningelec]

If you had a homerun with (10) 1pole 20A circuits and the spec did not say isolated ground, separate neutral etc. would your wire counts be the following: (10) hots and (3) neutrals and use the conduit for the ground? These would be feeding receptacles or lighting not motors.

If there were isolated grounds speced for each circuit you would have (10) additional isolated ground wires??

Thanks

 

[stickboy1375]

If you had a homerun with (10) 1pole 20A circuits and the spec did not say isolated ground, separate neutral etc. would your wire counts be the following: (10) hots and (3) neutrals and use the conduit for the ground? These would be feeding receptacles or lighting not motors.

If there were isolated grounds speced for each circuit you would have (10) additional isolated ground wires??

Thanks

10 hots and 3 neutrals?

 

[Alwayslearningelec]

10 hots and 3 neutrals?

Can't 3 circuits share a neutral,,,but if so then that is only 9 hots....???

 

[Smart $]

Can't 3 circuits share a neutral,,,but if so then that is only 9 hots....???

10 hots, no less than 4 neutrals.

...and yes that would be 10 IG's by most person's reckoning. However, in most cases, circuits spec'd as IG are also spec'd with dedicated neutral.

 

[Alwayslearningelec]

10 hots, no less than 4 neutrals.

...and yes that would be 10 IG's by most person's reckoning. However, in most cases, circuits spec'd as IG are also spec'd with dedicated neutral.

Thanks a lot Smart. Can you explain what the neutral count is based on....thanks.

 

[Smart $]

Thanks a lot Smart. Can you explain what the neutral count is based on....thanks.

Well, you said 10 "circuits". On a 3? wye system (e.g. 208/120V 3? 4W), the max is 3 hots to each neutral. You could also have 2 hots share a neutral. Obviously you can also have a two-wire circuit with one hot and one neutral. Therefore for 9 circuits the minimum number of neutrals is 3. Adding the 10th hot requires the 4th neutral.

 

[hillbilly1]

Thanks a lot Smart. Can you explain what the neutral count is based on....thanks.

The 10 circuits? You reference 10 circuits with 3 neutrals, then say 3 circuits per neutral, unless it's government math, that equals 4 neutrals.

 

[Little Bill]

Thanks a lot Smart. Can you explain what the neutral count is based on....thanks.

Well, you said 10 "circuits". On a 3? wye system (e.g. 208/120V 3? 4W), the max is 3 hots to each neutral. You could also have 2 hots share a neutral. Obviously you can also have a two-wire circuit with one hot and one neutral. Therefore for 9 circuits the minimum number of neutrals is 3. Adding the 10th hot requires the 4th neutral.

I may be wrong, but I think he was asking about the neutral count when IG are speced. You had mentioned that sometimes specs call for dedicated neutral.

 

[Smart $]

I may be wrong, but I think he was asking about the neutral count when IG are speced. You had mentioned that sometimes specs call for dedicated neutral.

Well, he didn't specify in that particular post

If dedicated neutrals are spec'd, there'd be 10 hots, 10 neutrals, 10 IG's, and 1 EGC (whether conduit or wire, or both).

 

[cdslotz]

Well, he didn't specify in that particular post

If dedicated neutrals are spec'd, there'd be 10 hots, 10 neutrals, 10 IG's, and 1 EGC (whether conduit or wire, or both).

Don't forget to derate now that the iso-neutrals are now current carrying conductors

 

[infinity]

Could there be an any bigger waste of money than pulling 10- IG's for 10 circuits? :roll:

 

[iwire]

Could there be an any bigger waste of money than pulling 10- IG's for 10 circuits? :roll:

Well, we had an engineer spec a 750 copper from the service in a basement up 5 floors to a audio / video rack. I felt a bit odd nut and bolting that size lug onto the sheet metal of the rack. :roll:

 

[hbiss]

If you understand isolated ground each IG receptacle shouldn't share anything. Dedicated hot and neutral to each IG receptacle and the IG conductor goes back to the service entrance, not a sub panel.

Fortunately IG circuits are rarely needed today and are a waste of money.

-Hal

 

[cdslotz]

Fortunately IG circuits are rarely needed today and are a waste of money.

-Hal

Like the 200% neutral/K-13 scare of the late 90's

 

[Smart $]

If you understand isolated ground each IG receptacle shouldn't share anything. Dedicated hot and neutral to each IG receptacle and the IG conductor goes back to the service entrance, not a sub panel.

Debatable.

With dedicated circuit neutrals, the current combines at the panel neutral bus. A shared circuit neutral would simply extend some of the combining to a remote junction.

Also, many believe a feeder IG conductor to isolated grounding bus in the subpanel was (is?) sufficient. There is no NEC requirement here either way.

Fortunately IG circuits are rarely needed today and are a waste of money.

Takes the fun out of debating the issue

 

[kwired]

Well, we had an engineer spec a 750 copper from the service in a basement up 5 floors to a audio / video rack. I felt a bit odd nut and bolting that size lug onto the sheet metal of the rack. :roll:

And maybe on top of that you did not even have 750 copper service conductors run to the building right?

If you understand isolated ground each IG receptacle shouldn't share anything. Dedicated hot and neutral to each IG receptacle and the IG conductor goes back to the service entrance, not a sub panel.

Fortunately IG circuits are rarely needed today and are a waste of money.

-Hal

Then they messed up any IG there was by connecting communication cables with grounded shield to other equipment on other IG circuits, and wanted to solve any issues they were having by driving ground rods:roll:

 

[Fulthrotl]

Could there be an any bigger waste of money than pulling 10- IG's for 10 circuits? :roll:

how about a 1 1/4" EMT conduit all the way to the data closet, for every.single.cat 6. in a building?

 

[infinity]

Could there be an any bigger waste of money than pulling 10- IG's for 10 circuits? :roll:

how about a 1 1/4" EMT conduit all the way to the data closet, for every.single.cat 6. in a building?

There certainly is more than one.

 

[iwire]

And maybe on top of that you did not even have 750 copper service conductors run to the building right?

Well it was a 3000 amp service, I think 8 sets of 500 or 600 Kcmils.

But our foreman on the job talked the EE into letting us cadweld the 750 to building steel right near the rack so we did not have to drop down 5 floors with it.

 

[Stevareno]

If you understand isolated ground each IG receptacle shouldn't share anything. Dedicated hot and neutral to each IG receptacle and the IG conductor goes back to the service entrance, not a sub panel.

Fortunately IG circuits are rarely needed today and are a waste of money.

-Hal

IG <> dedicated circuit.
My understanding of IG is that only the ground is required to be dedicated.
Back when IG was "the thing to do", the IGs were separated from other circuits but they weren't required to be dedicated.

If that is not the case, then I know of many places where they did it wrong.