Test Ques.

[don_resqcapt19]

...To that extent, I think that the 700A/in² is a conservative approach to cover all possible configurations and maybe a bit of a blunt instrument.

And while I am reasonably sure this is the answer any NEC test is looking for, it does not apply generally. It only applies to bus bars installed in an auxiliary gutter. The code does not specify the ampacity of bus bars used in any other application.

 

[Besoeker]

And while I am reasonably sure this is the answer any NEC test is looking for, it does not apply generally. It only applies to bus bars installed in an auxiliary gutter. The code does not specify the ampacity of bus bars used in any other application.

"auxiliary gutter"
I don't mean to be a pain but can you what that term means?

 

[K8MHZ]

"auxiliary gutter"
I don't mean to be a pain but can you what that term means?

A sheet metal or flame retardant non-metallic enclosure used to supplement wiring spaces. The enclosure has hinged or removable covers and is used for housing and protecting electrical wires, cable and busbars.

 

[texie]

I think we're going to have to get the Brit a copy of the NEC. I'm sure he would get a kick out of some of our terms and rules, just like we find some of their's amusing.

 

[don_resqcapt19]

"auxiliary gutter"
I don't mean to be a pain but can you what that term means?

I really don't know because I don't understand the difference between an auxiliary gutter and a wireway and why they have differing rules.

 

[texie]

I really don't know because I don't understand the difference between an auxiliary gutter and a wireway and why they have differing rules.

Gee, I'm glad it's not just me that has always found this to be a little confusing.

 

[K8MHZ]

I really don't know because I don't understand the difference between an auxiliary gutter and a wireway and why they have differing rules.

Hmmm.....

The way I see it a wireway is for wires and cable only. The aux gutter, 'used to supplement wiring spaces' can have busbar. Wireways have no limit on length, but aux gutters can only extend 30 feet beyond the equipment it serves.

Also, an aux gutter has to be supported every 5 feet, where you can go up to 10 for a wireway.

 

[don_resqcapt19]

Hmmm.....

The way I see it a wireway is for wires and cable only. The aux gutter, 'used to supplement wiring spaces' can have busbar. Wireways have no limit on length, but aux gutters can only extend 30 feet beyond the equipment it serves.

Also, an aux gutter has to be supported every 5 feet, where you can go up to 10 for a wireway.

Yes, but why? Physically there is no difference.

 

[K8MHZ]

Yes, but why? Physically there is no difference.

I'm just guessing, but the allowance for busbars may be the reason. The only 'construction' difference is about clearance from bare live conductors. 366.100(E)

 

[don_resqcapt19]

I'm just guessing, but the allowance for busbars may be the reason. The only 'construction' difference is about clearance from bare live conductors. 366.100(E)

I see the live part clearance as a sizing issue, not a "construction" issue.

 

[templdl]

Should bracing be a consideration also?

 

[K8MHZ]

I see the live part clearance as a sizing issue, not a "construction" issue.

I thought it was strange to see that under 'construction' myself. Especially when you see the requirement for the system to be complete before the conductors are installed.

 

[K8MHZ]

I am thinking that the real world application would be that if you use the 'duct' (for lack of a better word) to enclose a busbar, you have to follow the rules for 'auxiliary gutters'. If only wire is going to be used, you would be allowed to use the less restrictive rules for 'wireways'.

The only thing that muddies up my attempt at an explanation is the 'supplemental' part of the auxiliary gutter article.