tandem breaker question

[hhsting]

Tandem breakers can they be used on commercial space? I have panelboard that has branch circuits feeding space like Kumon learning center. Does NEC 2017 allow tandem breakers in panelboards or not? Tandem breakers are 2-20A breaker in one space and their are 6 of them in 30 space panelboard

 

[roger]

If the breaker(s) and panel are listed for it yes, 110.3(b).

Roger

 

[synchro]

There are some jurisdictions where tandem breakers are not allowed.
For example, in 240.85 of the Chicago Electrical Code:

 

[roger]

There are some jurisdictions where tandem breakers are not allowed.
For example, in 240.85 of the Chicago Electrical Code:

View attachment 2558566

True, but this thread is in the NEC forum.

Roger

 

[synchro]

As of 2018 the Chicago Electrical Code is based off of the 2017 NEC and it duplicates it verbatum probably more the 95%, but it has ammendments. Before that it had its own language.

https://catalog.nfpa.org/NFPA-70-National-Electrical-Code-with-Chicago-Amendments-P18112.aspx

 

[roger]

As of 2018 the Chicago Electrical Code is based off of the 2017 NEC and it duplicates it verbatum probably more the 95%, but it has ammendments. Before that it had its own language.

https://catalog.nfpa.org/NFPA-70-National-Electrical-Code-with-Chicago-Amendments-P18112.aspx

Good for Chicago although I don't think it will help the OP in Glen bunie.

So do they allow NM now.

Roger

 

[synchro]

Good for Chicago although I don't think it will help the OP in Glen bunie.

So do they allow NM now.

Roger

NM is only allowed for temporary wiring and extensions to knob-and-tube.
But they carry it in the big box stores here, and so I suspect it's being used for more than just that.

 

[electrofelon]

There are some jurisdictions where tandem breakers are not allowed.
For example, in 240.85 of the Chicago Electrical Code:

View attachment 2558566

What on earth is the rationale for that??

 

[synchro]

There are some jurisdictions where tandem breakers are not allowed.
For example, in 240.85 of the Chicago Electrical Code:

View attachment 2558566

What on earth is the rationale for that??

Increases the number of required panel replacements and therefore the permit fee revenue?

 

[Another C10]

What I find to be amazing is lets say typically each fin can independently withstand 60 amps of current if the main permits .. so removing that in Chicago to install lets say 2-20 amp tandems is unlawful .. who makes these rules ..

 

[don_resqcapt19]

As of 2018 the Chicago Electrical Code is based off of the 2017 NEC and it duplicates it verbatum probably more the 95%, but it has ammendments. Before that it had its own language.

https://catalog.nfpa.org/NFPA-70-National-Electrical-Code-with-Chicago-Amendments-P18112.aspx

Per the adopting ordinance the use of tandem breakers is still prohibited in the 2018 Chicago Electrical Code.

The provisions of Article 240 of NFPA 70 are adopted by reference with the following modification:
1. Insert the following language at the end of section 240.85 and before informational note:
“Circuit breakers and their enclosures shall be of such design that it will be impossible to substitute two or more circuit breakers in a space previously occupied by a lesser number of circuit breakers. Tandem circuit breakers shall not be permitted to be used as overcurrent devices.”

 

[tthh]

Chicago code is definitely stricter, and in some cases, too strict. But, the OP ran across a panel that is full and already has 6 tandems in it -- that may not be a violation, but it also just doesn't seem right to me.

 

[don_resqcapt19]

Chicago code is definitely stricter, and in some cases, too strict. But, the OP ran across a panel that is full and already has 6 tandems in it -- that may not be a violation, but it also just doesn't seem right to me.

Other than a local code, you look to the manufacturer's instructions for the maximum permitted number of overcurrent devices. Some panels are marked for the use tandems in all breaker spaces, some in just a few of the breaker spaces, and others the number of breaker spaces equals the number of permitted breakers...no tandems.