piggy-back breakers in 120 volt panel

[winslowfam]

Hi...I am looking into what the NEC says about the use of piggy-back single pole breakers in a 120/240 volt single phase panel. The only restriction I have seen so far is the limit of 42 poles per panelboard. I was wondering if anyone can point me to a code entry that limits or restricts the number of or use of these type of breakers other than what I have found so far.
Thanks.

 

[bphgravity]

Re: piggy-back breakers in 120 volt panel

Beyond the code requirement installation standard of the max 42 overcurrent devices, you have product standards. The panelboard will be designed for a maximum number of tandem devices and the tandem devices will be listed or classified for use in certain panelboards. All this will have to be verified.

 

[winslowfam]

Re: piggy-back breakers in 120 volt panel

Thank you. I have heard from an electrician that very thing that certain panelboards will physically only allow a certain number of piggy-back breakers and that they usually only allow them in the top portion of the panelboard. I had heard a complaint that these type of breakers cannot be locked out, that the manufacturers have not developed a device to lock them out individually...but most of the loads on this panelboard are within site of the panel. This allows them to be non-lockable as long as they are within sight of what they feed.

 

[al hildenbrand]

Re: piggy-back breakers in 120 volt panel

While there are elements of your question that relate to the NEC, I think you are asking a question that, for a complete answer, must include specific manufacturer instructions for the exact equipment you are asking about. The manufacturer's catalogs (many are available online) and customer service will be the source of whether a lockout accessory exists for the particular tandem breaker.

Workplace safety standards in effect for the facility the tandem breaker is located in will apply.

Tandem breakers are idiosyncratic, and hard to generalize about. Make and model specifics will be required.

Even the location on a bus bar that they can be mounted is inconsistent.

 

[winslowfam]

Re: piggy-back breakers in 120 volt panel

Thanks again...I will pursue that.

 

[charlie b]

Re: piggy-back breakers in 120 volt panel

Originally posted by winslowfam: I have heard . . . that certain panelboards will physically only allow a certain number of piggy-back breakers . . . .

It's not just a matter of whether they will physically fit. If the manufacturer does not tell you (in product literature or otherwise) that they are allowed to be put into their panel, then you can't do it, even if they do fit.

Originally posted by winslowfam: I had heard a complaint that these type of breakers cannot be locked out. . . .

There aren't all that many loads that require their branch circuit breakers to be lockable. What is the application, and why do you think the breakers must be lockable?

 

[jeff43222]

Re: piggy-back breakers in 120 volt panel

I believe the NEC requires lockable breakers for hardwired appliances under certain circumstances. An inspector once emphasized this to me during a rough-in inspection.

[ December 29, 2005, 03:42 PM: Message edited by: jeff43222 ]

 

[don_resqcapt19]

Re: piggy-back breakers in 120 volt panel

While the code rules may not require the ability to lock out the branch breakers the LOTO rules do, if you are working on the circuit or the equipment served by those branch breakers. Also there is at least one brand of piggy back breakers that have lock out devices available.
Don

 

[charlie b]

Re: piggy-back breakers in 120 volt panel

Originally posted by jeff43222: I believe the NEC requires lockable breakers for hardwired appliances under certain circumstances.

I recognize that. My point is that the NEC does not require you to hard-wire any appliances. The owner can always buy appliances that have a plug & cord option.

 

[hurk27]

Re: piggy-back breakers in 120 volt panel

winslowfam

There are a couple things that you must know when using tandem breakers, The NEC only allows type CTL tandem breakers to be installed in "CTL" type panels. This will be in all new installations. In exsisting panels you can use type "NC" for replacement of existing tandems only! You should never use type "NC" in a newer panel.

Here is a couple UL web pages about panelboards and breakers:

UL's Marking guide to panelboards

UL's Marking guid to molded case breakers

And here's a code corner's question to this:
UL Question Corner

 

[don_resqcapt19]

Re: piggy-back breakers in 120 volt panel

Wayne,

The NEC only allows type CTL tandem breakers to be installed in "CTL" type panels.

In this area, that is the only type of tandem breaker that you can buy from the supply houses or big box stores without a special order.
Don

 

[electricman2]

Re: piggy-back breakers in 120 volt panel

Not long ago saw some tandem breakers at Home Depot. Marked "for replacement only, not to be used in non-CTL equipment". Logic dictates someone used these in non-CTL panels to gain an extra space.

 

[jeff43222]

Re: piggy-back breakers in 120 volt panel

Originally posted by charlie b:

Originally posted by jeff43222: I believe the NEC requires lockable breakers for hardwired appliances under certain circumstances.

I recognize that. My point is that the NEC does not require you to hard-wire any appliances. The owner can always buy appliances that have a plug & cord option.

I agree that the NEC doesn't require hardwired appliances, and I push the cord-n-plug option every chance I get. But sometimes I get stuck dealing with HOs who have already bought the appliance that can't be cord-n-plugged, and they have no interest in swapping.

Under those circumstances, the NEC requires me to install a breaker lock.

 

[macmikeman]

Re: piggy-back breakers in 120 volt panel

I concur that I have seen "NC" breakers for sale at Home Depot. My eyes rolled up so bad in my head I needed assistance to leave the store. Kidding.

 

[allenwayne]

Re: piggy-back breakers in 120 volt panel

I guess other than SQ D QO`s unless you are dealing with an pushmatic (Who remembers those )A standard lock out would fit all tandems.You might have to lock out both but it would work.I checked schnieders sqd site and saw no piggy back lock outs only retainers for 1 and 2 poles.Strange that they can make a breaker that is listed but can`t be locked out.Did someone at UL have a moment

 

[allenwayne]

Re: piggy-back breakers in 120 volt panel

Meant to say retainers and lock outs for 1 and 2 pole breakers

 

[don_resqcapt19]

Re: piggy-back breakers in 120 volt panel

I checked schnieders sqd site and saw no piggy back lock outs

They have them and each side has its own lockout. I don't have the part number handy, but I have some of them at work...won't be back there until next year.
Don

 

[jim dungar]

Re: piggy-back breakers in 120 volt panel

Square D #QO1PAF - "For padlocking single-pole side-by-side QOT breaker in the "ON" or "OFF" position"

Digest 173 page 6-12

 

[allenwayne]

Re: piggy-back breakers in 120 volt panel

OK what about a piggy back breaker they have 2 handles one above another.I wasn`t talking about side by side tandems.

 

[jim dungar]

Re: piggy-back breakers in 120 volt panel

Allen what is the catalog number of the breaker you are talking about? Are you looking at one of the very old (read obsolete) Square D front to back tandem breakers?

Breaker padlock attachements are accessories. Accessories are optional. Neither UL, tne NEC, nor any other entity that I know of requires breakers to be capable of being padlocked. Every reference to padlocking, that I am aware of, is only when a seperate disconnect is not provided.