Confusion abounds over the use of bike ambit breakers in panelboards, alike amid electricians and electrical inspectors. Today I’ll set the almanac beeline as to back bike ambit breakers can be used. This is an adjustment of an commodity I wrote for the ASHI Reporter, which was appear in February of 2011.
First, a quick definition. A bike ambit breaker is a bifold ambit breaker that takes up the amplitude of a distinct ambit breaker on a panelboard. You’ll additionally apprehend them alleged duplex, slimline, twin, half-height, half-inch, bifold and dent breakers, depending on bounded customs. While a two-pole ambit breaker gets affiliated to two adapted poles at a panelboard and has a accepted cruise or a handle tie for accompanying disconnecting of two poles, a bike breaker does not.
The photo beneath shows a 60 amp two-pole ambit breaker at the top, again a 15 amp bike ambit breaker (highlighted), again a 20 amp bike ambit breaker (highlighted), again a 20 amp single-pole ambit breaker at the bottom.
The aing photo shows an earlier appearance bike breaker begin in Square D panelboards.
Because bike ambit breakers acquiesce for two circuits to be installed on a panelboard in a one ambit breaker space, they’re about acclimated afterwards a panelboard has been abounding to accommodation with accepted ambit breakers. Because of this, they’re generally referred to as “cheaters.”
Is this absolutely ‘cheating’? No, it’s not. The use of bike ambit breakers is a altogether adequate practice, as continued as the panelboard is advised for bike ambit breakers and they’re installed in locations aural the panelboard area they’re allowed.
How does a home ambassador actuate whether bike ambit breakers are accustomed on the panelboard they’re inspecting? There are a cardinal of agency to do so.
Class CTL Panelboards
Panelboards charge chase UL Accepted 67, which requires all lighting and apparatus panelboards to be Chic CTL (Circuit Absolute Limiting). Here’s an old blueprint for free how abounding circuits are accustomed in the Chic CTL panelboard actuality inspected; this blueprint is accessible to use back analytical earlier electric panels afterwards bright labeling central the panel. Take the amperage of the panelboard, accumulate by the cardinal of poles, and bisect by 10. It sounds complicated, but it’s not — let’s use a 100-amp panelboard as an example:
Based on this formula, the best cardinal of circuits accustomed in a 100-amp 120/240-volt panelboard is 20. For panelboards not bogus as “lighting & appliance” panelboards, there is no absolute to the cardinal of ambit breakers allowed. This blueprint is additionally no best applicative for today’s panels.
The 2008 National Electrical Code (NEC) makes it a little confusing. Previous editions of the NEC bound the best cardinal of circuits in a lighting and apparatus panelboard to 42. The 2008 adaptation of the NEC removed the “lighting & appliance” panelboard designation, however, NEC 408.54 says “A panelboard shall be provided with concrete agency to anticipate the accession of added overcurrent accessories than that cardinal for which the panelboard was designed, rated, and listed.”
Manufacturers still account the best cardinal of ambit breakers allowed, and charge accommodate a bounce affection to advice anticipate the use of bike ambit breakers area not allowed.
Class CTL panelboards acquire adapted methods of preventing chic CTL bike ambit breakers from actuality acclimated in locations area they’re not allowed. This is referred to as a “rejection feature”. In the photo below, the accent bus stabs are alveolate to acquiesce the use of bike ambit breakers; the bus stabs which don’t acquire this cleft won’t acquiesce bike breakers.
Class CTL bike ambit breakers acquire a adapted appearance than accepted distinct pole ambit breakers, to advice anticipate them from actuality installed area they don’t belong.
Tandem ambit breakers are bogus this way in an accomplishment to anticipate bodies from application them in an abnormal address – but this doesn’t stop everyone. In the photos below, you can see how addition bankrupt the cheers of the ambit breakers to accomplish them fit area they didn’t belong. This is apparently area the appellation “cheater” comes from.
For panelboards bogus afore acceptance of the Chic CTL standard, non-Class CTL bike ambit breakers are accustomed to be installed as backup ambit breakers only. Non-Class CTL bike ambit breakers do not acquire the ‘rejection’ affection that Chic CTL breakers have. As acutely adumbrated by the characterization on the ancillary of the ambit breaker pictured below, these ambit breakers are not accustomed in ClassCTLpanelboards. The adversity for home inspectors is that the appearance is not usually arresting afterwards installation, and home inspectors aren’t declared to cull out ambit breakers to try to amount this being out.
Now that I’ve talked about the accepted rules for bike ambit breakers, I’ll altercate the agency that home inspectors or electrical inspectors can actuate back bike ambit breakers are accustomed in assorted panelboards.
The archetypal or allotment cardinal of the electric panelboard usually will announce whether or not the electric panelboard is advised to acquire bike breakers and how abounding can be used. Here are a few examples:
I anticipate it’s accessible abundant to see the pattern.
The base diagram central the panelboard is a abundant way to actuate if bike breakers are accustomed and, if so, exactly where they’re allowed. In the photo below, you can see that the top four spaces acquiesce alone abounding admeasurement breakers, while the basal eight slots acquiesce bike breakers.
Here’s addition panelboard diagram – this panelboard allows the use of bike breakers in four locations.
And addition – this panelboard doesn’t allow any tandem breakers.
And addition – this panelboard allows bike breakers in the basal ten spaces alone (11-20 and 31-40).
Another accessible affair to attending for is a characterization advertence the maximum cardinal of circuits allowed. In the photo below, you can see that alone 20 circuits are accustomed at the panelboard. This panelboard has 20 full-size spaces, so bike ambit breakers aren’t allowed.
When bike ambit breakers are acclimated in locations area they’re not allowed, they could accomplish an abnormal concrete affiliation to the bus bar in the panelboard, which can actualize a blaze hazard. Bike ambit breakers additionally access the absolute amount on the bus confined in a panelboard; this is area home inspectors charge to use accepted sense.
When a home ambassador finds bike ambit breakers acclimated in abnormal locations, they’ll generally acclaim adjustment by an electrician. If the bus confined of the panelboard acquire been damaged or adapted to acquiesce for the accession of bike ambit breakers, the able adjustment is to acquire the panelboard replaced. There is no way for a home ambassador to actuate if the bus confined acquire been damaged afterwards absolutely removing the ambit breakers, which is commodity home inspectors shouldn’t be doing.
Information for this commodity was provided, in part, by Alan Manche of Schneider Electric, Stephen Ploszay of Siemens Industry, Inc. and Joseph Fello of Eaton Corporation. Also, a appropriate acknowledgment to Retired ASHI Member Douglas Hansen.
Reuben Saltzman, Structure Tech Home Inspections – Email – Minneapolis Home Inspector
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