[Iwattmore]

On site now: have a 20A 120V single phase dedicated circuit with 10AWG conductors. Off that are 2 12A nameplate rated pieces of equipment connected with 12AWG flexible cord drops.

They are tripping the breaker would it be 2008 NEC compliant to increase the ampacity to 30A?

 

[Dennis Alwon]

On site now: have a 20A 120V single phase dedicated circuit with 10AWG conductors. Off that are 2 12A nameplate rated pieces of equipment connected with 12AWG flexible cord drops.

They are tripping the breaker would it be 2008 NEC compliant to increase the ampacity to 30A?

I would think not but it may depend on the nameplate & the type of equipment

 

[Big John]

What's the equipment? What's the current draw? Why is the breaker tripping?

 

[Dennis Alwon]

What's the equipment? What's the current draw? Why is the breaker tripping?

2- 12A units on a 20 amp breaker

 

[Meadow]

If these a hard wired then I guess tap rules would apply, however if connected via a NEMA 5-15 you can not put a 15 or 20 amp on the circuit even if they just feed the equipment.

 

[Iwattmore]

They are a table top heat sealer for shrink wrapping. 115V 12A nameplate rated per machine. 2 machines connected to the 10AWG feed connected to two 12AWG flexible cords in the junction box. 10AWG on a 20A breaker.

 

[99cents]

What's the equipment? What's the current draw? Why is the breaker tripping?

There's your magic question.

 

[Meadow]

They are a table top heat sealer for shrink wrapping. 115V 12A nameplate rated per machine. 2 machines connected to the 10AWG feed connected to two 12AWG flexible cords in the junction box. 10AWG on a 20A breaker.

Any disconnects to them? If there was a fused disconnect for each one I would bump up to 30 in a heart beat.

 

[Meadow]

There's your magic question.

12+12=24 on a 20 amp.

 

[Speedy Petey]

Any disconnects to them? If there was a fused disconnect for each one I would bump up to 30 in a heart beat.

Agree.

If they are plug in with 15 or 20A plugs/receptacles/caps you definitely CANNOT do it.
This is why all the details are important. Just saying you have two #12 drops is not enough.

 

[Meadow]

This might help:

http://www.mikeholt.com/mojonewsarchive/NEC-HTML/HTML/FeederSecondaryTapRules~20020326.htm

 

[99cents]

They are a table top heat sealer for shrink wrapping. 115V 12A nameplate rated per machine. 2 machines connected to the 10AWG feed connected to two 12AWG flexible cords in the junction box. 10AWG on a 20A breaker.

You have two 12A machines connected to a single 20A circuit? Now I understand why it's tripping. Carry on, gentlemen...

 

[macmikeman]

Branch circuit turned into feeders for a new sub panel with two new 20 amp circuit breakers controlling the two loads attached to the panel. Ace hardware sells those two circuit nema 1 loadcenters. This may not sit perfectly with code but imho the more overcurrent protection the merryier in the case of machinery.

 

[Iwattmore]

Exactly my thought 24 amps of potential current tripping the breaker. Funny thing it's been ok since they put it in over a year ago.

Only disconnect is the breaker at the panel. What code section is being used for using disconnects for the two drops ?

 

[Speedy Petey]

A 20A circuit will carry 24A for quite a while.

 

[Dennis Alwon]

A 20A circuit will carry 24A for quite a while.

If these machine are running all the time it will trip eventually.

I would add a fused disconnect for each unit and then use the 30 amp feeder as someone suggested. Otherwise the #12 on the circuit will not allow a 30 amp overcurrent protective device

 

[Meadow]

Branch circuit turned into feeders for a new sub panel with two new 20 amp circuit breakers controlling the two loads attached to the panel. Ace hardware sells those two circuit nema 1 loadcenters. This may not sit perfectly with code but imho the more overcurrent protection the merryier in the case of machinery.

Code would actually recommended that over anything else.

Exactly my thought 24 amps of potential current tripping the breaker. Funny thing it's been ok since they put it in over a year ago.

Only disconnect is the breaker at the panel. What code section is being used for using disconnects for the two drops ?

Don't reuse the breaker, good chance its ruined from repeated overheating, tripping and resetting.

I don't know about the NEC but if those machines are in an industrial facility they should have a disconnect within sight
to satisfy safety requirements. If not a red push button with a shunt trip feeder breaker...

To keep it simple drop a 2 space QO panel from HD and call it good:

http://www.homedepot.com/p/Square-D...L30SCP/100157760?N=bm0u?Ns=P_REP_PRC_MODE%7C0#

 

[99cents]

Exactly my thought 24 amps of potential current tripping the breaker. Funny thing it's been ok since they put it in over a year ago.

Only disconnect is the breaker at the panel. What code section is being used for using disconnects for the two drops ?

Your breaker could be getting tired and trip time can decrease after multiple trips.

 

[Iwattmore]

Yes breakers a are designed to carry current rates above the marking on the breaker. I have seen a 20A carry 21A continuous but of course not NEC compliant.

Looking at the wiring here it seems like the best course of action will be pulling another conductor here from the panel for accessibility reasons. Got no where to mount a disconnect except where the drop is off the ceiling 16ft overhead.

 

[Meadow]

Your breaker could be getting tired and trip time can decrease after multiple trips.

Yup. The UL trip curves actually say a breaker can hold 24 amps forever or at a minimum for several hours. But after a while the breaker does get warn down.