House Doc
New member
- Location
- Stuart, FL USA
I have a dryer rated 120/240 26a. That is more than the 5000 watts as per code. Homeowner says that it trips 30 amp breaker after running for at least 5 minutes. Any thoughts or solutions?
Dryers
- Thread starter House Doc
- Start date
- Status
Does it trip the cb on the tumble(no heat) setting? If it only trips on heat, and you have checked your cb , its probably the dryer.
Last edited:
growler
Senior Member
- Location
- Atlanta,GA
I had a service call for that same problem about a month ago. I put an ammeter on the circuit at the panel after checking all connection and it took about 30 minutes for the breaker to trip the first time and then on a couple of minutes after that. I was reading around 24 amp current draw.
I expected that the breaker would heat up but that didn't happen. I installed a new 30 amp breaker and called after they had done all of their backed-up laundry and it still hadn't tripped.
It can be the dryer or the receptacle or arcing and heating at the breaker. Or it can be just a bad breaker.
A 30 amp breaker wll normally hold a bit more than 30 amps for 5 minutes so you should see a higher current draw at some point.
Another thing I would add would be to check to see if that circuit is really dedicated- many times that 30 for the dryer "feeds" something else that is unseen.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
26 amps seems a little high, but I don't really know what some of the more modern dryers are rated at. 30 amp breaker can certainly hold for some time at 30 amps and even above. Once dryer is warmed up it will cycle the heat element so it is not like it will draw 26 amps for the entire cycle, but could for first 5-10 minutes.
check breaker terminals and bus connections, poor connection in either area will likely lead to tripping. If bus connection has been overheated don't use that space it will never work well again - also replace breaker or it will likely just burn out another bus connection.
check breaker terminals and bus connections, poor connection in either area will likely lead to tripping. If bus connection has been overheated don't use that space it will never work well again - also replace breaker or it will likely just burn out another bus connection.
I would concur with kwire, to check the breaker's terminations. Remember that these breakers have thermal/ bimetalic elements which respond to heat. And heating of the termination will warm the breaker causing it not being able to carry the current that it should be able to carry.
Breakers are calibrated at 40degC to carry 100% of their rated current. Often times they are located is lower levels which may be significantly coole. At 25degC a 30a breaker should carry 33a before getting into the TC curve. Then NEMA AB4 for field testing breakers states that at 300% of its rated current the breaker should trip in less than 50sec.and of course with less current the time increases.
As such how can it be justified that the breakers is being tripped by an overload.
As pointed out by kwire check the breaker for heating, the stabs and wire connections. If you are there when the breaker trips pull the breaker immediately and check for localized heating at both ends of the breaker.
If you want to varify the actual load use a clap-on amp meter and check the actual current.
I should also point out that a breaker that trips thermaslly because of overload or becauseof heating will not be capable of being reset until it cools of a bit.
- Status