From Newsgroup: alt.home.repair

I had a dehumidifier installed under the house last year. The
dedicated wiring goes through a GFCI then to one side of a circuit
breaker with two 15 amp sides. The breaker is designed to take up only
one slot in the electrical panel but used for two separate circuits.

Recently the breaker has been tripping every so often. The GFCI does
not trip. The electrician from the company troubleshot it yesterday
with a clamp style amp meter around the wire. He turned the
dehumidifier on/off with the GFCI and noticed if there isn't sufficient
rest time, the initial surge of current goes all the way up to 35 amps
which then trips the circuit breaker. After a few times he declared
the dehumidifier bad and it's getting replaced under warranty.
Apparently they've seen this before with that model.

Why would the GFCI not trip before the circuit breaker? Why would a 15
amp circuit breaker trip at an initial surge of 35 amps rather than 15
amps? Is this as designed? Seems like quite a large margin.
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From Newsgroup: alt.home.repair

On 6/25/2026 8:40 AM, badgolferman wrote:

I had a dehumidifier installed under the house last year. The
dedicated wiring goes through a GFCI then to one side of a circuit
breaker with two 15 amp sides. The breaker is designed to take up only
one slot in the electrical panel but used for two separate circuits.

Recently the breaker has been tripping every so often. The GFCI does
not trip. The electrician from the company troubleshot it yesterday
with a clamp style amp meter around the wire. He turned the
dehumidifier on/off with the GFCI and noticed if there isn't sufficient
rest time, the initial surge of current goes all the way up to 35 amps
which then trips the circuit breaker. After a few times he declared
the dehumidifier bad and it's getting replaced under warranty.
Apparently they've seen this before with that model.

Why would the GFCI not trip before the circuit breaker? Why would a 15
amp circuit breaker trip at an initial surge of 35 amps rather than 15
amps? Is this as designed? Seems like quite a large margin.

My understanding, not necessarily accurate, is that the GCFI trips if
there is more than only a few milliamps of stray induced current flowing through the circuit's ground wire. The current measured by the clamp-on ammeter measures current flowing through any two of the three wires in
the circuit. The surge that's tripping the breaker is flowing through
the hot and neutral wires and doesn't involve the ground wire (probably
green in color but it could also be an un-insulated, bare wire. GCFI is designed to detect a bad ground connection. It is not a surge
protector. If your dehumidifier draws an excessive surge when starting
up, it would trip a normal, non-GCFI 15 amp breaker as well. It's not
the GCFI feature that's causing that breaker to trip. I'm sure I'll be corrected if I've got this wrong.
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From Newsgroup: alt.home.repair

On Thu, 25 Jun 2026 12:40:13 -0000 (UTC), "badgolferman" <REMOVETHISbadgolferman@gmail.com> wrote:

I had a dehumidifier installed under the house last year. The
dedicated wiring goes through a GFCI then to one side of a circuit
breaker with two 15 amp sides. The breaker is designed to take up only
one slot in the electrical panel but used for two separate circuits.

Recently the breaker has been tripping every so often. The GFCI does
not trip. The electrician from the company troubleshot it yesterday
with a clamp style amp meter around the wire. He turned the
dehumidifier on/off with the GFCI and noticed if there isn't sufficient
rest time, the initial surge of current goes all the way up to 35 amps
which then trips the circuit breaker. After a few times he declared
the dehumidifier bad and it's getting replaced under warranty.
Apparently they've seen this before with that model.

Why would the GFCI not trip before the circuit breaker? Why would a 15
amp circuit breaker trip at an initial surge of 35 amps rather than 15
amps? Is this as designed? Seems like quite a large margin.

The GFCI trips on _tiny_ <milliamp> _imbalance_
in the current carrying wires or tiny flow in the ground wire.
Breakers and fuses have a time-curve to allow short duration
"overload" for starting surges. I've heard that breakers can go
weak if they have been tripping a lot .. if it wasn't a warranty job replacing the breaker might be a first-step ..
John T.
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From Newsgroup: alt.home.repair

"badgolferman" <REMOVETHISbadgolferman@gmail.com> writes:

I had a dehumidifier installed under the house last year. The
dedicated wiring goes through a GFCI then to one side of a circuit
breaker with two 15 amp sides. The breaker is designed to take up only
one slot in the electrical panel but used for two separate circuits.

Recently the breaker has been tripping every so often. The GFCI does
not trip. The electrician from the company troubleshot it yesterday
with a clamp style amp meter around the wire. He turned the
dehumidifier on/off with the GFCI and noticed if there isn't sufficient
rest time, the initial surge of current goes all the way up to 35 amps
which then trips the circuit breaker. After a few times he declared
the dehumidifier bad and it's getting replaced under warranty.
Apparently they've seen this before with that model.

Why would the GFCI not trip before the circuit breaker? Why would a 15
amp circuit breaker trip at an initial surge of 35 amps rather than 15
amps? Is this as designed? Seems like quite a large margin.

The GFCI is not a circuit breaker. It detects ground faults,
not overcurrent conditions.
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From Newsgroup: alt.home.repair

On Thu, 25 Jun 2026 14:46:58 GMT, scott@slp53.sl.home (Scott Lurndal)
wrote:

"badgolferman" <REMOVETHISbadgolferman@gmail.com> writes:

I had a dehumidifier installed under the house last year. The
dedicated wiring goes through a GFCI then to one side of a circuit
breaker with two 15 amp sides. The breaker is designed to take up only
one slot in the electrical panel but used for two separate circuits.

Recently the breaker has been tripping every so often. The GFCI does
not trip. The electrician from the company troubleshot it yesterday
with a clamp style amp meter around the wire. He turned the
dehumidifier on/off with the GFCI and noticed if there isn't sufficient >>rest time, the initial surge of current goes all the way up to 35 amps >>which then trips the circuit breaker. After a few times he declared
the dehumidifier bad and it's getting replaced under warranty.
Apparently they've seen this before with that model.

Why would the GFCI not trip before the circuit breaker? Why would a 15
amp circuit breaker trip at an initial surge of 35 amps rather than 15 >>amps? Is this as designed? Seems like quite a large margin.

The GFCI is not a circuit breaker. It detects ground faults,
not overcurrent conditions.

Had the same problem with my central vac. It was determined to be the
surge current on startup - which required a "high magnetic" 15 amp
breaker. Single 15 amp high mag breakers are not carried in Ontario
and I wasn't about to order one from Quebec. I called Square D and
they told me all 2 pole Squsre D breakers were high magnetic so I
just threw in a 2 pole in (thankfully I had space) and the problem was
solved.
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