Electrical Engineering - AFCIs and lightening

Author

AFCIs and lightening

Gus

2006-06-29, 9:26 am

From the first month in a new house I have had problems with the AFCI
tripping in the master bed room. All it takes is a small electrical
storm. Thunder does not make a difference so vibration is not the
problem.

Last Friday the AFCI in the master bedroom tripped some time around
or during a small storm.

Saturday the electricity fluxuated all day causeing my UPSs on my
computers in the other AFCI protected room to buzz and rest.

Saturday we had another smaller storm and BOTH AFCIs tripped. A first
in the two small bed rooms.
Also a CFCI on the end of a 330' run to the automatic gate tripped.

Lightgening is killing me here, can anyone help.

The electrical contractor has replaced the AFCI s four times and now
wants to replace the run from the pannel to the main tie-in point in
the master bedroom. Thi will tear the hell out of my insulation and
wireing n the atic.

Thanks for any help. A local electrician told me this problem is
somewhat typical.

Salmon Egg

2006-06-29, 9:26 am

On 6/26/06 8:33 PM, in article s891a2dh3vkpeito7s84161cqbch49va27@4ax.com,
"Gus" <gus@etex.us> wrote:

> From the first month in a new house I have had problems with the AFCI
> tripping in the master bed room. All it takes is a small electrical
> storm. Thunder does not make a difference so vibration is not the
> problem.
>
> Last Friday the AFCI in the master bedroom tripped some time around
> or during a small storm.
>
> Saturday the electricity fluxuated all day causeing my UPSs on my
> computers in the other AFCI protected room to buzz and rest.
>
> Saturday we had another smaller storm and BOTH AFCIs tripped. A first
> in the two small bed rooms.
> Also a CFCI on the end of a 330' run to the automatic gate tripped.
>
> Lightgening is killing me here, can anyone help.
>
> The electrical contractor has replaced the AFCI s four times and now
> wants to replace the run from the pannel to the main tie-in point in
> the master bedroom. Thi will tear the hell out of my insulation and
> wireing n the atic.
>
> Thanks for any help. A local electrician told me this problem is
> somewhat typical.

Make sure that there is no significant capacitance between hot and ground.
Capacitive current to ground can trip.

Bill
-- Ferme le Bush

Gus

2006-06-29, 9:26 am

Thanks Bill:

I'll talk to the electrician about that. I understand capacitance in
electronics but where would it come from in an electrical system?

BTW - the electricity going out and the storms almost always occur
during the night. At those times I have a Hunter ceiling fan on, it
has some kind of solid state circuit. In the rooms where the AFCI
does not trip, the fans are always off at that time.

Gus

On Tue, 27 Jun 2006 04:37:20 GMT, Salmon Egg <salmonegg@sbcglobal.net>
wrote:

>On 6/26/06 8:33 PM, in article s891a2dh3vkpeito7s84161cqbch49va27@4ax.com,
>"Gus" <gus@etex.us> wrote:
>
>
>Make sure that there is no significant capacitance between hot and ground.
>Capacitive current to ground can trip.
>
>Bill
>-- Ferme le Bush
>

Salmon Egg

2006-06-29, 9:26 am

On 6/27/06 5:49 AM, in article it92a25fufbdb68o7am4nl1i45jaibv7rq@4ax.com,
"Gus" <gus@etex.us> wrote:

> I'll talk to the electrician about that. I understand capacitance in
> electronics but where would it come from in an electrical system?

There is the capacitance just between wires, but that is probably not
enough. If there are any surge suppressers around, some of them night add
some filtering by connecting capacitors from the line conductors to ground.

I also once had a submersible pump that had leakage from the motor winding
to ground. It was not enough to be a hazard if the pump case was properly
grounded. When the pump was turned off, there often was enough of an
inductive kick to trip. All these leakage currents add together to lower how
much additional leakage current is required to cause a trip.

Bill
-- Ferme le Bush

Bud--

2006-06-29, 9:26 am

Salmon Egg wrote:
> On 6/27/06 5:49 AM, in article it92a25fufbdb68o7am4nl1i45jaibv7rq@4ax.com,
> "Gus" <gus@etex.us> wrote:
>
>
>
>
> There is the capacitance just between wires, but that is probably not
> enough. If there are any surge suppressers around, some of them night add
> some filtering by connecting capacitors from the line conductors to ground.
>
> I also once had a submersible pump that had leakage from the motor winding
> to ground. It was not enough to be a hazard if the pump case was properly
> grounded. When the pump was turned off, there often was enough of an
> inductive kick to trip. All these leakage currents add together to lower how
> much additional leakage current is required to cause a trip.
>
> Bill
> -- Ferme le Bush
>

Not explicitly stated - AFCIs include ground fault protection and trip
at 30 ma. (GFCIs trip at 5 ma.)

A surge suppressor downstream from an AFCI (or GFCI) intercepting a
surge from lightning, or other, could cause a trip (shunting the surge
to the ground wire). Same for a UPS with built in surge suppression.
Another possible is current to ground through circuit capacitance
resulting from fast rise time on a lightning induced surge.

[Do AFCIs and GFCIs trip on very short ground faults?]

Sounds like the trip could be from the Hunter fan. You could try running
the fan in the other bedroom(s) when you anticipate a storm to see if
that AFCI trips with the fan on.

If caused by lightning induced surges a service panel surge suppressor
may help (is a good idea anyway).

Replacing the wire from the pannel to bedroom would only help if there
is a problem with the wire - seems remote. Unless the electrician sees
some other problem.

bud--

Gus

2006-06-29, 9:26 am

Thanks for the note Bud. >

On Wed, 28 Jun 2006 10:39:47 -0500, Bud-- <remove.BudNews@isp.com>
wrote:

>
>Not explicitly stated - AFCIs include ground fault protection and trip
>at 30 ma. (GFCIs trip at 5 ma.)
>
>A surge suppressor downstream from an AFCI (or GFCI) intercepting a
>surge from lightning, or other, could cause a trip (shunting the surge
>to the ground wire).

I have a GFCI on an expernal house circuit that was intended to run to
a well. I have it running to an automatic gate, only thing on the
circuit. It has been found tripped after electrical storms before.

There has been a power strip in the master bedroom circuit for he tv
and vcr. And of course, the Hunter fan that was on, and an alarm
clock.

The other AFCI breaker protects the other two bedrooms. One room is
my computer room that has two UPSs. This AFCI has never tripped
before, before the incident last weekend when both the AFCIs tripped.
> Same for a UPS with built in surge suppression.

>Another possible is current to ground through circuit capacitance
>resulting from fast rise time on a lightning induced surge.
>
>[Do AFCIs and GFCIs trip on very short ground faults?]
>
>Sounds like the trip could be from the Hunter fan. You could try running
>the fan in the other bedroom(s) when you anticipate a storm to see if
>that AFCI trips with the fan on.

This is a 52" ceiling mounted fan. I can leave the other two Hunter
fans on in the other bedrooms and the one off in the Master bedroom.
Switching out the 52" would be a lot of work.
>
>If caused by lightning induced surges a service panel surge suppressor
>may help (is a good idea anyway).

Now that's an idea the electrical company did not come up with. A
panel surge suppressor can't cost more than rewiring the bedrooms.

>
>Replacing the wire from the pannel to bedroom would only help if there
>is a problem with the wire - seems remote. Unless the electrician sees
>some other problem.

Hey, these "electricians" are who knows what, working under someone's
license. They don't see anything. They had to come back and tighten
all of the wall switches and outlets because a finisher did not
tighten the screws on the devices.

This is a new house that I babysat while it was being built. I saw
nothing in the wiring that was suspicious and thought they did a great
job.

Thanks for the suggestions I'll take to the contractor.
>
>
>bud--

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