Thats sounds like a good explanation to me. I would also question the draw
of the appliance. It burned two receptacles and it's not a factory plug.
There is a good possibility that it should be a 20 amp plug and not 15 as
Good possibility? It is a definite FACT. With the 30 amp rating of the
conditioner,a 20 amp plug would be a requirement. Particularly on a 20
And I'm still asking if this is a ferro-resonant regulator device.
Don't assume a 30A rating requires a 30A plug. That rating is the
maximum input current, and you can absolutely change the plug to a lower
rating if the load on the conditioner is less than full load. The
circuit protection is at the panel feeding the receptacle, so if that
receptacle is on a 15A or 20A circuit it is fine. If the load is too
high the breaker will trip.
We don't know what size breaker is on the circuit. We don't know what
the actual load amperage on the circuit is. It's entirely possible that
a bad connection caused overheating of the contact at well below even a
I know that. Are you confirming what I wrote or disputing something?
Read the last sentance of the post up a couple levels.
It reads: If the load is too high the breaker will trip. So if the
breaker didn't trip, then maybe, just maybe someone is wrong when they
say "a 15 or 20 amp circuit is fine". Maybe if it had a 30 amp outlet
it would have made a better connection and never happened?
In the past I have changed 30A plugs on a UPS out for 20A plugs, since
the application had the UPS operating well below it's maximum ratings
(mostly sized for run time). This was perfectly safe since the 20A
receptacle was protected by the 20A circuit breaker, so if someone
improperly added loads to the UPS the breaker would simply trip.
Receptacle contact areas don't dramatically increase with current
rating. Yes, a 60A contact is notable larger than a 15A one, but there
isn't a lot of difference between a 15A and a 30A in many connector
styles (twistlock in particular).
The point here is that this is likely the result of a loose connection
in the plug, and nothing else.
It is a 20 amp receptacle according to the OP, and the device (still
has not been established white kind of "conditioner") is rated at 30
It NEEDS a 20 amp plug. To handle up to 20 amps input current.
If it is a Ferro conditioner, that means it's good for about 15 amps
out. They are quite effective heaters.
That's such a screwed up fiasco from what I've seen/read, that it has to
have a 30A fuse and likewise be wired for "stopped rotor" & whatever
applies. We have no idea really what the situation is, wire gauge, voltage
during draw and resulting damage to inductive parts (motors, relays coils,
What they need to do is get a real electrician in there to install things
correctly; they've made way too many bad choices. And then of course have it
inspected. It would not pass inspection right now.
The wire and connectors must be capable of carrying 80% of the load of
everything on that ckt breaker. Since it's a 15A plug/receptacle and one
piece of equipment is 30A I'd have to surmise they're using a time-delay
breaker for one, that lets them slip by without popping the brkr, but : It
is NOT to code! OSHA would have a field day with it, too. As would NFPA. I'd
be interested also in what gage wire is being used to the box and to the
other components drawing current?
Sounds like a pretty dangerous place to work to me.
That is what I think also. That is an after market plug (note the
screws holding it together). It was not assembled correctly with a poor
connection on the ground side. Replace it and the now damaged outlet.
You can always feel the plug and see if it is unduly warm, always a sign
of a poor connection.
Bad (high resistance) connection between the plug & receptacle neutral
I'm betting that it took a fair amount of time (many months) for the
problem to manifest.
Get a better grade of receptacle & plug.
Make sure that the plug withdrawal force is good.
The fuse (circuit breaker?) never did its job because the amperage
draw was lower than its rating.
If it is a high resistance connection (which it may well be) there is
no arc. One may develop later.
If there is an arc, it is a "series" arc. The original AFCIs won't
detect it; they need an arc of around 50A (line to neutral or ground).
The AFCIs installed 2008 and later can detect a series arc. AFCIs have
only been around since 2002 and only for residential (this is office).
But wait a few years. Required use is creeping like a slow plague in
every NEC revision.
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