Fredrick Paget on sun 29 apr 01
Pam,
This is a real problem. It is not carbon but copper oxide that is the
culprit. Copper naturally oxidizes a little bit in the air and since the
oxide is not a good conductor it contributes an electrical resistance whi=
ch
causes localized heating. The heat makes the oxide grow thicker and when =
it
gets hot enough it softens the tension in the socket contacts, arcing
occurs, and the joint burns the plastic around it, Withdrawing the plug a=
nd
replugging it every once in a while will have the effect of removing a th=
in
oxide film through friction but if it has gone on for quite a while would
not do much good. Cleaning the blades of the plug with emery cloth and
cleaning the mating surfaces of the receptacle (after turning off the
electricity) would help too.
There is a product , of which I can not remember the name, that can be
rubbed on a copper connection leaving a thin chemically deposited coating
of silver. If this is done to both surfaces the problem does not occur.
This product is used in power work when making a joint between bus bars. =
In
power work there are silver plated fuse holders and fuses too.
Silver oxide is conductive so does not go through the vicious cycle.
A direct wired connection can be made tight enough so that the air can't
get into the joint to start the problem. It is your best bet since I have
never seen any high quality consumer plugs and receptacles with silver
plating. That kind of stuff is industrial and very expensive.
Fred Paget
>We had a kiln plug burn/melt down this last week on our Skutt kiln. We =
were
>told when looking into the problems of what caused this it was because c=
arbon
>can build up on the plug and it needs to be unplugged every 6 months or =
so.
>Is this for real?
>Pam
=46rom Fred Paget, Marin County, California, USA
L. P. Skeen on sun 29 apr 01
Pam,
This happened to me last year and scared the t-total hell out of me. If =
I
hadn't JUST moved behind the kiln to raise the window I'd have burns on m=
y
legs. I have no idea what caused the thing to short out and catch fire, b=
ut
there was plenty of carbon around AFTER the fire! ;) Never heard the
'carbon build up on the plug' theory, but it sounds interesting.
L
--
> We had a kiln plug burn/melt down this last week on our Skutt kiln.
Pam Pulley on sun 29 apr 01
We had a kiln plug burn/melt down this last week on our Skutt kiln. We w=
ere
told when looking into the problems of what caused this it was because ca=
rbon
can build up on the plug and it needs to be unplugged every 6 months or s=
o.
Is this for real? We were lucky that a coop member was working out in th=
e
area were the kilns are and heard what was happening, so no other major f=
ire
problems.
Pam
Michigan - sunny and nice finally
Robert and Mary Ann Sparacin on mon 30 apr 01
Dear Pam Pulley,
With constant use, the plug and receptacle oxidize and increasingly ge=
t hotter
till they fail. I do not think they are meant for the service they need t=
o provide.
Mine is starting to go as well. I solved the problem for now by getting a=
new 50
amp plug and socket at Home Depot, since I have to deliver some tile. In =
the mean
time, I think I will look around for an oversized switch box, maybe 100 A=
mp
capacity... this does not replace the fuse box, which is different. It wi=
ll only
act as an on/off device, which I like to have on an appliance, but it is =
not a
replacement for a fuse or circuit breaker, which regulates the rated ampe=
rage for
the unit. (ie: do not increase the circuit breaker amperage!!!)
RJS
Pam Pulley wrote:
> We had a kiln plug burn/melt down this last week on our Skutt kiln. We=
were
> told when looking into the problems of what caused this it was because =
carbon
> can build up on the plug and it needs to be unplugged every 6 months or=
so.
> Is this for real? We were lucky that a coop member was working out in =
the
> area were the kilns are and heard what was happening, so no other major=
fire
> problems.
>
> Pam
> Michigan - sunny and nice finally
>
> _______________________________________________________________________=
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> Send postings to clayart@lsv.ceramics.org
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Bret Hinsch on mon 30 apr 01
I had a meltdown a few months ago. Even though my cable was wired into a
large switch box by a professional electrician, I still had a meltdown.
In my case I think that the meltdown was caused by a piece of bisque trap=
ped
inside the elements. In the previous firing, a large coiled pot had
exploded. (It's very hard to get big pots perfectly dry during the rainy
season in Taiwan. I wanted to cry when I lost this one - it was a beauty=
..)
I was so depressed by the accident that I was lazy cleaning out the kiln,
and missed a big chunk of bisque that had gotten lodged between the coils=
=2E
I think that this foreign object caused the elements to overheat and melt=
ed
the plug. Fortunately it seems that no permanent damage was done. I had
the melted cable repaired, cleaned out the elements meticulously, and
haven't had any problems since.
Bret in Taipei
_________________________________________________________________
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Arnold Howard on mon 30 apr 01
I was test firing a kiln in the Paragon plant several years ago and
smelled burning plastic. The electrical outlet was over-heating, so
I turned the kiln off and had the outlet replaced.
This is one more reason we suggest monitoring the kiln during
firing.
Robert's idea of an electrical shut-off near the kiln is a good
one. We attach a label to the cords of Paragon kilns now (except
for 120 volt) recommending the shut-off box. We also recommend
disconnecting the power when the kiln is not in use.
Arnold Howard
Paragon
--- Robert and Mary Ann Sparacin wrote:
> Dear Pam Pulley,
>
> With constant use, the plug and receptacle oxidize and
> increasingly get hotter
> till they fail. I do not think they are meant for the service
> they need to provide.
> Mine is starting to go as well. I solved the problem for now by
> getting a new 50
> amp plug and socket at Home Depot, since I have to deliver some
> tile. In the mean
> time, I think I will look around for an oversized switch box,
> maybe 100 Amp
> capacity... this does not replace the fuse box, which is
> different. It will only
> act as an on/off device, which I like to have on an appliance,
> but it is not a
> replacement for a fuse or circuit breaker, which regulates the
> rated amperage for
> the unit. (ie: do not increase the circuit breaker amperage!!!)
>
> RJS
>
> Pam Pulley wrote:
>
> > We had a kiln plug burn/melt down this last week on our Skutt
> kiln. We were
> > told when looking into the problems of what caused this it was
> because carbon
> > can build up on the plug and it needs to be unplugged every 6
> months or so.
> > Is this for real? We were lucky that a coop member was working
> out in the
> > area were the kilns are and heard what was happening, so no
> other major fire
> > problems.
> >
> > Pam
> > Michigan - sunny and nice finally
__________________________________________________
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Cindy Strnad on mon 30 apr 01
Once again . . . .
If at all possible, do get your kiln hardwired in by a competent
electrician. The plugs that come with kilns, as far as I can figure out, =
are
meant for hobbyists who buy the kilns and then find they don't use them v=
ery
often. Any appliance that draws the kind of power a full-sized kiln draws
needs to be hard-wired unless you're just going to fire half a dozen time=
s a
year.
If you can't hard-wire it in, you'll need to inspect and replace the plug
periodically. You'll probably also need to have the cord and plug that ca=
me
with the kiln switched out for a heftier model. Plugs are harder for
electrons to cross than plain old wires, so there's more resistance--> mo=
re
heat--> more wear--> carbon build-up--> sparks and maybe flames.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Fredrick Paget on mon 30 apr 01
I found the product mentioned below at
http://www.thomasregister.com/olc/cool-amp/ it is called Cool-Amp.
They also have some kind of silver grease that might be good on plugs. I
don't know anything about it. It is expensive at US$46 an ounce but 1 oun=
ce
would be a lifetime supply.
Fred
>There is a product , of which I can not remember the name, that can be
>rubbed on a copper connection leaving a thin chemically deposited coatin=
g
>of silver. If this is done to both surfaces the problem does not occur.
>This product is used in power work when making a joint between bus bars.=
In
>power work there are silver plated fuse holders and fuses too.
>Silver oxide is conductive so does not go through the vicious cycle.
=46rom Fred Paget, Marin County, California, USA
Kenneth D. Westfall on mon 30 apr 01
The best idea is of course have all electric kilns hard wired. The next i=
s
once you cleaned or replaced you kiln plug buy some Nolox or other brand
name of product used when making aluminum wire connections. Come is
various size containers and is a little pricey but a little dab will do y=
ou
for a long time. Grease up the pug prongs with a coating to prevent
oxidation. Most electrical supply house and even Lowes should have it fo=
r
sell. All you need to ask is for that grease stuff you put on Aluminum wi=
re
connections.
Kenneth D. Westfall
Pine Hill Pottery
R.D. #2 Box 6AA
Harrisville, WV 26362
pinehill@ruralnet.org
http://www.pinehillpottery.com
Janet Kaiser on mon 30 apr 01
As a matter of interest, why do your kilns have and
allowed to have plugs? This also indicates loose cable
=66rom kiln to socket? It all sounds rather hazardous to
me.
Anything using high wattage like ovens or kilns would
be required to have a wired-up, built-in power box with
an integral on/off switch here in the UK. Cables have
to be through conduits up the wall to the switch too.
Wouldn't that be the safer alternative, even if
regulations (building and insurance) do not actually
require it of you?
Janet Kaiser
The Chapel of Art . Capel Celfyddyd
HOME OF THE INTERNATIONAL POTTERS' PATH
Criccieth LL52 0EA, GB-Wales Tel: (01766) 523570
E-mail: postbox@the-coa.org.uk
WEBSITE: http://www.the-coa.org.uk
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