Plugs hot to the touch...

[ZenStalinist]

I have an oil-filled radiator that draws 11 amps maximum. It is controlled by an X10 appliance controller, yet yesterday I noticed that the plugtop was quite warm. The x10 unit wasn't too warm, and the plug for the four way extension lead it was plugged into was only a little warm, nowhere near as warm as the heater plug. The three-way socket that was plugged into was fine, not heat at all. I unplugged the heater plug from the x10 unit, and I made the mistake of touching the live pin. hot-hot-hot ... owww
The neutral pin was also very hot and the earth pin was kind of warm - I assume this is just heat dissipation...
I believe my x10 unit is designed to handle such wattages, and it works fine for hours without blowing any fuses... I always thought plugs were never supposed to be warm to the touch... is this okay?

 

[breezer]

if something electrical is hot then it is showing signs of a fault, i would recomend change the plug, try an MK brand

 

[ZenStalinist]

I just ran it for 30 mins on full power without the X10 unit (and as a result I am boiling here), had the plug isn't really hot this time. So it's probably the x10... I'll check with the manual what the maximum load is... I didn't think there was one.

 

[ban-all-sheds]

Maybe it's just a poor connection between prong and socket in the X10?

 

[ZenStalinist]

Maybe... It says it can handle resisitive loads of up to 16 amps (though it is fused at 13 amps, naturally)

I might get another appliance module to try it with...

 

[breezer]

technicaly a heater is not a resitive load, its inductive (because its a coil)

 

[ZenStalinist]

Hmm... I read on a website as one of the examples, a heater was listed as a resisitive load. But if the heater is an inductive load, then the maximum capacity would be 1a, which might explain my problem.

 

[breezer]

it really depends on how big its coil is and how its wound, i did say "technicaly"

 

[Big_Spark]

Breezer, the sort of heater we are talking about here will be classed as a Resistive load not an inductive load. Picking hairs it may be, but that is what it is.

However I have heard of similar problems with X10 units and high loads. It seems that X10 units are ok for a short while with heavy loads, but after some time being used to comtol them the plugs get hot as the units do not like it.

I would point out this is only what I have heard, I have no personal experience of this so this may not be the problem.

 

[breezer]

Breezer, the sort of heater we are talking about here will be classed as a Resistive load not an inductive load. Picking hairs it may be, but that is what it is.

i did say "technicaly" its inductive, but obviously it depends on coil

 

[Stod]

i did say "technicaly" its inductive, but obviously it depends on coil

Not even technically.

The point is that switches have to be derated for inductive loads because only they can dissipate the stored energy when the circuit is opened. In the example, nearly all of the stored energy in the tiny inductance of the heating coils will be dissipated by the resistance.

 

[breezer]

ok, ill get my coat

 

[ban-all-sheds]

The ability of the X10 to switch a load has no bearing on whether it will get hot in normal operation. If you give it the wrong load to switch then you will get arcing when the switch opens and the contacts will be damaged, but it won't gt hot just by passing the curent.

OK - so if you have damaged contacts then you could get overheating in the X10 controller, but it's been stated that this is not where the heat is coming from.

My vote still goes to a poor contact within the X10 unit between the unit and the pins of the plug. And because the mass of brass is much higher in the plug than in the little springy contacts in the X10, this is where the heat accumulates.