Lee 4-20 melting pot issues

Hi guys.

For my sins I currently live in the UK. I have recently acquired a Lee 4-20 lead pot in 220v which is giving a little trouble. The thing keeps tripping my circuit breaker A GFI I think it is called in the USA. It also buzzes in use until it trips the breaker. Now I don't know if the buzzing is normal but I do know that tripping a 16A breaker is not for a 750 watt element. Would I be correct in thinking that as a GFI detects earth leakage there is an earth fault somewhere in the circuitry? It is obvious that it is not drawing too much power as in the UK we have to use fused plugs in this case a 13A fuse and that fuse is not blowing so it has to be an earth (ground) leak. Yes?

I am not sure what the problem is, but I can tell you that mine buzzes when heating. It is not loud, but when it gets up to temp, the buzzing stops, and starts again when the element kicks back on. Welcome to the forum!

I would try it on a different outlet (that's not on the same breaker/circuit) first to see if it's the pot or the breaker/circuit.

If it's the pot, I would return it for a replacement.

There's not a whole lot to these pots that can go wrong. Power comes in, goes through a thermostat goes to the heating coil.

I think that's a breaker issue and not a Lee pot issue.

It is possible the pot has a high resistance short (the buzzing/arcing sound).
Open the pot up & look for signs of arcing.

I'd bet it's the GFI outlet. Can you plug it into a regular outlet and see if it causes the same issue? If it was a fault it would trip as soon as it turned on. I got the rebuild kit for mine just for fun & rebuilt it. Open it up check for anything that looks like it may be causing an issue. You can also test the resistance of the element, continuity test the circuit to frame ground.
You can also read this thread: http://castboolits.gunloads.com/show...ing-pot-broken

Given that the 13 amp plug fuse did not blow, I would say that there is a faulty breaker or the GFI breaker is sensing leakage to ground and tripping the breaker.

Does the melter have a three pronged plug on it? The third prong being a ground wire connection.
If not, I do not see how the GFI would sense ground leakage from the melter, unless the melter was on a metal surface that was grounded somehow.

Perhaps plug the melter into another 220 volt GFI protected circuit and see if the problem persists.

My bet is on a faulty GFI breaker and needs replacing.

I disassembled the pot and connected the element directly to the mains using the same outlet as previously used and the element heated perfectly I left ir running for 40 mins and the breaker did not trip it was the main breaker that was tripping not the breaker for the outlet circuit. I did not have the LEE control switch in the circuit at the time of the test, it would therefor seem that it is the temperature adjuster switch that is at fault since that is the only part that is likely to fail and is the only electrical component with moving parts. The buzz was loud and at 50Hz (UK AC frequency) if the rather flimsy Lee adjuster was vibrating there would have been multiple on/off cycles, thereby tripping the breaker. Replacing the Lee control switch with a more sturdy device should resolve the issue. Alternatively, I will simply bypass the control switch entirely and run without it. I think that replacing the switch with a PID with a thermocouple and solid state relay will be the safest option though either that or a switch from an electric cooker (cheaper).

Glad you got it figured out.
Seems like a lot of work to fix a minor problem. Why not just use another circuit that doesn't have a GFI breaker OR just replace the GFI breaker with a standard type? Sounds like you have two GFI breakers on the same circuit (one at the outlet and one at the breaker box)

A faulty thermostat is very likely, glad you found it.

I would highly recommend going the PID route, life is soooooooooo-- much easier when you know exactly what temperature your at and not having to adjust the dial and watch a thermometer.

Quote:

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Originally Posted by Briantllb

Alternatively, I will simply bypass the control switch entirely and run without it. I think that replacing the switch with a PID with a thermocouple and solid state relay will be the safest option though either that or a switch from an electric cooker (cheaper).

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I've pulled the switches from my Lee pots that I use with a PID.

g'luck!

It's not a thermostat. The Lee control is a glorified buzzer. It is slightly affected by heat from the pot but it's a screw putting bias on a spring that determines the what percentage of the time the element is on. It's why PID is so popular with Lee Owners.

3 wire plug? GFIs match both lines and determine if electricity is going elsewhere. There needs to be an elsewhere or the GFI is defective.

I wouldn't run without any control. New Lee controls here are $10, if you contact them they may just send you one.

I wholeheartedly recommend a pid. I just hooked one to mine and turfed the oem lee temp controller. The temp probe is a screw type that is pushed up against the bottom of the pot. Works an absolute treat.