I bought a heater to replace one that I had used for 5 years. Within a few weeks it was tripping every GFCI that I plugged it into. I bought another one that only lasted a couple of days.
I wrote an angry email to the manufacturer, and to my surprise they said “There may have been a problem potting them” and they’re sending me two new units.
The speed and ease makes me think maybe I’m not the first to have that problem and maybe they had a bad production run??? Is it possible I’m that I damaged them by letting them run with the water dried out, even thought there’s nothing in the manual saying not to, and in fact saying it’s “protected by multiple thermostats”. Could it be that my GFCI’s trip with Brand A but not Brand B and everything is perfectly fine?
It’s possible that the new one you bought is drawing much more current than the old one. Also, a GFCI will trip without an adequate ground connection. Are you using an old extension cord? Check it for damage, or corroded plug ends.
Double check the specs on the new heater and compare to the old one. If you don’t have the specs for the old one, try plugging in the heater to a different outlet, without a GFCI, and a higher rated breaker; see if it trips. Could be that simple.
Check for legitimate ground faults. Extension cords are notorious for this. I imagine an empty bird bath with a heater running in it would be prone to problems as well…any type of submersible heating element that is not submersed will inevitably over-heat itself much faster and more often than designed for, so the “multiple thermostats” are going to be overworked and overheated. Plus, an exposed heating element will corrode SUPER FAST. Corrosion = bad connections = tripping breakers and GFCI’s.
Failing these two suggestions - have someone with trained eyes look at the problem. There’s nothing better than actually seeing a situation firsthand. No offense, but an untrained person’s description of something often lacks important details. We can’t all be electricians, and there’s no shame in admitting that.
A GFCI does not care about the magnitude of current. (Of course, an over-current situation can cause problems. But your CB should trip when too much current is in the circuit.)
A GFCI receptacle does not need a ground connection; it will work fine even if you do not hook up the earth ground wire.
It detects the ground fault in the electrical device to which it is connected - it has nothing to do with whether the GFCI itself has a ground connection. This seemed quite clear…but I can see where the confusion came in. Read the rest of the words in the reply, it’ll all make sense. Where I mentioned a damaged extension cord as the thing to look for a ground fault.
A GFCI detects an imbalance in current between the hot and the neutral - this indicates that current is being lost to ground. A higher rated heater will be draw more current, so any current that was previously being lost over a bad ground in the extension cord will become larger in magnitude - and may go over the threshold that the GFCI is rated for.
Bigger heater drawing 15 amps - tiny ground fault - loses .03 amps. Trips GFCI.
It all depends on the ratings of each of the devices so it’s all hypothetical - but in any event - checking for damaged connections will probably fix all the problems.
A GFCI designed for personal protection – such as the GFCI receptacle in your bathroom – will trip when it detects a difference in current (between hot and neutral) that exceeds 4 to 6 mA, regardless of the magnitude of current. Industrial GFCIs that are designed to protect equipment have higher thresholds, typically around 100 mA.
At any rate, it sounds like there’s a ground fault w/ the heater. This is a dangerous situation, as a person (who is grounded) could get shocked by handling the heater. Depending on its design, operating the heater “dry” (i.e. not submerged) could very well cause the heater’s insulation to exceed its operating temperature and breakdown; check with the manufacturer on this.
I wasn’t explaining to YOU how a GFCI works. I as explaining it to the OP. Because they obviously didn’t know.
So you understand how a GFCI works. Do you know how electrical current acts as it travels through/along wires and cords? If there’s an imperfection in a cord or other connection, a larger magnitude of current will cause a larger amount of the current to bleed to ground. So since the OP noticed the problem when the heater was replaced, it’s entirely possible that the new heater is drawing more current than the old one and revealed a problem that the old heater didn’t.
Higher amp draw = more heat in the wires = more likely to magnify any imperfection or damage = more current (or an increase from zero to non zero) flowing to ground.
This here post, is directed at you Crafter_Man, and anyone else who wants to learn stuff, including maybe the OP if they ever return.
Sorry, but this is just plain wrong; leakage current is NOT dependent on total current draw. About the only situation that I can think of that would increase ground fault current would be leakage between the neutral and ground at the heater (higher current = more voltage drop = more voltage between neutral and ground). Conversely, a fault from the hot wire would actually decrease with current draw (as voltage is pulled down relative to ground). If the wires are getting hot enough that any fault would noticeably increase, then you need a better cord (normally, daily temperature changes, much less seasonal, would far outweigh any temperature rise in a cord used outdoors).
And of course current doesn’t have to flow through the ground (“bad ground in the extension cord”), bad or not (or even a two-prong extension cord with an adapter), for a GFCI to work.
I’m basing my understanding of this on actual in-the-field observations. I may be misinterpreting what I’m seeing if you say this is wrong.
I work on industrial equipment and in the case of an old machine with some dryrotted wires I often find that the control transformer’s fuse will blow when there’s a dead short to ground. If there’s not a dead short to ground, but just a weakness in some insulation, the current draw will increase on the transformer’s secondary (add up the draw of all components in the circuit and compare it to the actual readings plus a margin for dirty connections blah blah) but if it’s still less than the fuse is rated for it won’t blow. I’ve stuck higher rated fuses in a circuit for a customer who was too cheap to pay me to replace all the bad wiring in his 25 year old machine and got him through for a few more months until he broke something important. However, if they go ahead and add stuff to the circuit, which I’ve seen happen (directly wiring a trouble light into the 120v control circuit to provide semi-permanent lighting at an operator’s station) the fuse would start to blow again even though the added draw of just a 50 watt light bulb shouldn’t have been enough to push past the fuse’s rating.
So I realize that’s one very specific example and not directly related to the OP but do you mind explaining how an increase in the overall load of a circuit wouldn’t lead to a proportional increase in any losses through defects in the physical wiring of said circuit? Maybe some factor I overlooked?
Now I won’t sleep because of my stupid brain’s persistence at figuring things out, with or without me.
you put in over sized fuses? And you are a contractor? I hope you have high liability insurance. Sounds like so far you have been lucky. Keep increasing fuse size and some day someone will get hurt or there will be a fire. Along with your customer you will be held responsable. And if your customer claims that he did not know you were setting up a dangerous situation, it may be all yyours.
An increase in currrent flow will not cause an increase in leakage current. The amount of leakage currrent will depend on the insulation resitive value to ground and the voltage. I=E/R. Where I is leakage, E is system voltage, and R is the insulation resistance value. If the device is using more current yes the temperature of the insulation may increase. And with the increase in the devices current there will be a small voltage drop. Therefore R will decrease a small amount and E will decrease a small amount so I (leakage current) will be about the same.
Puhlease…going from a 1.75 amp fuse to a 2.75 amp fuse isn’t going to hurt anybody who wasn’t working hard on getting hurt already. I thought I made it clear that this was a control circuit in this case. Besides, when the customer asks for it in lieu of a legitimate repair against my recommendations, and signs off on paperwork saying as much, there’s no lawsuit to be had for anyone. You must be assuming I’m new or something.
Well that seems counter-intuitive to me, so as is true with all electrical theory, it must be right on the mark! I’m glad to know this now. I’ve been conflating voltage increase with current increase as regards grounding issues.
Old heater is 300 watts. New ones I’ve tried are 250. Outside it is on an old ratty (grouned) extension cord, but I took it inside and plugged it directly into the bathroom GFCI and it blew. If I did damage it by letting all the water evaporate I’m perplexed why the manufactur didn’t forsee that from happening and at the very least warn against it on the box or manual or something if they couldn’t design it for that eventuality. (It’s the Allied Precision Industries DT250)
I did a lot of rewirring once on elevator control circuit beccause someone up sized a fuse. Signed paper by customer means that he will be standing beside you not behind you in a court of law. You might get lucky, but many judges will ask did you know that up sizing a fuse was not safe, and your answer will determine how the judge may respond. Just saying.
On this instruction page,http://www.alliedprecision.com/manuals/ag/DT250.pdf
In the cautions, it will tell you to unplug the heater before removing from pond or tank.
That IS telling you that this heater isn’t suppose to run out of water.
AND, when you took it into the bathroom and plugged it in and as you described the results as it “blew” did you first put the heater into the freezer or have it cold enough to close the thermostat(s) thereby actually testing the unit?
Looks like you have a stock watering tank heater or a fish pond heater and with this unit wattage would dry up a birdbath very fast.
How many gallons is this birdbath???
Happy new year!
And the answer will be: Risk of injury is not increased by increasing the amperage rating on this fuse by this small amount. Risk of injury is increased by not maintaining equipment in proper working order. Risk of injury at 1.75 amps is the same as risk of injury at 2.75 amps. Provide colorful data sheet to support the idea that the temperature increase of an insulated conductor carrying 2.75 amps of at 120v is not enough to ignite any of the materials present in the electrical cabinet.
All components with which an operator might interact are fully insulated and removed from electrical current by at least *two *different non-conductive materials. Clear warnings are present all over the place, in redundant locations, and proper instruction is given every time I do a job because I know full well how lawsuits develop. If I had gone and stuck a 35 amp fuse on a 1 amp circuit, then I’d be pretty stupid, but I know full well what would happen even in that case. The “magic smoke” would be let out of the weakest component in the circuit - which is usually the transformer - and since all the components are located within a fire-rated electrical cabinet there would be no added risk.
Also, you’re making some logical leaps here, which I didn’t flesh out because it was totally irrelevant. When things get really hairy, and there’s an obvious case to be made that a machine is wholly unsafe regardless of my involvement, or in danger of starting an electrical fire, I don’t work on it without the customer agreeing to repair ALL damage and defects.
I once worked on a piece of equipment where the designer selected a fuse rating that was too low, as it would occasionally blow under heavy (but normal) loads. I increased the rating of the fuse and it solved the problem. The larger fuse was still sufficient to protect the internal wiring and connections from damage due to over-current.
But I agree that you should never increase the size of a fuse simply due to nuisance trips. The rating of a fuse or C.B. should only be changed after a careful analysis of the system. This would include load current measurements, temperature rating of wire insulation, and temperature rating of movable and stationary contacts.
The birdbath is probably a couple of gallons, so it’s hard to keep it from drying up unless I top it off every day when it’s cold. I tried a small heater rated for 50 watts but it wasn’t enough to get the job done.
When I tried it out inside, I had just taken it inside so it was chilled from being out in the cold.
I recall the old unit said specifically not to run it dry, but it lasted for several years even with being abused. Granted I should have read the manual more carfully, but normally you expect to see something like “RUNNING UNIT DRYWILL WRECK IT AND VOID WARRENTY AND CAUSE THE MAYAN APACOLYPSE”, not an instruction at the end buried within a bunch of “don’t be an idiot and sue us stuff”.
And plantif’s attorney will ask you have been maintaining this equipment? And Risk of injury is increased by not maintaining equipment in proper working order. So you knew the equipment was not in proper working order and you increased the fuse size so a safety will not stop the equipment? Remember one famous lawyer on TV said “it all depends what is means”.
I had a job once where I had to reset a heating boiler often. Could not get the manager to replace the boiler that winter. The next next year I refused to llight the boiler off. When the manager reralized it was going to be his resonsibality not mine they got a new boiler.
So you assume the answer to that question would be “Yes, I have been maintaining this equipment” instead of “Nope, just there for that one job. Told him to fix it right, he declined.”
When you re-read the rest of the post, you’ll see that neither you nor your hypothetical prosecuting attorney would have any leg to stand on, and this is intentional. It’s how I do business, and it works.
Just saying - read it all instead of only the parts to which you feel a reply will make your point.
A easy way to visualize this is a circuit with two lightbulbs; a 1 watt bulb to represent leakage current and a 100 watt bulb to represent load current. Changing the 100 watt bulb to 200 watts won’t affect the 1 watt bulb. Basically, you have a parallel circuit, where current flow is independent (ignoring voltage drop) between devices.
Also, re: fuses, in most electronic equipment, fuses are often overrated, sometimes extremely so; e.g. a 90 watt power supply with a 6.3 amp fuse; power supplies of similar wattage that I build might use a 2 amp fuse (slow-blow due to inrush, as are most fuses in electronics), which still provides a good margin. This of course leads to observations like $5 transistors (and other parts) blowing to save 10 cent fuses (and they may still blow, as in exploding and breaking the circuit, anyway before the sensibly rated fuse does). Replacing the fuse with one of a higher rating would have even worse results, although there may be situations where it is recommended to uprate a fuse (not too much!) if it keeps blowing with no fault.
