Pressure washer keeps tripping breaker - Page 1
Forum section: electronics / repair

author: Hogwild
author_rank: Regular Contributor
timestamp: October 07, 2019, 09:07:28 pm
content: Hi everyone:I have a typical but old (12 years) pressure washer that keeps tripping the breaker. I'm wondering if the large capacitor inside it has blown. What are the main reasons for a pressure washer to blow a breaker? BTW, I've tried it on different circuits and with or without extension cords. Neither change made any difference.Is it worth replacing the capacitor?

author: SparkyFX
author_rank: Frequent Contributor
timestamp: October 07, 2019, 09:12:21 pm
content: Depends on the type of motor. Could also be winding shorts, water ingress or choked tubing/check valves.The starter/run capacitors are largely self-healing, without it it would probably not run at all. Does it make a few turns and then trips the breaker or right from pulling the trigger?

author: Hogwild
author_rank: Regular Contributor
timestamp: October 07, 2019, 09:16:33 pm
content: It's all over the place. Last year, once it would "warm up" for a while, it would tend not to trip the breaker. This year, it's tripping it fairly regularly.

author: Gregg
author_rank: Super Contributor
timestamp: October 07, 2019, 10:32:29 pm
content: There are lots of possibilities for an electric pressure washer to trip a breaker.1. Moisture could have contaminated the winding insulation causing partial short circuits between windings and/or to ground2. The pump side could have mineral deposits from hard water causing excessive load on the motor3. The start winding switch may not be working correctly [if it has such a switch]4. The bearings in motor and pump may be bad due to moisture or bad seals5. Pump valves may be sticking6. The circuit breaker may be “tired” from tripping too many times7. The voltage may be low due to bad connection(s)That’s just a few items off the top of my head, I’m sure there are more possibilities. Do you have a clamp ammeter to check the actual current draw?

author: Hogwild
author_rank: Regular Contributor
timestamp: October 07, 2019, 10:57:44 pm
content: Oh, my! That doesn't sound like fun checking all those things.I didn't use a clamp meter per se, but I did use a Kill-A-Watt. Can't remember what the exact wattage was, but at one point, it started up using something like 1800 or 1900 watts. This was on a 15 amp circuit.

author: Gregg
author_rank: Super Contributor
timestamp: October 07, 2019, 11:37:51 pm
content: If it is a TEFC (totally enclosed fan cooled) motor, it may have a fan cover on the end opposite the pump that is removable which would allow you to turn it over by hand and determine if it rotates freely

author: Hogwild
author_rank: Regular Contributor
timestamp: October 08, 2019, 12:58:43 am
content: Ummm...I feel kind of dumb asking this, but if it weren't turning freely, would the machine pump water at high pressure at all?And...would #2 in Gregg's list be mitigated by pumping diluted vinegar through the washer? The manufacturer recommends this for clogs, so I thought it might be okay.

author: TheMG
author_rank: Frequent Contributor
timestamp: October 08, 2019, 01:08:58 am
content: Is this the type of pressure washer when the electric motor runs all the time, or only when you pull the handle on the spray wand? If it's the type where it runs all the time, does the overload condition occur only when you are not spraying? When spraying? Both?I would suspect a valving/flow/pressure issue before the motor itself. If the pressure is allowed to get too high for whatever reason, it will increase the load on the motor causing it to draw more power.

author: james_s
author_rank: Super Contributor
timestamp: October 08, 2019, 01:11:07 am
content: Most of the electric pressure washers I've seen had a crappy universal motor, if this is the sort you have then I suspect the brushes may be getting worn. Is it plugged into an arc-fault breaker by chance? Those are notorious for nuisance trips by universal motors in vacuum cleaners and such.

author: Hogwild
author_rank: Regular Contributor
timestamp: October 08, 2019, 01:22:19 am
content: I only hear a louder noise when I pull the trigger. When the trigger is not pulled, I hear a faint hum or (after a short while) silence. What does that mean?No, it's plugged into a standard grounded outlet.

author: james_s
author_rank: Super Contributor
timestamp: October 08, 2019, 01:23:28 am
content: It sounds like the motor starts up when you pull the trigger, then keeps running for a bit in case you pull the trigger again, then eventually shuts off to save power when it has not been used in a while. If it makes only a soft hum it may actually be an induction motor, universal motors scream.

author: Hogwild
author_rank: Regular Contributor
timestamp: October 08, 2019, 01:38:36 am
content: It definitely doesn't scream. It's reasonably quiet, even when it's pumping tons of water. If I'm somewhat mechanical, will the problems mentioned in the above list be fairly obvious if I take apart the unit?Would posting photos of the internals help?

author: beanflying
author_rank: Super Contributor
timestamp: October 08, 2019, 01:56:15 am
content: 'Blow the breaker' is that just an overload or an earth leakage type?If it is tripping due to earth leakage then you most likely have blown seals on the pump and water or at least moisture in the motor so don't use it until you fix it. In some cases there is a small hole at or near the junction between the pump and motor, if you see evidence of water here your seals are gone.If that is more than your breaker will handle (test with a clamp meter) or as others have offered up the breaker is tired at least you can eliminate or confirm the breaker is at fault.These cut down cheapy pressure washers eliminate some of the normal protection bits on the better units. Being a piston pump if the cut down pressure relief valve / pressure switch is clogged or set to high then likely you will be drawing more current as it will be trying to push more pressure which translates to more power needed by the motor. If there is a pressure control knob visible or even available with the covers off back it off and retest.Vinegar is not the answer to feed to the pump if your water has caused calcium build up more likely you will have chunks break off and wreck the rubber seals. Strip it down and clean with a hot Citric Acid bath to dissolve calcium or maybe vinegar but Citric is my go to for Coffee Machines and Calcium. In situ decalcifying almost always ends in tears.

author: amyk
author_rank: Super Contributor
timestamp: October 08, 2019, 02:29:05 am
content: Yes, pictures are always appreciated.Especially ones of the motor, since that can help us determine exactly what type it is. By your description it's likely an induction motor, but there's a bunch of different variants of those too (PSC, CSR, CSCR, etc.)

author: Tom45
author_rank: Frequent Contributor
timestamp: October 08, 2019, 02:43:41 am
content: My pressure washer will sometimes trip the breaker in my shop if I forget and leave the pressure washer's power switch on when not in use.As long as I turn off the power switch on the pressure washer and turn off the water supply to it when not in use, it never trips the breaker. If I get distracted and forget to turn off the power switch and water supply after using it, it will sometimes trip the breaker.

author: Hogwild
author_rank: Regular Contributor
timestamp: October 08, 2019, 03:10:03 am
content: Jeez, it's amazing how much you folks know. So, with all this in mind, I don't know what to look for (unless it's obvious).I always remember to turn it off. Mostly cause it keeps tripping the breaker.I will take some photos and post back. It will probably take a few days, so I'd appreciate your patience.

author: helius
author_rank: Super Contributor
timestamp: October 08, 2019, 03:33:07 am
content: One thing I have noticed about electric pressure washers is that they do not like to start when the supply hose is at high pressure. This requires more torque than the motor is capable of, so it stalls. Stalled motors can trip breakers if they are not impedance protected. The solution is simply not to open the supply faucet all the way.

author: floobydust
author_rank: Super Contributor
timestamp: October 08, 2019, 03:42:42 am
content: If it blows the breaker when you stop flow (finger off the trigger), check the pressure relief valve is not clogged. Pressure washers get rust and particles in the valve body, or worse yet frozen in the garage during winter.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 08, 2019, 02:48:46 pm
content: Quote from: Hogwild on October 07, 2019, 10:57:44 pm1900W at 115V is 16.5 amps. The breaker is doing its job! You would be better off running this washer on a 20A circuit.I really don't know why anyone ever bothered making 115V/15A circuits in the first place... they are a constant nuisance as they are so easy to overload.Only the UK knows how to do this properly (240 volts, 13 amps in all standard outlets = 3,100 watts).

author: floobydust
author_rank: Super Contributor
timestamp: October 08, 2019, 09:20:28 pm
content: In North America, ampacity is based on the sockets and wire, commonly #14AWG(2.08mm^2) good for 15A/60°C. I don't know what Europe uses for 13A.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 08, 2019, 10:24:23 pm
content: The "secret sauce" in the UK (not the rest of Europe) is the use of ring circuits... allowing thinner wires to be used. Very clever idea.

author: amyk
author_rank: Super Contributor
timestamp: October 09, 2019, 11:32:30 am
content: Quote from: SilverSolder on October 08, 2019, 02:48:46 pmThat is providing the motor is designed to draw that much current, which can be confirmed once pictures of the nameplate/more specifications come to light.

author: Hogwild
author_rank: Regular Contributor
timestamp: October 09, 2019, 03:25:02 pm
content: Okay, an update....I'm swamped, so I haven't yet had time to take the thing apart and look inside. But yesterday, we needed to powerwash an area closer to the AC outlets. This time, I tried it without an extension cord. In 2 hours of power washing, the unit only blew the breaker once. That's way better than how it worked with an extension cord. So, I assume part of the problem was drawing too much current with the extension cord.BTW, I didn't previously have much choice-my house only has two outlets, one in front and one in back and they both are not close enough to where I wanted to work without an extension.I have finished all the washing work now, and will get to taking the unit apart soon.

author: james_s
author_rank: Super Contributor
timestamp: October 09, 2019, 10:02:33 pm
content: Quote from: SilverSolder on October 08, 2019, 02:48:46 pmIf only they'd had hindsight back thenYou have to look at it in the context of when the 15A 120V receptacle became standard. A typical house at that time might have had a 30A service, maybe 50A if it was fancy. There would be ceiling lights in most rooms and a few receptacles, maybe just one or two in a room where you'd plug in a lamp, maybe a radio, clock or a vacuum cleaner. 15A probably seemed generous at the time and even today it's still adequate for most things, hence the rarity of 20A 120V receptacles in residential settings. Larger loads typically use 240V, a large electric pressure washer is a bit of an edge case, it's possible that it was designed with intent of having a 20A plug on it.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 10, 2019, 03:03:37 am
content: Quote from: james_s on October 09, 2019, 10:02:33 pmMost US homes have at least one serious outlet: the Dryer Outlet! 230V, 30A blows away even the UK's awesome 240V/13A outlets! The only downside is that there is usually only one of those outlets in a house, so you need a long (and serious) extension cord...

author: beanflying
author_rank: Super Contributor
timestamp: October 10, 2019, 06:01:00 am
content: 110V @ 30A is not a defense for perpetrating a bad ideaMore Volts Less Amps please!In Oz each state varies but we can hang 15A @ 240V off the end of 2.5mm sq on a domestic circuit or like in the case of my shack a lot more with a 4mm sq run and a sub board that will handle over 30A @ 240V. What size conductor would you need on 110V and how much extra would it cost for a 40m run?

author: SilverSolder
author_rank: Super Contributor
timestamp: October 10, 2019, 12:03:50 pm
content: It was a bad decision made a long time ago... we're stuck with it, sadly! And you are right, it does use more copper for less power delivered. Most of the time it all works OK but you run into the limitations real quick if you have portable electric radiators, kettles, etc., that you try to use.US dryer outlets are actually 240V... 240V / 30A. So you get > 7KW out of one of those!I have a long 30A extension cord that I use to run a welder and /or a 5KW fan heater in the garage.

author: james_s
author_rank: Super Contributor
timestamp: October 11, 2019, 05:22:06 am
content: Quote from: SilverSolder on October 10, 2019, 03:03:37 amThose with electric cook stoves often have a 50A 240V receptacle. It's also not uncommon to have a 240V 15 or 20A receptacle out in the garage for running things like air compressors and you occasionally see those indoors for large window AC units. I've noticed a lot of people in other parts of the world seem unaware that 240V is the standard voltage feeding houses in the US, it's just fed from a center-tapped transformer giving 120V from either side to neutral. The higher voltage is available for large loads that need it. In some ways it would be handy if everything was 240V however until recently that had significant disadvantages, 240V incandescent bulbs are quite a bit less efficient than 120V for the same wattage and 240V potential to neutral is arguably quite a bit more dangerous. Every system has advantages and disadvantages.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 11, 2019, 10:14:24 am
content: Quote from: james_s on October 11, 2019, 05:22:06 amYes, the center tapped transformer is a kind of cool idea in principle. Half the outlets in the house are 180 degrees out of phase with the other half... not sure if this doesn't generate more EMI than having everything on one phase?At least it does offer an easy opportunity to generate 240V, by suitably hacked extension cords connected to outlets that are on opposite phases! (I'm pretty sure this is not approved... but it does work!).I wasn't aware that incandescent light bulbs have different efficiencies - I though they were all somewhere in the "Terrible" category?

author: beanflying
author_rank: Super Contributor
timestamp: October 11, 2019, 10:24:01 am
content: Given the fairly widespread availability of 220V in houses it is surprising there hasn't been a push to migrate over time given most of the worlds population runs 200+V in particular as most home appliances are made offshore these days.I will be good and not mention the Metric system either but it is good to see Liberia and Burma are moving toward using Metric

author: james_s
author_rank: Super Contributor
timestamp: October 11, 2019, 05:59:23 pm
content: Quote from: SilverSolder on October 11, 2019, 10:14:24 amOh they're all terrible by modern standards, but until about 15 years ago there were not a lot of really good alternatives for domestic lighting so your option was terrible efficiency or even more terrible efficiency. Even today in 2019 incandescent lamps are still everywhere in homes, and they would be even more dominant still if not for regulations to phase them out. A 240V bulb needs to have a filament that is much longer and thinner so it draws half as much current, this results in thermal losses that are much higher.Looking at a common UK 240V 100W "GLS" lamp the specs I find are 1320 lm and 13.2 lm/W. A standard USA 120V 100W "type A" incandescent lamp is 1600 lm so 16 lm/W, so almost 20% which is a pretty significant difference. There is an even greater difference with lower wattage lamps, IIRC a 240V 60W lamp is not much brighter than a 120V 40W lamp.

author: tooki
author_rank: Super Contributor
timestamp: October 11, 2019, 09:13:33 pm
content: Quote from: SilverSolder on October 08, 2019, 02:48:46 pmA device with greater than 15A rated current draw isn’t allowed to use a regular NEMA5-15 plug.The OP says “something like 1800 or 1900”, which means the device is intended to draw 15A (15A x 120V = 1800W).With that said, a breaker is NOT supposed to trip at less than 1A overcurrent!! A small overload should not trip for a long time (using the thermal part of the circuit breaker), and the overload that causes immediate trip (using the electromagnetic part of the circuit breaker) is many, many times the nominal load. (It’s a common misconception that fuses and circuit breakers are supposed to blow the instant the current rating is exceeded even a little bit.)So unless the circuit in question was already loaded with other loads, the 15A of this machine should not cause a trip at all, nor should the inrush current when it turns on.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 11, 2019, 09:39:21 pm
content: Quote from: tooki on October 11, 2019, 09:13:33 pmYou are just at the edge of the permissible 10% overload at 16.5A and, in principle, the breaker should blow after a predefined time?https://testguy.net/content/197-Characteristics-of-Circuit-Breaker-Trip-Curves-and-CoordinationI see what you mean about the device not being allowed to draw that much current. If so, it may be faulty (and the breaker is still doing its job!). There could also be other loads on the circuit.Too many unknowns error in line 6, program terminating!

author: tooki
author_rank: Super Contributor
timestamp: October 11, 2019, 10:00:35 pm
content: It’s not a 16.5A device.It’s 15A. The OP was unsure about whether it was 1800 or 1900W, but it cannot be more than 1800W nominal, or else it would have to come with a plug that doesn’t fit into a 15A receptacle. Given that the OP has tried it on multiple circuits, and that the appliance used to work just fine, it’s quite reasonable to assume that it is not simply a device that is too beefy for the circuit.Remember also that you calculated the current by dividing the watts by 115V, but that’s wrong. North America has used 120V for many, many decades now, so 120V is what you need to be dividing by. Regardless, 1900W is a 5.5% overload of an 1800W circuit: a breaker should allow that condition indefinitely.

author: james_s
author_rank: Super Contributor
timestamp: October 11, 2019, 10:21:00 pm
content: Quote from: tooki on October 11, 2019, 09:13:33 pmI think it's reasonable to assume that the circuit *is* loaded with other devices. In fact that could be why the pressure washer sometimes works and sometimes trips. Is there perhaps something like a refrigerator or freezer on the same circuit that occasionally cycles on?

author: SilverSolder
author_rank: Super Contributor
timestamp: October 12, 2019, 12:53:36 am
content: Quote from: tooki on October 11, 2019, 10:00:35 pmFair point, but it still seems to me that we would need a more accurate measurement of the specific conditions to answer the question as scientifically as you are attempting to do.For example: the long extension cord would mean a lot less than 115V arrives at the pressure washer. This could mean the motor could have trouble spinning up against the mechanical resistance of the pump to begin creating counter-EMF, and all the while it would be drawing a higher start-up current for an extended time, blowing the breaker which is already marginal for this device.The OP stated that the problem was reduced when using a shorter cord...

author: mansaxel
author_rank: Super Contributor
timestamp: October 12, 2019, 07:34:54 am
content: Quote from: beanflying on October 10, 2019, 06:01:00 am16A on 230V is quite nice.But wait! It gets better:There is no substitute for three-phase. Over 10KW from one outlet. Domestic. (Pic is from inside my garage) And that from a 5g2.5mm2cable. This particular outlet is driving a drill press (there are no capacitors in that drill press, but only the most beautiful electric motor ever designed, the three-phase induction motor) but it is actually put there in preparation for the heavy-duty stick welder I'm going to buy once I find someone wanting to part with it cheaply..

author: SilverSolder
author_rank: Super Contributor
timestamp: October 12, 2019, 03:39:00 pm
content: Quote from: mansaxel on October 12, 2019, 07:34:54 amA real Viking wall outlet! - doubles as a charge point for an e-Longboat?

author: james_s
author_rank: Super Contributor
timestamp: October 12, 2019, 06:26:56 pm
content: I've always been envious of those who can get 3 phase power at home, outside of some agricultural situations that has never really been a thing hereOf course these days I suppose it doesn't matter so much, I run 3 phase motors at home easily using a VFD, the variable speed makes that worthwhile even if I already had 3 phase power.

author: Hogwild
author_rank: Regular Contributor
timestamp: October 13, 2019, 08:17:30 pm
content: So, what's my next troubleshooting step? Measure the current at startup again with the Kill-A-Watt? Test something else?

author: james_s
author_rank: Super Contributor
timestamp: October 13, 2019, 08:52:12 pm
content: I would monitor the running current, and then figure out what else is on the same circuit. The startup surge should normally not be an issue.

author: Hogwild
author_rank: Regular Contributor
timestamp: October 13, 2019, 09:19:35 pm
content: Turns out...wait for it...my furnace may be on the same circuit.Yes, I know how idiotic that is, but I didn't design the house, and to be fair, it's a 61-year-old house, so I doubt they were anticipating stereo gear, let alone power washers. Of course, these problems could have been minimized if they'd even labelled circuits in the breaker boxes. Will do some more research and post back. I guess I may have to resort to turning off the furnace while I'm pressure washing?

author: james_s
author_rank: Super Contributor
timestamp: October 13, 2019, 09:24:18 pm
content: Or find a different circuit to connect it to. This is not really uncommon at all, what I would do is spend a couple hours to go through and determine what circuit *everything* is on and put it all in a spreadsheet then print up a list to tape in the cover of the panel. If your panel happens to be reasonably near where you use the pressure washer you could even install a dedicated receptacle on its own circuit.I have one of these that has been very handy for thishttps://www.amazon.com/Klein-Tools-ET300-Electrical-Standard/dp/B003LHJSY8Once you take the time to do this once, it saves you a lot of time in the long run.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 13, 2019, 10:17:02 pm
content: The furnace and fan uses about 10A - 12A here... and is powered via its own separate 15A circuit.Old houses can become a real spaghetti zone as new things are added, sometimes hard to anticipate by succeeding generations of electricians...The house I'm in now is only around 35 years old, and I've still had to redistribute various loads across the breakers to avoid regular breaker failures (i.e. tripping even though the load is technically OK). Whatever the specification says, if a breaker runs hot and close to its limit all the time, it eventually starts misbehaving (compared to surrounding breakers of the same make, model, and manufacturing batch that are not loaded as hard)...You can see it with an IR camera, a heavily loaded breaker lights up like a supernova in the middle of the board!

author: Hogwild
author_rank: Regular Contributor
timestamp: October 26, 2019, 06:45:40 pm
content: The suggestion of using another outlet was one I already thought of, but the closest outlets are all...you guessed it...far enough away that I need an extension cord. Maybe the addition of an extension cord will be fine on a circuit with less load. I will try that on a circuit with less load, but not likely until next spring when it's warm enough to try using the washer. I don't want to risk damaging it.Thanks everyone.

author: james_s
author_rank: Super Contributor
timestamp: October 26, 2019, 06:48:48 pm
content: An extension cord is not a problem provided it is sufficiently heavy to carry the load.Your other options are install another outlet on its own circuit, or locate and shut off any other loads on the existing circuit while you are using the pressure washer.