Pressure washer keeps tripping breaker

[Hogwild]

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?

[SparkyFX]

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?

[Hogwild]

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.

[Gregg]

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 ground
2.  The pump side could have mineral deposits from hard water causing excessive load on the motor
3.  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 seals
5.  Pump valves may be sticking
6.  The circuit breaker may be “tired” from tripping too many times
7.  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?

[Hogwild]

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.

[Gregg]

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

[Hogwild]

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.

[TheMG]

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.

[james_s]

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.

[Hogwild]

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.

[james_s]

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.

[Hogwild]

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?

[beanflying]

'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.

[amyk]

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.)

[Tom45]

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.

[Hogwild]

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.

[helius]

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.

[floobydust]

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.

[SilverSolder]

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.

1900W 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).

[floobydust]

In North America, ampacity is based on the sockets and wire, commonly #14 AWG (2.08mm^2) good for 15A/60°C. I don't know what Europe uses for 13A.

[SilverSolder]

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.

[amyk]

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.

1900W at 115V is 16.5 amps.   The breaker is doing its job!   You would be better off running this washer on a 20A circuit.

That 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.

[Hogwild]

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.

[james_s]

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.

If only they'd had hindsight back then

You 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.

[SilverSolder]

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.

If only they'd had hindsight back then

You 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.

Most 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...