# Modification 1Hp to 2Hp



## MikeFL (Apr 16, 2016)

@Rookie101 please fill out your profile so we know who we're talking to.
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Thanks for your understanding.


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## Wardenclyffe (Jan 11, 2019)

What's the FLA?


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## Rookie101 (3 mo ago)

Wardenclyffe said:


> What's the FLA?


15A


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## micromind (Aug 11, 2007)

For a 2HP 240 single phase motor, I would use 20 amp breakers for each motor, and a 40 for the main. 

What's the feeder wire size? 10 would be the code minimum.


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## CAUSA (Apr 3, 2013)

1- conductors are they the right size for the change?

2-follow the CEC 22.2 section 28 for motors.

Micromind has a good suggestion.

check for any standata changes for your application for your area.


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## gpop (May 14, 2018)

Rookie101 said:


> The pump spec says to put a 30A breaker for each pump unit.
> Knowing that the 30A breaker is already too high (normal 2 HP motor) how much should the main breaker be ?


If the motor has overload protection or thermal protection built in then why is 30A to high. As its a single phase 2hp grinder pump i would rather go large than being called out every time it starts with a rag in the cutter. 

30A breakers on the motors with a 50 amp main.

spec says : 2HP, heavy-duty motor - oil filled, *thermally protected *Advanced V-Slice *cutting* system (in other words a bitch to start)


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## Rookie101 (3 mo ago)

micromind said:


> For a 2HP 240 single phase motor, I would use 20 amp breakers for each motor, and a 40 for the main.
> 
> What's the feeder wire size? 10 would be the code minimum.


That's what I think too, but we're it bugs me is that the pumps builder says to put 30A breaker.


micromind said:


> For a 2HP 240 single phase motor, I would use 20 amp breakers for each motor, and a 40 for the main.
> 
> What's the feeder wire size? 10 would be the code minimum.


I got 14Ga right now, so for sure that has to go. 
For the main, if I go over 40A, I'll have to re-wire the whole thing.


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## paulengr (Oct 8, 2017)

This sounds way off. 60 A??? No way.

FLA chart for 230 V 2 HP single phase is 12 A. At 250% that’s 30 A. If you put 2 motors on it that’s a multi motor setup so we do 100% of the second motor is 42 A max so closest standard size is 40 A. The 250% rule is a max so you can’t choose next size up.

Ampacity is 15 A for 1, 30 A for 2, so #14 for one at 75 C, #10 for two.

If the starter has short circuit protection then you design for the starter as a load.


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## wiz1997 (Mar 30, 2021)

micromind said:


> For a 2HP 240 single phase motor, I would use 20 amp breakers for each motor, and a 40 for the main.
> 
> What's the feeder wire size? 10 would be the code minimum.


You might want to consider the purpose of these pumps.

These pumps are grinder pumps, they are used where the material to be pumped (lumpy sludge) must be ground up prior to moving into the centrifugal part of the pump.

These pumps are often started from a dead stop with the sludge already in contact with the grinder blades.

These pumps will easily pull more amps (of course all motors pull higher amps at start up) than normal to get the sludge moving.

I suggest going with the manufacturer's recommendation of the 30 amp breaker, otherwise you'll be experiencing a lot of tripping.

The main breaker should be no less than the rating of the largest BREAKER (30A) plus the FLA of the other MOTOR (15A), so the main breaker should have a MINIMUM 45A rating. This calculation comes from the NEC.

That's for just the motors, any other loads will also need to be added in, (control transformers, pilot lights, panel heaters, ect) so bump it to a 50A or better yet to a 60A like the manufacturer recommends. (60A might be easier to locate anyway)

Would you rather go with the manufacturer's recommendation, have no problems, be the hero or have nothing but problems and be the zero?

When there are problems with what you did, because you think you know better than the manufacturer.

Are you ready to defend your choices?

Were I work now and just about every place I've worked in the past, "I wanted to do it cheap", won't fly as a reason, when now the job has to be done again.

Costing more time and more money.

Why is rewiring the panel a problem?

Pull three breakers, install three breakers, replace a few feet of wire. (excluding the wires to the pumps.)

You have to replace the wiring to the motor any way.

They do pay you by the hour, correct?

While others are pulling wire to the pumps, the panel work can be done.

Plan your work to have at least one pump completely ready to run as soon as possible, so there is no pressure to get the second one completed.

You never mentioned the wire size of the feeder to the panel itself.

Feeder calculation:

FLA of the largest motor times 1.25 + FLA of second motor = feeder wire size

(15 x 1.25) + 15 = 33.75A 

If the pumps are short time, intermediate, periodic or varying duty the rating can be derated.

33.75 x .85 = 28.6875A

So a #10 feeder to the panel.

FYI: Motors are completely different animals that don't follow normal code, which is why motors have a code section to themselves.


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## paulengr (Oct 8, 2017)

wiz1997 said:


> You might want to consider the purpose of these pumps.
> 
> These pumps are grinder pumps, they are used where the material to be pumped (lumpy sludge) must be ground up prior to moving into the centrifugal part of the pump.
> 
> ...


Uhh be careful about the grinder pump claims here. Look at this chart:
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This looks like a NEMA B or C curve. So at starting the motor pulls locked rotor current REGARDLESS of what the load is. This current stats nearly constant until we get up around 75-80% of full speed. Then it quickly drops as the motor reaches full speed. What changes is how quickly it reaches this point. We can easily get a torque vs speed chart for any motor. At starting every bit of torque not used to just keep the motor at speed is accelerating torque. So a grinder pump just increases the amount of searchin


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