5HP is not so much 1HP = 750 W so 5 HP = 3.75Kw ..........10 HP = 7.5Kw

This instant domestic water heater is 8.5Kw installed in many UK homes for showers ... single phase ...An electric cooker will take more power ...

I would try one pump first , if not enough you can always get another ..

That is not the way it works. Yes, 1.0 HP = 746 watts which is fine on paper. Put your hand on a running motor, do you feel heat? That is loss. Does a running motor have friction? That is lost. My numbers were pretty close to on target as were Max's numbers. While 746 watts = 1.0 HP that would be in a world without any loss. My 4.0 KW generator uses an 8.0 HP engine, now why is that? I suggest you do a little research to understand how motors and generators actually work with a focus on efficiency as that is the key word.

Ron

 

The OP is located in UK, why mention US??
As I already mentioned, in some older jurisdictions the service Co. does not like the unbalance of the supply transformer, a long time ago, but these may still exist.
BTW, N.A. is also 240v residential as well as 120v!
Max.

Sometimes there is a need to read the thread before jumping in. I guess it also helps to understand the efficiency of an electric motor.

Ron

 

Over in the UK men are men ...fearless ....240V running around our houses , so we only need half the current the US does for the same power ...
TS lives in the UK

Gee, I have 240 VAC running around my house and I am in the US. We use 240 V for plenty of residential things here, same as Canada. Do you realize it helps to read and actually comprehend an entire thread?

Ron

 

It reminds me of when I was doing my UK apprenticeship and at that time there were a few USAF bases close by, and they occupied quite a few off-base (local) housing.
The families brought over all their appliance as as well as the 'huge' automobiles from the US, keep in mind England's narrow roads at that time.'
We had to accommodate all the power hungry US appliances such as stoves and dryers etc.
Incidentally, the fridge I had in UK at that time was smaller than the freezer at the top of one of the US fridge's!
One US friend introduced me to Jim Beam, I have been looking for him ever since.
Max.

 

The families brought over all their appliance as as well as the 'huge' automobiles from the US, keep in mind England's narrow roads at that time.'
We had to accommodate all the power hungry US appliances such as stoves and dryers etc.

Yeah, I have seen that. When they ship "household goods" they ship it all. When I was it Italy a young couple split up. Navy kid and his wife. I bought a frost free 18 cubic foot refrigerator with freezer for like $100. Ran it on a transformer at 50 Hz and it actually ran fine for me over 3 years. I never bothered shipping household goods but we could have. I bought a car over there for a few bucks and sold it when we left. I was not US military but worked as a civilian for the US DoD. It was amazing the stuff people dragged over there as well as Europe in general.

Ron

 

Incidentally when I came to Canada, I rented my UK house out to the US base housing officer for 3 years!
He also had to get used to the steering wheel on the 'wrong' side on his Chevy, as most did!
Max,

 

That is not the way it works. Yes, 1.0 HP = 746 watts which is fine on paper. Put your hand on a running motor, do you feel heat? That is loss. Does a running motor have friction? That is lost. My numbers were pretty close to on target as were Max's numbers. While 746 watts = 1.0 HP that would be in a world without any loss. My 4.0 KW generator uses an 8.0 HP engine, now why is that? I suggest you do a little research to understand how motors and generators actually work with a focus on efficiency as that is the key word.

Ron

My experience with electric water pumps is that manufacturers use 750W=1HP ....

Here is a chart from a spa pump manufacturer ..... You can see from the second line this manufacturer does just that for 2 and 4 HP pumps giving 1.5KW and 3 KW ...for the 5HP they give 3.8Kw .... , almost certainly electrical power consumption is accurate as this is easily checked , and could blow fuses if greater than listed ... the manufacturer has given HP figure as the electrical input and not shaft output ....

If our thread starter has bought his 5HP pumps from this manufacturer they will only consume 3.8KW each .

 

5HP is not so much 1HP = 750 W so 5 HP = 3.75Kw ..........10 HP = 7.5Kw

This instant domestic water heater is 8.5Kw installed in many UK homes for showers ... single phase ...An electric cooker will take more power ...

I would try one pump first , if not enough you can always get another ..

This electric shower is even 10.5 kw which is equivalent to 14 hp. Great ! I can now go ahead with no fear of failure. I contacted the pool guy. He said two 5 hp pump is best.

 

It's 4Amps per KW on UK mains, so 5Hp is approx 3.7KW, that's a 16Amp supply, are your motors single or 3 phase?

 

This electric shower is even 10.5 kw which is equivalent to 14 hp. Great ! I can now go ahead with no fear of failure. I contacted the pool guy. He said two 5 hp pump is best.

You started with two 5.0 HP pumps and now I see a heated shower head. What exactly are you planning to do? Do you have any data sheets?

Next, while I agree 1.0 HP = 746 Watts of power that assumes a 100% efficient motor and I have never seen a 100% motor.

Ron

 

You started with two 5.0 HP pumps and now I see a heated shower head. What exactly are you planning to do? Do you have any data sheets?

Next, while I agree 1.0 HP = 746 Watts of power that assumes a 100% efficient motor and I have never seen a 100% motor.

Ron

Still using the two pumps at 5 hp each.
The electric heater was an example to show if one can fit electric water heater which requires 10.5 kw in a home then two pumps requiring 4 kw each should be no problem.

 

Still using the two pumps at 5 hp each.
The electric heater was an example to show if one can fit electric water heater which requires 10.5 kw in a home then two pumps requiring 4 kw each should be no problem.

Like i said earlier, UK mains is 4Amps per KW, so for you that's 32Amps minimum.

 

Still using the two pumps at 5 hp each.
The electric heater was an example to show if one can fit electric water heater which requires 10.5 kw in a home then two pumps requiring 4 kw each should be no problem.

OK, my point through all of this is I suggest before you buy your pumps look at their specifications. The pump motors will have a FLA (Full Load Amps) rating. While 746 watts does equal 1.0 HP and in theory then 5 times 746 watts would equal 5.0 HP or 3730 watts which at 220 volts would be 16.95 amps all of that assumes your pump motors are 100% efficient. They are not as no motor or generator is 100% efficient. Efficiency is about what you put in verse what you get out.

A typical off the shelf 5.0 HP motor, a motor considered efficient will be about 83% efficient. The full load amps at 230 volts will be about 19.5 amps. So 230 * 19.5 = 4.485 KW when we consider motor efficiency give or take a little. That is an 83% efficient pump motor and actually that is pretty good as far as a motor goes. So with allowing a margin of power if at 230 volts a 5.0 HP pump motor draws about 20 amps I would allow for about 25 amp service per pump line at 230 volts. I would also have the service installed by a competent electrician. Additionally you may want to consider that a 5.0 HP pump motor is normally started and stopped using a motor control contactor capable of switching the required current and voltage for the motor. They are normally chosen based on the motor HP rating. A good control contactor includes overload control (normally a heater switch).

So anyway if you have 220/230 volt service with the current to drive 10 HP total in motors then have at it.

Ron

 

OK, my point through all of this is I suggest before you buy your pumps look at their specifications. The pump motors will have a FLA (Full Load Amps) rating. While 746 watts does equal 1.0 HP and in theory then 5 times 746 watts would equal 5.0 HP or 3730 watts which at 220 volts would be 16.95 amps all of that assumes your pump motors are 100% efficient. They are not as no motor or generator is 100% efficient.

It just means the manufacturer has stretched the truth a bit ... just as LED light manufacturers do when calling a bulb 80W when it consumes 15W of electricity ....they mean it's equivalent to an 80W incandescence bulb.

The motor does not put out 5HP . it just consumes 5HP of electricity ... ( that is correct terminology , HP is a measure of power directly convertible to watts) ... the motor probably puts out about 4HP ..... and the pump probably puts out around 2HP (this will vary with head)..

How do you measure the power output of the pump? .... By how much water it can pump to a given height every second ...mgh

A pump outputting 1Kw of power can pump 100 Kg of water to a height of 1 meter in Earths gravity every second.

 

The motor does not put out 5HP . it just consumes 5HP of electricity ... ( that is correct terminology , HP is a measure of power directly convertible to watts) ... the motor probably puts out about 4HP ..... and the pump probably puts out around 2HP (this will vary with head)..

Yes, and when a motor consumes about 5 HP of electricity (5 HP * 746 Watts) and delivers 4 HP on the shaft (4 HP * 746 Watts) I guess we could say it was 80% efficient. The example I used earlier was a 5 HP 230 Volt motor with the motor able to output 5 HP shaft and the current it used to do that included loss. If I look at power out verse power in I get the efficiency. Anyway it all comes down to how it's rated and the name plate data or a data sheet should contain the actual numbers.

Ron

 

The starting current of a single phase motor will be many times the full load current. I think the starting current of the motors is likely to cause a problem.

Les.

 

The starting current of a single phase motor will be many times the full load current.
Les.

Just as a 3ph also is.
Max.

 

I agree but at least with a three phase motor you could reduce it using a star delta starter.

Les.

 

True, as long as all the coil ends are brought out.
Max.

 

I was thinking of using single phase vfd ( variable frequency drive) one for each pump to control the pumps' speed.