Next size larger breaker?

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ritelec

ritelec

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Jersey
Hi all.
To feed a 2.5 hp motor (I will have to look at the chart for amperage but)
The motor reads 4.5 amps at 220v

At 250% is max oc protection of 11.25 amps.

Does the next size higher at 15 amp apply to this or do I have to protect it at 10.


Thank you
 
ritelec said:
Hi all.
To feed a 2.5 hp motor (I will have to look at the chart for amperage but)
The motor reads 4.5 amps at 220v

At 250% is max oc protection of 11.25 amps.

Does the next size higher at 15 amp apply to this or do I have to protect it at 10.


Thank you
Click to expand...
You can't (easily) feed it with anything other than 14ga wire, so 15A is fine. The motor overload protection is supposed to protect the motor for actual running load amps, if the motor has no overload protection built-in, then you will need an external OL relay.
 
Thank you. Yes it's tp.

Reading about its short circuit ground fault protection at the 250% it says no more than.
It doesn't say anything about an exemption.


Dang pools. :- )

3 motors.

A 1.5 hp that reads at 220v is 4.5
1.1 hp that reads at 230v is 5.1
1.65 hp that reads at 230v is 10



The 1.65 actually reads 1.5 hp sf 1.1 total hp 1.65

Why such a large difference between the two 1.5 hp motors?

So instead of using two 15 amp gfci breakers
And a 20 amp gfci breaker ( 3 total)
I'm hoping to use 1-15 amp or 20 for the two. And one 20 amp for the largest ( 2 total)

But even if one breaker per motor is the 15 too large?
 
ritelec said:
Thank you. Yes it's tp.

Reading about its short circuit ground fault protection at the 250% it says no more than.
It doesn't say anything about an exemption.


Dang pools. :- )

3 motors.

A 1.5 hp that reads at 220v is 4.5
1.1 hp that reads at 230v is 5.1
1.65 hp that reads at 230v is 10



The 1.65 actually reads 1.5 hp sf 1.1 total hp 1.65

Why such a large difference between the two 1.5 hp motors?

So instead of using two 15 amp gfci breakers
And a 20 amp gfci breaker ( 3 total)
I'm hoping to use 1-15 amp or 20 for the two. And one 20 amp for the largest ( 2 total)

But even if one breaker per motor is the 15 too large?
Click to expand...
Are you sure the first two are not 3 phase motors? Those values are WAY low for that voltage class single phase motors. There are always differences in efficiency that show up as differences in FLC, but that is way beyond that. Those first two values are down in the 1/2HP range for single phase motors... Maybe it's not "2-1/2HP" as in "2.5HP" but rather "2 x 1/2HP".

But as to using one breaker for the whole circuit, different rules. Now you move on to 430.53.
 
Last edited:
Jraef said:
Are you sure the first two are not 3 phase motors? Those values are WAY low for that voltage class single phase motors. There are always differences in efficiency that show up as differences in FLC, but that is way beyond that. Those first two values are down in the 1/2HP range for single phase motors... .
Click to expand...

LOL
What's up with that? I see too.
 
ritelec said:
LOL
What's up with that? I see too.
Click to expand...
It's probably one of those marketing issues with regard to "HP". They can get away with it because they are really only REQUIRED to list the amps and volts, HP is not strictly defined so it's something that can be interpreted. So in the retail business they often use the concept of "develops" a certain HP as their interpretation. What that means is that under Break Down Torque conditions, the PEAK torque, which is 200-220% of Full Load Torque, when factored into the slip speed it takes to get there, can be expressed as a "developed" HP capability, however momentary that can be maintained. It's total BS and would NEVER fly in the industrial world, but there is nothing saying they can't say it, so they do, knowing that the vast majority of retail consumers will have no clue.
 
ritelec said:
OK.

So now do I rate the circuit for the HP or the amperage?

LOL
Click to expand...
From a protective device standpoint, you use the nameplate amperes info and 430.52 (or 53) rules. From a conductor sizing standpoint, you must use the HP ratings... but in this case you are going to end up at 14ga for each individual motor anyway.
 
Stupid cover

Stupid cover

Question, maybe I'm hallucinating.
But, did I read somewhere that a switch used as a controller, instead of the hp rating could be used if its rating was twice that of the load.

I installed a HP (like 10, 3 pole that the supplier had) motor switch for the blower motor in a two gang plastic box with pool light switch.

You physically have to work the motor switch to turn it on and off. It really beats up the plastic two gang enclosed cover I installed.

I will look for a different cover, but I vaguely remember this twice the amperage rating, and I figured I could get a general or heavy duty 277v 20a switch which will turn on and off with out having to be so aggressive.
I did look at the supply house and was going to get that 277 v 2 pole switch, but their book of the manufacturers specs mentioned nothing of HP rated.

Thank you.
 
1.1 hp is not a standard size listed in any of the NEC tables... you have to use nameplate amps for non standard motors.
 
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