[nmackintosh]

Hey guys. I have a single phase 240v 2HP motor so the FLA is 12A as per Table 45. It has no problem starting on a 2 pole 15a circuit breaker but I need overload protection according to rule 28-308 (a) because its more than 1 HP. I am just having a hard time explaining to the customer why they need the overload protection when the breaker is only 15a. I could understand needing it if I had to put in a larger breaker for the inrush current but its ok on a 15 amp. I was reading about the breakers inverse time characteristics so if it had a small overload the breaker wouldn't trip and that would damage the motor? Any help would be great. Thanks.

 

[wildleg]

does the motor have internal protection ?

 

[FrunkSlammer]

Doesn't the code rule you cited say you don't need it?

 

[nmackintosh]

does the motor have internal protection ?

Not thermally protected

 

[nmackintosh]

Doesn't the code rule you cited say you don't need it?

I dont think so. Even tho its protected by a 15a breaker its still over 1 hp

 

[FrunkSlammer]

Not thermally protected

What about ZP? Impedance protected?

Looked up the rule and you're right, just 1hp or less. That's pretty ridiculous. Wish I had more to offer, I would just install it.. but if you're worried about an inspector, ya gotta do what ya gotta do.

 

[347sparky]

The 15a breaker does not mean anything in terms of overload protection. Overloads/heaters protect the motor. I've had small motors protected by overloads with a .9a trip setting. Tell your customer overloads and the breaker do two different jobs.

 

[greenman]

Hey guys. I have a single phase 240v 2HP motor so the FLA is 12A as per Table 45. It has no problem starting on a 2 pole 15a circuit breaker but I need overload protection according to rule 28-308 (a) because its more than 1 HP. I am just having a hard time explaining to the customer why they need the overload protection when the breaker is only 15a. I could understand needing it if I had to put in a larger breaker for the inrush current but its ok on a 15 amp. I was reading about the breakers inverse time characteristics so if it had a small overload the breaker wouldn't trip and that would damage the motor? Any help would be great. Thanks.

Just tell him that with out it, it could become one big heater and cach on fire. "If it faults out". It may not trip the breaker.

 

[union347sparky]

The 15a breaker does not mean anything in terms of overload protection. Overloads/heaters protect the motor. I've had small motors protected by overloads with a .9a trip setting. Tell your customer overloads and the breaker do two different jobs.

Also known as "tell your customer stop being so cheap and let me do my job for your best interest"

If only we could say that.

 

[nmackintosh]

Just tell him that with out it, it could become one big heater and cach on fire. "If it faults out". It may not trip the breaker.

I guess a regular 2 pole 15a siemens breaker is thermal magnetic so it does have some thermal properties. Just wondering if its enough. The customer is a friend so I don't wanna sell a bunch of stuff he doesn't need... or maybe I do... haha

 

[ponyboy]

I guess a regular 2 pole 15a siemens breaker is thermal magnetic so it does have some thermal properties. Just wondering if its enough. The customer is a friend so I don't wanna sell a bunch of stuff he doesn't need... or maybe I do... haha

No it's not enough. It's a code rule, and a basic one at that. I don't think you'd be selling him stuff he doesn't need, you'd just be doing your job, correctly.

 

[l0sts0ul]

Every breaker and time delay fuse has thermal properties but you're looking at it the wrong way.

Use overloads and a manual starter. I personally have spent time repairing installs where a breaker only was used as OVERLOAD protection and the problem cost the customer thousands up front and even more in tenants that moved out because they got tire of not having runnin hot water on the 12th floor.

Don't be cheap or don't do the job. Do it properly.

 

[nmackintosh]

Every breaker and time delay fuse has thermal properties but you're looking at it the wrong way.

Use overloads and a manual starter. I personally have spent time repairing installs where a breaker only was used as OVERLOAD protection and the problem cost the customer thousands up front and even more in tenants that moved out because they got tire of not having runnin hot water on the 12th floor.

Don't be cheap or don't do the job. Do it properly.

Thanks for the info. Yes after some research I agree that it is needed. Just had to get it straight in my head. Thanks guys.

 

[oliquir]

i would use a manual starter/overload combo, they sell for about 40-50$ or just an overload for about 25$

 

[Mike_586]

i would use a manual starter/overload combo, they sell for about 40-50$ or just an overload for about 25$

I'd do the same.

 

[JRaef]

I guess a regular 2 pole 15a siemens breaker is thermal magnetic so it does have some thermal properties. Just wondering if its enough. The customer is a friend so I don't wanna sell a bunch of stuff he doesn't need... or maybe I do... haha

Can't speak for the CEC, but in our NEC, you technically CAN use fuses as the overload Protection, if, and ONLY if, the fuse rating happens to hit the EXACT point necessary to provide motor running over load protection as defined in that section. That almost NEVER happens.

In this specific case, where the FLC is 12A and the protection point must be 15A (125%), then it just so happens to work. But that is only if the motor is marked as having a 1.15 Service Factor or is rated for greater than 40degC operation. If not, then the maximum is 115% and you would need 13.8A fuses (which you will not find).

But there is no allowance for using Branch Circuit Breakers as motor OL protection, because the trip curves for the breakers are not really designed for that purpose. So we use the word "separate" in the NEC when it comes of overload protection, meaning that the motor thermal OL protection must be SEPARATE from the branch circuit protection. I'd be willing to bet that the CEC is worded very similarly. You have to pay close attention to ALL of the words.

 

[bjaenen]

The way I always looked at it is a breaker or fuse when used with motors is used for OCP... a short circuit or failure of the windings.. the Overload does exactly what it sounds like if you over work its capabilities the overload protects the windings and wire feeding the motor.

 

[Navyguy]

I wish there was a toggle style manual starter that was rated for 2 HP and below. The typical one is a fractional HP manual starter with a single OL in it and max rating is 1HP.

Now the OP has to put in a Size 0 (probably 2 pole) starter because it is 2 HP. Not saying that he shouldn't, just saying that I wish there were some other options for something like this.

Having said that, the cost of a properly installed set of OLs is well worth the cost of letting the magic smoke of the motor out.

Cheers

John Kuehnl-Cadwell