3 phase motor - no starter, no switch, Dangerous

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Sierrasparky

Sierrasparky

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Location
USA
Occupation
Electrician ,contractor
Last week came across a 3 phase motor with no overload protection , no start stop, no switch just turned on and off with the breaker.

The owner claimed it's been like that for years.
How do you explain that you need a motor starter as this is a dangerous situation.
 
Sierrasparky said:
Last week came across a 3 phase motor with no overload protection , no start stop, no switch just turned on and off with the breaker.

The owner claimed it's been like that for years.
How do you explain that you need a motor starter as this is a dangerous situation.
Click to expand...

You don't. You can not argue with success and as far as the owner is concerned 'if it ain't broke, don't fix it'. I suggest, but have given up otherwise for existing installs.
 
Sierrasparky said:
Last week came across a 3 phase motor with no overload protection , no start stop, no switch just turned on and off with the breaker.

The owner claimed it's been like that for years.
How do you explain that you need a motor starter as this is a dangerous situation.
Click to expand...
In what way is it dangerous in your opinion?
 
Sierrasparky said:
Last week came across a 3 phase motor with no overload protection , no start stop, no switch just turned on and off with the breaker.

The owner claimed it's been like that for years.
How do you explain that you need a motor starter as this is a dangerous situation.
Click to expand...

What size motor? While rare, it is not unheard of for a small three phase motor to have built in thermal protection.
 
No Thermal protection. Ive seen these things almost start a fire when locked up.
 
electrofelon said:
I agree. Bear with me and follow my logic: Someone who doesnt know codes, usually thusly doesnt know about the larger OCPD allowance for motors so you will often see say 12 gauge on a 20 amp. OF course you could have an extended overload just under the OCPD rating that could be hazardous.
Click to expand...
My guys used to do the panel build for the lighting division. C-curve MCBs were used for circuit protection and as a means of isolation. No other OCPD was used. I don't see why you couldn't do the same with motors if a correctly rated MCB is used.

Whenever we had to supply a fixed speed motor there was normally a requirement for a remote stop/start so there was a contactor and a thermal overload.
But some things were an exception. The heatsink cooling fans were impedance protected internally. We'd still fit fuses but that was to protect the wiring
 
iwire said:
What is 'almost start a fire', that is like 'almost pregnant'.
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c'mon, you've seen smoked wiring that didnt ignite. :D

as for almost pregnant, "almost" counts in horseshoes, hand grenades, and nuclear weapons, tho a missed period of the non-grammatical variety could cause enough concern for "almost" to count there as well. :cool:


electrofelon said:
I agree. Bear with me and follow my logic: Someone who doesnt know codes, usually thusly doesnt know about the larger OCPD allowance for motors so you will often see say 12 gauge on a 20 amp. OF course you could have an extended overload just under the OCPD rating that could be hazardous.
Click to expand...

I think you meant 30A+.

~~~~~~~~~~~~~~~~~~~~

Some owners will have to learn the hard way, like when they smoke the motor, wiring, or breaker on a holiday weekend. Then the "I told you so" comes with a triple-time emergency rate bill.
 
Is it a code violation violation? If so as a professional did you explain why? Who ever authorized the installation either didn't have a clue what was required either going with a handyman that claims that they knew what they were doing or went with the cheepest price as providing correct motor protection doesn't come cheep.
Any noncompliant installation may work forever without incident but without providing adaquate protection there is an issue should a failure occur. A good example is a simple replacement breaker purchased from a second hand market which has never been retested and certified for factory calibration that may turn on and off just fine but will not automatically trip if it actually was require to protect?

I'm sure that the insurance company would raise this issue should there be a claim for loss filed against them.
 
Ok is a standard breaker rated to switch a motor on and off? ( by standard I mean your every day plug in)
Does SWD rating cover Motor starting?
 
templdl said:
Is it a code violation violation? If so as a professional did you explain why? Who ever authorized the installation either didn't have a clue what was required either going with a handyman that claims that they knew what they were doing or went with the cheepest price as providing correct motor protection doesn't come cheep.
Any noncompliant installation may work forever without incident but without providing adaquate protection there is an issue should a failure occur. A good example is a simple replacement breaker purchased from a second hand market which has never been retested and certified for factory calibration that may turn on and off just fine but will not automatically trip if it actually was require to protect?

I'm sure that the insurance company would raise this issue should there be a claim for loss filed against them.
Click to expand...
Most of the time the only loss is the motor. Maybe depending on details there is secondary loss of product being handled by the motor, though those losses could occur if a proper motor overload shuts the process down as well.

If it is a 10 HP or less motor the loss of the motor usually isn't an insurance issue - it probably doesn't even exceed any deductibles that need paid before coverage kicks in.

I'm not advocating that we shouldn't provide overload protection, after all there is a lot of protection installed but mis-applied and motors burn out anyway. Also is a lot of protection properly installed at first, then a user got tired of it cutting out and cranked up the setting, bypassed it, etc., then they ask what caused the motor to burn out.
 
Across the line

Across the line

Sierrasparky said:
Last week came across a 3 phase motor with no overload protection , no start stop, no switch just turned on and off with the breaker.

The owner claimed it's been like that for years.
How do you explain that you need a motor starter as this is a dangerous situation.
Click to expand...


Besides the heaters
When utility power is interrupted, that motor will kick back on without being asked to
 
Sierrasparky said:
Ok is a standard breaker rated to switch a motor on and off? ( by standard I mean your every day plug in)
Does SWD rating cover Motor starting?
Click to expand...

Using a breaker as a switch (for anything) is one of the poorer practices I have seen. But lighting contactors, photocells, motor starters, etc. fail and they are bypassed and the breaker gets used that way. Not saying it's right but if they couldnt handle it, I'd be working 80 hour weeks just replacing breakers.
 
templdl said:
Is it a code violation violation? If so as a professional did you explain why? Who ever authorized the installation either didn't have a clue what was required either going with a handyman that claims that they knew what they were doing or went with the cheepest price as providing correct motor protection doesn't come cheep.
Any noncompliant installation may work forever without incident but without providing adaquate protection there is an issue should a failure occur. A good example is a simple replacement breaker purchased from a second hand market which has never been retested and certified for factory calibration that may turn on and off just fine but will not automatically trip if it actually was require to protect?

I'm sure that the insurance company would raise this issue should there be a claim for loss filed against them.
Click to expand...

disco has to be within sight of the machine
 
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