Motor Starter for control of 3-phase process heater

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nhee2

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A customer wants to use a spare MCC bucket to control an on-off resistive process heater at their plant.

I've said it would only be possible if they replaced the MCP breaker in the bucket with a new thermal-mag breaker, as MCPs are only allowed for motor circuits. However in looking at article 430, I only see that MCP needs to be part of a listed motor controller - but not that the motor controller has to be feeding a motor.

Is there somewhere in the NEC that would allow a standard starter with MCP and OL relay to feed a non-motor load that I am missing? (customer is not in agreement).
 
nhee2 said:
A customer wants to use a spare MCC bucket to control an on-off resistive process heater at their plant.

I've said it would only be possible if they replaced the MCP breaker in the bucket with a new thermal-mag breaker, as MCPs are only allowed for motor circuits. However in looking at article 430, I only see that MCP needs to be part of a listed motor controller - but not that the motor controller has to be feeding a motor.

Is there somewhere in the NEC that would allow a standard starter with MCP and OL relay to feed a non-motor load that I am missing? (customer is not in agreement).
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The overload relay of the starter provides the thermal/over current protection while the MCP provides the short circuit and ground fault protection.

Look at 240.09.
 
jim dungar said:
The overload relay of the starter provides the thermal/over current protection while the MCP provides the short circuit and ground fault protection.

Look at 240.09.
Click to expand...
Ok. So that allows the OL to provide the branch circuit overcurrent protection if protected by an MCP in accordance with 430.52.

But all discussion in 430.52(C)(3) (for instantaneous trip circuit breaker) is written in the context of motor protection. Are you suggesting that as long as it is a listed combination starter, it can be used to protect non-motor loads (if sized/set correctly)?
 
nhee2 said:
Ok. So that allows the OL to provide the branch circuit overcurrent protection if protected by an MCP in accordance with 430.52.

But all discussion in 430.52(C)(3) (for instantaneous trip circuit breaker) is written in the context of motor protection. Are you suggesting that as long as it is a listed combination starter, it can be used to protect non-motor loads (if sized/set correctly)?
Click to expand...
My reading is that 240.09 prevents thermal only devices from protecting conductors except for those used for motor circuits.
 
How about removing the overload block from contactor to make some room in the bucket. Then install a fuse block and install fuses to provide overcurrent and additional short circuit protection. Maybe look at class fuses if space is at a premium.
 
I was on a job many years ago where the buyer bought starters instead of lighting contactors, he ordered the largest heaters that would fit to cover his mistake. A couple caught on fire because the OL contact block was bypassed!
 
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