GFI Protection on 480V, 1ph, 5kW space heater

[edienberg]

I am installing a 480V, single phase, 5kW space heater in a "hot box" around an above ground backflow. Do I need to feed this heater with a 2 pole, 480V, GFI breaker?

 

[rbulsara]

NO. But if you choose to, it should be less sensitive (30mA sensitivity) breaker desgined for equipment protection and not personnel protection.

 

[Skogsgurra]

The 30 mA is for life saving. I think the second "0" dropped. Was probably meant to be 300 mA.

But I would use 30 mA. If using any at all.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[davidbeach]

Skogs, On this side of the pond, 5mA is personnel protection and 30mA is equipment protection for things like heat tracing. The 5mA is [±]1mA and anything over 6mA is not considered suitable for personnel protection. On the other hand, these are generally applied at the receptacle (outlet) and occasionally at the breaker; applying it at the breaker allows the natural leakage of the circuit to "pre-load" the GFCI with anywhere up to enough to cause a trip. The 30mA devices are almost always breakers.

 

[ScottyUK]

Interesting - over here a 10mA RCD is used in higher risk environments and a 30mA RCD is the standard for personnel protection. 100mA is about the lowest used for equipment protection but there are quite a few variations of tripping current and response time, e.g. 100mA / 100ms is frequently used for equipment protection and is intended to grade with a downstream 30mA instantaneous RCD used for personnel protection.


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[rbulsara]

I meant 30 mA as it is common for equipment GFP here in the USA. Personnel protection sensitivity is 4-6mA by Code as davidbeach pointed out.

I believe 300mA GFP are available. It all depends on normal "leakage" or capacitive current of the equipment and circuit. You want to beat that.

 

[Skogsgurra]

Hmm.. Very interesting.

We have a big problem with 30 mA RCDs (as we call them) and nuisance tripping. Especially when there are VFDs involved. It may be because we have a higher voltage (230 V phase-ground). I think that our RCDs are specified somewhat like Must Trip > 30 mA and Must Not Trip < 18 mA.

I have been "saved" by 30 mA devices several times - I trust them too much.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Skogsgurra]

I noticed, too late, that you actually have a 480 V installation. That's a lot for a 30 mA RCD.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...