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Need to troubleshoot

Need to troubleshoot

Need to troubleshoot

(OP)
Hi all,

This is the scenario

We have Ice boxes(Ice King) which have ICE in them which our guys use for cooling thier water and gatorade. They have compressors inside them.

These Ice boxes are connected through GFCI's. Now, we had problems with these Ice boxes, they would trip and all the ice would melt. When the vendor came, he said that all the call out he had was a trip because of the GFCI's and advised to remove them.

These problems usually happent after a storm or lightning. These boxes are grounded properly.

What could be the possible reasons for the GFCI's to trip. Are they supposed to trip during lighting or storm. Isnt it the ground wire which has to discharge the lighting voltage through it to ground. Why the GFCI operates.

Any inputs and suggestions are welcomed.

Thanks in advance.

gokul

RE: Need to troubleshoot

1) Compressors are notoriously "leaky" motors. When the "leaks" exceed the standard GFI trip level you'll get trips.

2) Lightning could easily trip a GFI with outdoor loads.


I'd get someone who understands this to actually measure the leakage current from your individual coolers.  If it's close to the GFI rating, (5mA I believe), you could see about re-distributing the coolers.

Example: Coolers are found to leak about 2.2mA.  Two are plugged into one outlet.
2.2mA x 2 = 4.4mA.

Add wet ground, wet boxes, high humidity, and perhaps some lightning induced currents and "pop".

Solution: Put in separate GFI outlets for use by each cooler.  

Keith Cress
kcress - http://www.flaminsystems.com

RE: Need to troubleshoot

My outdoor duplex outlets are GFI protected and tend to trip the GFI's when it rains from current leakage due to dirt, spider webs, insect wings, mud daubers and whatnot that get in around and through the cheap gaskets that don't seal the outlets from water or insect intrusion.   Everything's fine until it rains, then the path for conduction leakage is made and the GFI's trip ! !

About every 4 or 5 years I replace the gasketed door covers and the duplex outlets because it's easier to replace the outlet than it is to clean it and the GFI's don't trip for a year or two until the cheapo gaskets decay and rot.

Dan

RE: Need to troubleshoot

Firstly, for permanently connected equipment GFCI are not required by NEC. (unless something changed recently in code)

If you do provide them, you need to use Equipment GFCI breakers which are less sensitive, tripping at 30ma vs. 4-6ma at which the personnel GFCI breakers or outlets trip, for the reasons Keith mentioned above.

Remember 30ma devices are not intended to and will not protect human beings.

Rafiq Bulsara
http://www.srengineersct.com

RE: Need to troubleshoot

"Remember 30ma devices are not intended to and will not protect human beings."

Yet that is precisely the purpose they are used for in Europe, with 10mA types being reserved for areas of increased risk such as very wet environments. Possibly the higher voltage over here plays a part in the selection of current: the leakage currents through cable capacitance and filter capacitances are roughly double those at 120V.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Need to troubleshoot

And still, do not try to use 30 mA RCDs if you have VFDs. The capacitance in filters, cables and motors easily makes leakage currents go up to 100 mA and above. That's why there are also 300 mA RCDs (or GFCIs). Not so sure why this practice is allowed. Necessity, probably. But 300 mA kills easily. Safety with 300 mA devices is illusory.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Need to troubleshoot

In the UK 100mA and 300mA types are typically used for equipment protection against fire and where the earth loop impedance is too high to meet required fault disconnection times. They are also used in distribution systems where types with a definite time delay are used to allow them to discriminate with downstream instantaneous RCDs.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Need to troubleshoot

...and you should only be using Type B RCD's (GFCI's) with VFDs. This will pick up the non-linear waveform typical with VFD's.

RE: Need to troubleshoot

4-6ma sensitivity is what is permitted by NEC as personnel GFCI. I would think that any means of early disconnection of a faulty circuit enhances safety, but does not guarantee it if the fault occurs when you touch the faulty equipment.

Also the effect of a shock varies as to which sensitive organ sees the current.

Rafiq Bulsara
http://www.srengineersct.com

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