What does this do and why is it there?

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stephena

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What's the purpose of the ground wire being wrapped around this metalic core thing? It's on a fan for a bathroom.
 

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ptonsparky said:
Take it off and see if any AFCI or GFCI trips in the house while cycling the fan off/on.
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Already left from the house. Does it affect the AFCI or GFCI breakers? Like the first guy said it's weird that it's on the ground wire. How would that effect anything unless it plays some part in ground faults
 
zbang said:
Is there an electronic speed control? It might leak enough RF noise into the EGC to cause trouble (or fail an FCC approval). The ferrite core will suppress that noise; that's the main reason you see them anywhere.
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I was thinking it was to suppress any incoming noise... you're probably right in thinking it's to comply with FCC or international communications regulation(s).
 
stephena said:
Already left from the house. Does it affect the AFCI or GFCI breakers? Like the first guy said it's weird that it's on the ground wire. How would that effect anything unless it plays some part in ground faults
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IDK. in the earlier days of AFCIs we tried about everything to keep them from nuisance tripping and if I had had a couple I would have tried it.
 
stephena said:
What's the purpose of the ground wire being wrapped around this metalic core thing? It's on a fan for a bathroom.
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What's the make and model of the fan? And what were the features, if any, like light, humidity sense, occupancy sense?

This is intriguing. I'd like to know more, as well.
 
dmxtothemax said:
They are to suppress high frequency noise,
weather it is incoming or out going we cannot say
but it works any way
WILL NOT EFFECT GFCI.

its called a ferrite core.
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. Never say never.

One of the homes we worked on years ago had lightning strike a tree in the back yard. We discovered obvious arc marks on all the lamp sockets of the screw shell to the mounting screw. Recessed cans.

Lightning protection for controls of the fan?
 
I'd guess the fan has some sort of electronic speed control, a likely culprit now is what are called ECMs, Electronically Commutated Motors, which are becoming popular on high end appliances that boast high energy efficiency. It's basically a 3 phase PMDC motor with a built-in VFD that is fed by single phase power. The VFD component then will produce a lot of common mode noise, meaning expressed onto the ground reference. So this is a common mode choke to try to keep it from interfering with other things in the area.

https://yorkcentraltechtalk.wordpress.com/2012/09/11/what-is-an-ecm-motor/
 
JFletcher said:
I was thinking it was to suppress any incoming noise... you're probably right in thinking it's to comply with FCC or international communications regulation(s).
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That may be true if the ferrite was part of the listed assembly. It does not appear that way.

I think it's from either a ham or CB operator trying to cut noise to their radio, or part of a snake oil EMF suppressant package sold to the homeowner.

Or, it may be there to take up some slack in the green wire.
 
wallyworld said:
Just an fyi it's called a ferrite bead
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Not quite correct, sir.

https://en.wikipedia.org/wiki/Ferrite_bead

A bead is designed for a single pass through the ferrite material. If more impedance is desired, more beads are used. Beads are commonly used to reduce current on the shield of shielded conductors.

They were invented by Walter Maxwell, W2DU, now deceased. I had the pleasure to know him and considered myself one of his many friends.

When using ferrite chokes, sometimes called cores, if more impedance is needed, more turns are used in the wrap.

Edit to add: Here is a drawing of how ferrite beads are used.

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inductive loads can play havoc when in proximity to connected wires
https://en.wikipedia.org/wiki/Ground_loop_(electricity)



reduces noise, most of the Panasonic bath fans use it. the noise produced by the, probably cheaply made fan unit, can get onto EGC and may play games with A/Gfi recepts or ocpd's

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Thank you all for your help on this. I love this site and forum because it constantly teaches me something new making me a better electrician
 
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