[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Ballast grounding & GFIs

In Aquatic Plants Digest Volume 04 : Number 026,  
Jamie Noble brought up some points about flu.lamp ballasts and 
GFI outlets that I feel should be clarified...

1. Magnetic ballasts require the bulbs be mounted within a certain 
distance of a grounded surface to help start the lamps under 
certain conditions (mainly cold temps.).  This will not prevent 
electric shock.

2. I feel than the basic operation of GFIs is generally not 
understood...leading to potentially serious consequences.
In North American homes the power provided is ground referenced.  
What this means is that one of the conductors (the 'neutral') is 
actually connected to ground.  This is allowed to occur in only one 
place per home - at the breaker panel.  Since the electricity flows 
between the 'line' and 'neutral' conductors, one can be electrocuted 
by touching the 'line' and something grounded (since the electricity 
would return to the 'neutral' conductor through the ground path).  
The is where GFI protected systems provide benefit.  Ground Fault 
Interrupters operate by monitoring the current flowing in both the 
'line' and 'neutral' conductors.  Under 'safe' conditions, the currents 
in the 'line' and 'neutral' should be equal.  An unsafe condition 
exists with there is an imbalance between the two currents.  This 
can occur when contact is made with the 'line' conductor and a 
grounded object.  The current is now partially/completely flowing 
between the 'line' conductor being contacted, through ground, and 
back to the grounded 'neutral' conductor at the breaker panel.  The 
GFI is designed to turn off the power when this, and ONLY this, 
condition occurs.
The GFI will NOT protect you under the following conditions(just a 
	-Contacting both the 'line' and 'neutral' conductors.
	-Contacting the output of a ballast or transformer (since they 


Torsten's 2cents from snow covered
Lynden, Ontario