This morning about 9am, i noticed the classic wasnt charging. Looking at it, the ground fault led was on. It wasnt beeping though, which i thought it would/should.
This i thought to be rather odd, as our wiring is pretty tight. Rebooted classic, and it went into bulk as normal. No sign of it since.
I realise that pv ground fault interupters arent well regarded, so maybe its time to turn it off.
Quote from: zoneblue on December 14, 2013, 09:40:03 PM
I realise that pv ground fault interupters arent well regarded, so maybe its time to turn it off.
Remember that the GFP serves as your bond between DC neg and ground. If you turn it off, be sure to make a bond somewhere.
--vtMaps
Hi ZB,
I remember Ryan's (not Midnite) advice in a post to keep a negative bond with GFP enable (or not) for off grid system for safety in case of ground fault.
Quote from: SolarMusher on December 15, 2013, 11:24:00 AM
I remember Ryan's (not Midnite) advice in a post to keep a negative bond with GFP enable (or not) for off grid system for safety in case of ground fault.
If you have a bond elsewhere in the system the GFP can NOT be enabled. Whether or not that increases safety is controversial and depends upon the location and type of ground fault. In some instances a GFP can provide a measure of safety, but in other instances it can worsen the situation.
On balance, many of the smartest folks around here feel they are better off without GFP.
If you want the safest system possible, you want an arc fault combiner box.
--vtMaps
Quote from: vtmaps on December 15, 2013, 11:36:12 AM
Quote from: SolarMusher on December 15, 2013, 11:24:00 AM
I remember Ryan's (not Midnite) advice in a post to keep a negative bond with GFP enable (or not) for off grid system for safety in case of ground fault.
If you have a bond elsewhere in the system the GFP can NOT be enabled.
--vtMaps
Hi vt,
That was not what Ryan said:
«Sure I enable the GFP but it will never detect a fault as the jumper in the E-Panel over rides the GFP device. Ryan»vt could you explain your point of view.
Thanks,
Erik
Quote from: SolarMusher on December 15, 2013, 11:48:59 AM
vt could you explain your point of view.
My point of view is that there must always be a bond between DC negative and ground.
A GFP works by using a small (1 amp or less) circuit breaker as the bond between DC negative and ground.
If there is a parallel ground fault between DC positive and ground, the fault current will trip the breaker. The little GFP breaker is ganged to a larger breaker that disconnects the PV positive or battery positive..
If you have a bond anywhere else in the system, that bond will short out the little GFP breaker and the GFP cannot be functional.
A major problem with GFP is that when it trips the system is unbonded and therefore floating. Floating systems are OK in some situations, but there must be fuses or circuit breakers on all Positive AND Negative conductors.
Danger: when the system is unbonded, any negative wire (like in a DC lamp) could be at Voc above ground.
--vtMaps
Which was why i was suprised it didnt beep. To let you know about it.
Anyway the ground fault was enabled on the classic before i found out about the politics of the matter, and next time im working in there will add some 6mm2 from neg to ground.
Zone Blue
Is this a Classic Lite? If so there is no speaker to make it beep like there is on the Standard Classic. You only get a visual indicator on the Lite
Ryan
yes, lite.
Ryan, have you seen any false trips with these before? It happened again today, in float. Was maybe 36 hours since last time. Or do i actually HAVE a ground fault? Whats the best way to test for a ground fault? Disable the ground fault interupter, and test for ground - positive potential?
ZB there was another case of a trip, and the end result is/was.... you guessed it there WAS a GF .. boB's Classics don't lie... don't remember where it was but seems it was a single strand of wire.
Yes the Classic will not throw false GFs so there must be an issue? What I do to verify it is use say a 1 amp fues in between ground and negative and then remove the jumper from the Classic. if the fuse blows there is a problem.
It takes about 0.5 to 0.75 amps to trigger the Classics GF
Ryan