GFCI on XMAS Lites

[mark.lobach]

We have a requirement to use GFCI's on xmas lights where I work. Can't
keep many from tripping.Anyone have any experience with this? Do we need
GFCI? How can we keep the lights on?

 

[Clive Mitchell]

We have a requirement to use GFCI's on xmas lights where I work. Can't
keep many from tripping.Anyone have any experience with this? Do we
need GFCI? How can we keep the lights on?

Are they tripping due to actual earth leakage in wet surroundings?

If they are actually doing their intended job then there's not much you
can do other than segregate the circuits into smaller protected zones to
minimise the amount of lights that go out in affected areas. It might
also be a good idea to assess how your lights are constructed to see if
there is an intrinsic problem in the design.

As mentioned earlier, I do the lights in Glasgow's George Square, and
many of the lighting effects are over 10 years old and very problematic.
The whole square is permanently protected by a primary earth leakage
circuit breaker that has a high 1A setting and a short time delay to let
sub-protection attempt to clear the fault. In many cases where a fault
goes to earth, the local over-current protection kills the circuit
before the earth leakage protection is required. However most of the
faults are Live to Neutral (waterlogged festoon lampholders), so in
those instances the earth leakage isn't affected anyway.

The lower effects that are in reach of drunks and wilful members of the
public who climb over fences to reach them, are protected by secondary
earth leakage protection at normal levels for the UK (30mA instant).

Is this any help? Or could your problem be associated with using the
protection on the flashing side of circuits where the power is
continually cycling on and off. This could cause nuisance tripping of
ordinary RCD's or GFCI's.

Can you describe your situation in a bit more detail?

 

[mark.lobach]

Yes we are using standard strings of lights 75 to 100 per string. The
voltage is 120V. we are using 5ma GFCI's. The lights are atually laying
on the ground. If we bypass the GFCI they hold just fine. When we put
the 5ma trip GFCI in, some trip right away some stay on for 10 to 20
minutes. I think the 30ma trip GFCI would work but we need to use the
5ma GFCI..

Thanks

 

[Clive Mitchell]

Yes we are using standard strings of lights 75 to 100 per string. The
voltage is 120V. we are using 5ma GFCI's. The lights are atually laying
on the ground. If we bypass the GFCI they hold just fine. When we put
the 5ma trip GFCI in, some trip right away some stay on for 10 to 20
minutes. I think the 30ma trip GFCI would work but we need to use the
5ma GFCI..

Can we assume that it's leakage to ground caused by moisture? In this
application we would tend to use low voltage lights in the UK. Either
in the form of parallel pea-light or the groovy new LED strings that
I've been using for the first time this year.

Is laying the lights directly on the ground a good idea? It sounds like
a bit of a GFI nightmare if it rains. Capillary action will always draw
the water into the tiniest space, and this probably means up the rear
end of the lampholder and onto the internal contacts. Maybe at worst
you could support the lights above the ground on non conductive catenary
cords.

 

[mark.lobach]

Yes, leakage to ground is the problem.
We are using LED lights this year for the first time also. They look
great and draw very little current. But they are still 110 volt strings.
I agree that the light on the ground is asking for trouble - even on a
dry day, but just thought I would ask to see if I was missing something.
Do you have a source for low voltage lights? 24VAC??

Thanks
mark

 

[Andrew Gabriel]

Yes, leakage to ground is the problem.
We are using LED lights this year for the first time also. They look
great and draw very little current. But they are still 110 volt strings.
I agree that the light on the ground is asking for trouble - even on a
dry day, but just thought I would ask to see if I was missing something.
Do you have a source for low voltage lights? 24VAC??

In the UK, our shops are stuffed full of them.

 

[Clive Mitchell]

Yes, leakage to ground is the problem.
We are using LED lights this year for the first time also. They look
great and draw very little current. But they are still 110 volt
strings. I agree that the light on the ground is asking for trouble -
even on a dry day, but just thought I would ask to see if I was missing
something.
Do you have a source for low voltage lights? 24VAC??

I'm in the UK where the standard voltage for outdoor Christmas lighting
seems to be either 12V or 24V with the occasional 36V system. We do
have 240V outdoor sets, but they tend to have excessively thick and
clumsy cable and bulky lampholders with sealing grommets.