Hi,

I am thinking about installing low voltage landscape lighting (12v). I
learned of voltage drop in that light bulbs further away from the
transformer will be dimmer than ones closer to the transformer.

The solution is to try and set up your lighting runs such that
clusters of fixtures are sufficiently close together so that the
voltage differentials are small.

My question is would it be possible to also vary the wattages of the
light bulbs on the same run to even out the light output. For example
I would place a 20w bulb close to the transformer. And then further
down the run I would put say a 50w bulb. The 50w bulb would have lower
voltage, due to the power transmission losses, but would draw more
current and hence get to the same light output.

Has anyone tried this? Or is it that in practice it is very difficult
to get the light outputs to match well.

Best, Mike.

On Aug 21, 7:52 am, hobbes wrote:
Hi,

I am thinking about installing low voltage landscape lighting (12v). I
learned of voltage drop in that light bulbs further away from the
transformer will be dimmer than ones closer to the transformer.

That would be the case if the lights were wired in series. But if they
are wired in parallel, each light bulb would get the equivelant
voltage the power supply is capable of. The power rating of the power
supply you get depends on how many bulbs you intend on using.

When I did mine, I ran the wire as a big loop with both ends connected to
the transformer (don't get the ends mixed up). That effectively doubles the
current rating of the wire and halves the voltage drops making for more
consistant brightness.

"Mikepier" wrote in message
oups.com...
On Aug 21, 7:52 am, hobbes wrote:
Hi,

I am thinking about installing low voltage landscape lighting (12v). I
learned of voltage drop in that light bulbs further away from the
transformer will be dimmer than ones closer to the transformer.

That would be the case if the lights were wired in series. But if they
are wired in parallel, each light bulb would get the equivelant
voltage the power supply is capable of. The power rating of the power
supply you get depends on how many bulbs you intend on using.

In article .com,
Mikepier wrote:

On Aug 21, 7:52 am, hobbes wrote:
Hi,

I am thinking about installing low voltage landscape lighting (12v). I
learned of voltage drop in that light bulbs further away from the
transformer will be dimmer than ones closer to the transformer.

That would be the case if the lights were wired in series. But if they
are wired in parallel, each light bulb would get the equivelant
voltage the power supply is capable of. The power rating of the power
supply you get depends on how many bulbs you intend on using.

I think the OP is referring to IIR losses in the wiring. In theory the
voltage to each bulb should be the same, but I can imagine losing
something over a lengthy run. Still I think the idea of successfully
compensating with different wattage bulbs is going to be frustratingly
difficult.

jmagerl wrote:
When I did mine, I ran the wire as a big loop with both ends connected to
the transformer (don't get the ends mixed up). That effectively doubles the
current rating of the wire and halves the voltage drops making for more
consistant brightness.

In a slight variation, you could feed one of the wires at the 'near' end
(the other wire not connected at the 'near' end). Feed the other wire at
the 'far' end. All bulbs will be the same brightness.


"Mikepier" wrote in message
oups.com...
On Aug 21, 7:52 am, hobbes wrote:
Hi,

I am thinking about installing low voltage landscape lighting (12v). I
learned of voltage drop in that light bulbs further away from the
transformer will be dimmer than ones closer to the transformer.

That would be the case if the lights were wired in series. But if they
are wired in parallel, each light bulb would get the equivelant
voltage the power supply is capable of. The power rating of the power
supply you get depends on how many bulbs you intend on using.

If the bulbs are run in series, the current through each bulb is the
same. If the same type bulbs are used, each will be the same brightness.

Wired in parallel, the voltage at the far end is lower because of
voltage drop along the wire as the OP said.

--
bud--

If the bulbs are run in series, the current through each bulb is the same.

True

If the same type bulbs are used, each will be the same brightness.

Not true. While the current is the same, the voltage across each bulb
will not be the same because of the voltage drop across each bulb.

Wired in parallel, the voltage at the far end is lower because of
voltage drop along the wire as the OP said.

I think you have your series and parallel circuits mixed up. You will
definately have a lower voltage at the far end if you wired the bulbs
in series, but if you wire them in parallel, and assuming you use a
heavy guage wire and a high KVA power supply, you should get little or
no voltage drop at the far end.

"Mikepier" wrote in message
ps.com...
If the bulbs are run in series, the current through each bulb is the
same.

True

If the same type bulbs are used, each will be the same brightness.

Not true. While the current is the same, the voltage across each bulb
will not be the same because of the voltage drop across each bulb.

Wired in parallel, the voltage at the far end is lower because of
voltage drop along the wire as the OP said.

I think you have your series and parallel circuits mixed up. You will
definately have a lower voltage at the far end if you wired the bulbs
in series, but if you wire them in parallel, and assuming you use a
heavy guage wire and a high KVA power supply, you should get little or
no voltage drop at the far end.


Think out what you're saying. In series the bulbs will be the same
brightness. This statement is dead wrong: "You will definately have a lower
voltage at the far end if you wired the bulbs in series"

Al

In article ,
"Big Al" wrote:

"Mikepier" wrote in message
ps.com...
If the bulbs are run in series, the current through each bulb is the
same.

True

If the same type bulbs are used, each will be the same brightness.

Not true. While the current is the same, the voltage across each bulb
will not be the same because of the voltage drop across each bulb.

Wired in parallel, the voltage at the far end is lower because of
voltage drop along the wire as the OP said.

I think you have your series and parallel circuits mixed up. You will
definately have a lower voltage at the far end if you wired the bulbs
in series, but if you wire them in parallel, and assuming you use a
heavy guage wire and a high KVA power supply, you should get little or
no voltage drop at the far end.


Think out what you're saying. In series the bulbs will be the same
brightness. This statement is dead wrong: "You will definately have a lower
voltage at the far end if you wired the bulbs in series"

Al

Depends entirely on where you put the voltmeter probes. I know what Mike
is getting at, here, but I think he misunderstood your post.

Mikepier wrote:
If the bulbs are run in series, the current through each bulb is the same.

True

If the same type bulbs are used, each will be the same brightness.

Not true. While the current is the same, the voltage across each bulb
will not be the same because of the voltage drop across each bulb.

"Same type bulbs" means same resistance for each bulb. Same current
through same resistance means same voltage drop across each bulb. Same
current and same voltage at each bulb means same wattage at each bulb
and same brightness.


Wired in parallel, the voltage at the far end is lower because of
voltage drop along the wire as the OP said.

I think you have your series and parallel circuits mixed up. You will
definately have a lower voltage at the far end if you wired the bulbs
in series, but if you wire them in parallel, and assuming you use a
heavy guage wire and a high KVA power supply, you should get little or
no voltage drop at the far end.

If the near end bulb gets the same voltage, increasing the power supply
KVA has no effect on voltage drop between ends.

If you use a superconductor there will be no voltage drop at the far
end. The OP asked a question about the wire he was likely to use.

--
bud--

On Tue, 21 Aug 2007 06:58:22 -0700, Mikepier
wrote:

On Aug 21, 7:52 am, hobbes wrote:
Hi,

I am thinking about installing low voltage landscape lighting (12v). I
learned of voltage drop in that light bulbs further away from the
transformer will be dimmer than ones closer to the transformer.

tHERE IS no way the resistance 100 feetaway will make the brightness
of a 50 watt bulb anywhere near as dim as a 20 watt bulb. If there
are such voltage drops and you could get 20, 22, 24, 26 watts, that
might work. I don't know if there are voltage drops at all. If the
proper gauge wire is used, there won't be, but and I have no
experience with this, if they include really thin wire, maybe that
could happen. A much better plan is to find out what kind of wire you
need, and use that

You should have said if you are wiring in parallel or series, but at
12volts I assume it is parallel. Yes?

That would be the case if the lights were wired in series. But if they
are wired in parallel, each light bulb would get the equivelant
voltage the power supply is capable of.

Not if the wires are too thin, which is the only way I can imagine the
bulbs dimming. Then, there is cumulative voltage drop from the wire
resistance, increasing at each bulb, the farther away one gets from
the 12v transformer.

OTOH, if the wiring were in series there would be proportional voltage
drop across far light bulbs compared to near ones. The current would
be the same for all and the voltage drop would be directly
proportional to the resistance of each bulb. Unrelated to the bulbs
distance from the power source.

The power rating of the power
supply you get depends on how many bulbs you intend on using.

In article ,
mm wrote:

You should have said if you are wiring in parallel or series, but at
12volts I assume it is parallel. Yes?



Yes. No such thing as series low voltage lighting. That would sort of be
a contradiction in terms, as to light ten 12V bulbs, you'd need to start
out with 120 volts.