I bought a distribution block and I have two amps. Do I need to go
from amps--fuse--distribution block--fuse--battery? Can I skip
the fuse before the distribution block or is it important?

On Sun, 28 Dec 2003 08:10:18 GMT, Alan wrote:

I bought a distribution block and I have two amps. Do I need to go
from amps--fuse--distribution block--fuse--battery? Can I skip
the fuse before the distribution block or is it important?

Not sure from your description what you mean by "before" the
distribution block, but here's my suggestion, starting with the
battery.

Start at the battery, then run wire to a fuse no further than 18
inches from the battery. From the fuse, go back to your distribution
block. You don't need to put fuses between the distribution block and
the amps unless the amps don't have fuses of their own.

The purpose for the fuse near the battery is to protect your car, not
your amps. If any part of the wire running from the battery back to
your distribution block or from your distribution block to the amps
were to rub through and contact ground, the fuse near the battery will
blow, rather than the entire length of wire between the battery and
the short catching fire. Use a fuse near the battery with a rating
equal to both of your amps' fuses combined. For instance, if one amp
has two 40-amp fuses, and the other amp has two 30-amp uses, use at
least a 140-amp fuse near the battery. Alternatively, you could use a
circuit breaker instead of a fuse.

I used the 18-inch guideline because I think that's the rule that
IASCA has for competition cars. In practice, the closer to the
battery that you can put the fuse, the better. Because the fuse won't
protect against a short to ground between the battery and the fuse,
you want to minimize that distance.


Scott Gardner

Wow, you're the first person I've seen (besides me) that doesn't like the
extra fus in the back when the amps already have one. Cool.


Paul Vina



"Scott Gardner" wrote in message
...
On Sun, 28 Dec 2003 08:10:18 GMT, Alan wrote:

I bought a distribution block and I have two amps. Do I need to go
from amps--fuse--distribution block--fuse--battery? Can I skip
the fuse before the distribution block or is it important?

Not sure from your description what you mean by "before" the
distribution block, but here's my suggestion, starting with the
battery.

Start at the battery, then run wire to a fuse no further than 18
inches from the battery. From the fuse, go back to your distribution
block. You don't need to put fuses between the distribution block and
the amps unless the amps don't have fuses of their own.

The purpose for the fuse near the battery is to protect your car, not
your amps. If any part of the wire running from the battery back to
your distribution block or from your distribution block to the amps
were to rub through and contact ground, the fuse near the battery will
blow, rather than the entire length of wire between the battery and
the short catching fire. Use a fuse near the battery with a rating
equal to both of your amps' fuses combined. For instance, if one amp
has two 40-amp fuses, and the other amp has two 30-amp uses, use at
least a 140-amp fuse near the battery. Alternatively, you could use a
circuit breaker instead of a fuse.

I used the 18-inch guideline because I think that's the rule that
IASCA has for competition cars. In practice, the closer to the
battery that you can put the fuse, the better. Because the fuse won't
protect against a short to ground between the battery and the fuse,
you want to minimize that distance.


Scott Gardner

I'm not adamant about it one way or the other, but I try not to use
unnecessary fuses. One time where I will use a fuse between a
distribution block and a component is if I have a small-gauge wire
connecting the two. For instance, my Epicenter is powered from a
distribution block using an 18- or 20-gauge wire, since it only draws
a few amps. I put a fuse in that wire because if the small wire were
to short to ground, there's a chance that the insulation could melt or
catch fire before the fuse near the battery blew.



Scott Gardner

On Sun, 28 Dec 2003 17:56:05 GMT, "Paul Vina"
wrote:

Wow, you're the first person I've seen (besides me) that doesn't like the
extra fus in the back when the amps already have one. Cool.


Paul Vina



"Scott Gardner" wrote in message
...
On Sun, 28 Dec 2003 08:10:18 GMT, Alan wrote:

I bought a distribution block and I have two amps. Do I need to go
from amps--fuse--distribution block--fuse--battery? Can I skip
the fuse before the distribution block or is it important?

Not sure from your description what you mean by "before" the
distribution block, but here's my suggestion, starting with the
battery.

Start at the battery, then run wire to a fuse no further than 18
inches from the battery. From the fuse, go back to your distribution
block. You don't need to put fuses between the distribution block and
the amps unless the amps don't have fuses of their own.

The purpose for the fuse near the battery is to protect your car, not
your amps. If any part of the wire running from the battery back to
your distribution block or from your distribution block to the amps
were to rub through and contact ground, the fuse near the battery will
blow, rather than the entire length of wire between the battery and
the short catching fire. Use a fuse near the battery with a rating
equal to both of your amps' fuses combined. For instance, if one amp
has two 40-amp fuses, and the other amp has two 30-amp uses, use at
least a 140-amp fuse near the battery. Alternatively, you could use a
circuit breaker instead of a fuse.

I used the 18-inch guideline because I think that's the rule that
IASCA has for competition cars. In practice, the closer to the
battery that you can put the fuse, the better. Because the fuse won't
protect against a short to ground between the battery and the fuse,
you want to minimize that distance.


Scott Gardner

Wow, you're the first person I've seen (besides me) that doesn't like the
extra fus in the back when the amps already have one. Cool.

That's not what a rear fuse is for anyway. That secondary wire fuse is for
the wire, not the amp. Having said that, I rarely use one either. The only
time I do is if the wire from the distro block to the amplifier has to be
run under carpet along a metal chassis or something. That tends not to be
the case.

I know. The fuse by the battery protects the car and the main power lead
and th one in the back (either in the amp or in the block) is to protect the
amp. IASCAs been telling everyone for years that they need fusing in the
back (even when the amps already have them) no matter what and that just
isn't the case.



Paul Vina



"Mark Zarella" wrote in message
...
Wow, you're the first person I've seen (besides me) that doesn't like
the
extra fus in the back when the amps already have one. Cool.

That's not what a rear fuse is for anyway. That secondary wire fuse is
for
the wire, not the amp. Having said that, I rarely use one either. The
only
time I do is if the wire from the distro block to the amplifier has to be
run under carpet along a metal chassis or something. That tends not to be
the case.

I know. The fuse by the battery protects the car and the main power lead
and th one in the back (either in the amp or in the block) is to protect
the
amp.

No. That's not what I said. I realize I was unclear the first time. What
I meant was that the fuse in the back is to protect the wire coming out of
the distro block. Hence the (common) use of fused distro blocks. It may or
may not protect the amp in the process. My point was that it "should" be
used even if the amp has a fuse. Anytime there's a step down in wire size.
Some guys (John Durbin?) usually insist on it. But in all honesty, I don't
use one all that often. Only in cases where I feel there's a good chance of
shorting the smaller wire.

I meant was that the fuse in the back is to protect the wire coming out of
the distro block. Hence the (common) use of fused distro blocks. It may or
may not protect the amp in the process. My point was that it "should" be
used even if the amp has a fuse. Anytime there's a step down in wire size.
Some guys (John Durbin?) usually insist on it. But in all honesty, I don't
use one all that often. Only in cases where I feel there's a good chance of
shorting the smaller wire.


NEC code requires a fuse/circuit breaker anytime there is a change in wire
size.
And while there is good in the car if you actually short the wire to groud then
the main fuse will trip. I think if you make sure you are not going to exceed
the capabilities of the smaller wire with the load presented then I dont worry
about it. But thats just me.

Les

"Paul Vina" wrote in message
news:VOEHb.680127$Tr4.1699011@attbi_s03...
Wow, you're the first person I've seen (besides me) that doesn't like the
extra fus in the back when the amps already have one. Cool.


Paul Vina

it's like anything it's always better to have it, and never need it then be
LOS

"Paul Vina" wrote in message
news:2M%Hb.957$I07.1410@attbi_s53...
I know. The fuse by the battery protects the car and the main power lead
and th one in the back (either in the amp or in the block) is to protect
the
amp. IASCAs been telling everyone for years that they need fusing in the
back (even when the amps already have them) no matter what and that just
isn't the case.



Paul Vina

it's to keep the car from setting of fire, that's why we have fuses

On Wed, 31 Dec 2003 06:23:28 -0500, "Tha Ghee"
wrote:

"Paul Vina" wrote in message
news:VOEHb.680127$Tr4.1699011@attbi_s03...
Wow, you're the first person I've seen (besides me) that doesn't like the
extra fus in the back when the amps already have one. Cool.


Paul Vina

it's like anything it's always better to have it, and never need it then be
LOS


Except that from an engineering/cost standpoint, adding a fuse between
the distribution block and the amp adds two more connections, a fuse
holder, and a fuse. The whole point that Paul and I were making is
that there are times when not only are extra fuses between the distro
blocks and components not necessary, but they wouldn't be of any use
even if you put them in there.

Scott Gardner

We covered that already.



Paul Vina



"Tha Ghee" wrote in message
...
"Paul Vina" wrote in message
news:2M%Hb.957$I07.1410@attbi_s53...
I know. The fuse by the battery protects the car and the main power
lead
and th one in the back (either in the amp or in the block) is to protect
the
amp. IASCAs been telling everyone for years that they need fusing in
the
back (even when the amps already have them) no matter what and that just
isn't the case.



Paul Vina

it's to keep the car from setting of fire, that's why we have fuses

It's not necessarily better. I haven't seen a fuse yet without some voltage
drop. That's more voltage that my amps could have. It may be a small,
probably insignifcant amount, but that's not the point.



Paul Vina



"Tha Ghee" wrote in message
...
"Paul Vina" wrote in message
news:VOEHb.680127$Tr4.1699011@attbi_s03...
Wow, you're the first person I've seen (besides me) that doesn't like
the
extra fus in the back when the amps already have one. Cool.


Paul Vina

it's like anything it's always better to have it, and never need it then
be
LOS

It's not necessarily better. I haven't seen a fuse yet without some
voltage
drop. That's more voltage that my amps could have. It may be a small,
probably insignifcant amount, but that's not the point.

No, that sort of IS the point. If it's small and insignificant, then you
can't use v drop as a defense.

On Wed, 31 Dec 2003 16:23:01 -0500, "Mark Zarella"
wrote:

It's not necessarily better. I haven't seen a fuse yet without some
voltage
drop. That's more voltage that my amps could have. It may be a small,
probably insignifcant amount, but that's not the point.

No, that sort of IS the point. If it's small and insignificant, then you
can't use v drop as a defense.

Then I guess we're just back to the unnecessary added complexity and
cost.

Scott Gardner

"Scott Gardner" wrote in message
...
On Wed, 31 Dec 2003 06:23:28 -0500, "Tha Ghee"
wrote:

"Paul Vina" wrote in message
news:VOEHb.680127$Tr4.1699011@attbi_s03...
Wow, you're the first person I've seen (besides me) that doesn't like
the
extra fus in the back when the amps already have one. Cool.


Paul Vina

it's like anything it's always better to have it, and never need it then
be
LOS


Except that from an engineering/cost standpoint, adding a fuse between
the distribution block and the amp adds two more connections, a fuse
holder, and a fuse. The whole point that Paul and I were making is
that there are times when not only are extra fuses between the distro
blocks and components not necessary, but they wouldn't be of any use
even if you put them in there.

Scott Gardner

got ya, don't want to increase resistance ok. sorry.

"Scott Gardner" wrote in message
...
On Wed, 31 Dec 2003 16:23:01 -0500, "Mark Zarella"
wrote:

It's not necessarily better. I haven't seen a fuse yet without some
voltage
drop. That's more voltage that my amps could have. It may be a small,
probably insignifcant amount, but that's not the point.

No, that sort of IS the point. If it's small and insignificant, then you
can't use v drop as a defense.

Then I guess we're just back to the unnecessary added complexity and
cost.

Scott Gardner

just remember to KiSS and you'll have less problems.

On Wed, 31 Dec 2003 20:59:28 -0500, "Tha Ghee"
wrote:

"Scott Gardner" wrote in message
...
On Wed, 31 Dec 2003 16:23:01 -0500, "Mark Zarella"
wrote:

It's not necessarily better. I haven't seen a fuse yet without some
voltage
drop. That's more voltage that my amps could have. It may be a small,
probably insignifcant amount, but that's not the point.

No, that sort of IS the point. If it's small and insignificant, then you
can't use v drop as a defense.

Then I guess we're just back to the unnecessary added complexity and
cost.

Scott Gardner

just remember to KiSS and you'll have less problems.


Right, which is why I don't use fuses that serve no purpose.

Scott

just remember to KiSS and you'll have less problems.


Right, which is why I don't use fuses that serve no purpose.

But they DO serve a purpose.

On Wed, 31 Dec 2003 21:10:38 -0500, "Mark Zarella"
wrote:

just remember to KiSS and you'll have less problems.


Right, which is why I don't use fuses that serve no purpose.

But they DO serve a purpose.


Not all fuses do serve a purpose - consider this example:

From battery, run 4ga wire 12" to a fuse. Continue the 4ga back to
the distribution block. From the block, you have two 4ga wires going
to amps that have their own internal fuses. Putting additional fuses
between the distribution block and the amps would be redundant. Any
short to ground anywhere along the wire (after the first 12 inches, of
course) would blow the fuse near the battery.

Scott Gardner

Not all fuses do serve a purpose - consider this example:

From battery, run 4ga wire 12" to a fuse. Continue the 4ga back to
the distribution block. From the block, you have two 4ga wires going
to amps that have their own internal fuses. Putting additional fuses
between the distribution block and the amps would be redundant. Any
short to ground anywhere along the wire (after the first 12 inches, of
course) would blow the fuse near the battery.

In that case, there's no point. But in the case of running a 2ga. to a
distro, where 8ga. go to the amps, then it can serve a purpose.

On Wed, 31 Dec 2003 21:24:05 -0500, "Mark Zarella"
wrote:

Not all fuses do serve a purpose - consider this example:

From battery, run 4ga wire 12" to a fuse. Continue the 4ga back to
the distribution block. From the block, you have two 4ga wires going
to amps that have their own internal fuses. Putting additional fuses
between the distribution block and the amps would be redundant. Any
short to ground anywhere along the wire (after the first 12 inches, of
course) would blow the fuse near the battery.

In that case, there's no point. But in the case of running a 2ga. to a
distro, where 8ga. go to the amps, then it can serve a purpose.


In a less-extreme example, I wonder whether they'd be necessary if you
had 2ga going to the distribution block and 4-gauge going to the amps?

It would depend on what the rating of the fuse near the battery was,
but I still think the fuse near the battery would pop before the
4-gauge wire even got hot.

Anyway, my point was to use them where they're needed rather than
using them for the sake of using them.

Scott Gardner

In a less-extreme example, I wonder whether they'd be necessary if you
had 2ga going to the distribution block and 4-gauge going to the amps?

It would depend on what the rating of the fuse near the battery was,
but I still think the fuse near the battery would pop before the
4-gauge wire even got hot.

Anyway, my point was to use them where they're needed rather than
using them for the sake of using them.

I don't know. Some people in here (John Durbin?) have reported resistive
shorts starting a fire but not popping the oversized fuse. Never happened
to me, and it's not very often that I use them. I'm only saying that there
is a point to them.

In a less-extreme example, I wonder whether they'd be necessary if you
had 2ga going to the distribution block and 4-gauge going to the amps?

It would depend on what the rating of the fuse near the battery was,
but I still think the fuse near the battery would pop before the
4-gauge wire even got hot.

Anyway, my point was to use them where they're needed rather than
using them for the sake of using them.


I would think if you have 4ga back and 4ga after the distribution block, extra
fuses would be redundant. But, I believe that anytime there is a drop in wire
size, it should be fused.

I would think if you have 4ga back and 4ga after the distribution block,
extra
fuses would be redundant. But, I believe that anytime there is a drop in
wire
size, it should be fused.



Why?



Paul Vina

On Thu, 01 Jan 2004 07:13:12 GMT, "Paul Vina"
wrote:

I would think if you have 4ga back and 4ga after the distribution block,
extra
fuses would be redundant. But, I believe that anytime there is a drop in
wire
size, it should be fused.



Why?



Paul Vina

The reasoning is that if you have a smaller wire coming off of
the distribution block without a fuse, and that wire shorts to ground,
the smaller wire could melt its insulation or even catch fire, without
the fuse near the battery blowing.
For instance, if you have a 150-amp fuse near the battery,
4-gauge running back to the distro block, and then a run of 18-gauge
from the distro block to an EQ, signal processor, or other low-drain
component, it would be wise to fuse the 18-gauge wire close to the
distro block. If you didn't and the 18-gauge wire shorted to ground,
it could very well go up in smoke long before the 150 amp fuse near
the battery blew.

Scott Gardner

The reasoning is that if you have a smaller wire coming off of
the distribution block without a fuse, and that wire shorts to ground,
the smaller wire could melt its insulation or even catch fire, without
the fuse near the battery blowing.
For instance, if you have a 150-amp fuse near the battery,
4-gauge running back to the distro block, and then a run of 18-gauge
from the distro block to an EQ, signal processor, or other low-drain
component, it would be wise to fuse the 18-gauge wire close to the
distro block. If you didn't and the 18-gauge wire shorted to ground,
it could very well go up in smoke long before the 150 amp fuse near
the battery blew.


What he said. Besides, I'd rather be safe then sorry, and fused distribution
blocks are only ~$4 more. I recently ordered from knukonceptz.com, a fused
block for power and an unfused for ground. Nice stuff, fused one was $10 and
unfused one was $6.

The reasoning is that if you have a smaller wire coming off of
the distribution block without a fuse, and that wire shorts to ground,
the smaller wire could melt its insulation or even catch fire, without
the fuse near the battery blowing.
For instance, if you have a 150-amp fuse near the battery,
4-gauge running back to the distro block, and then a run of 18-gauge
from the distro block to an EQ, signal processor, or other low-drain
component, it would be wise to fuse the 18-gauge wire close to the
distro block. If you didn't and the 18-gauge wire shorted to ground,
it could very well go up in smoke long before the 150 amp fuse near
the battery blew.

Scott Gardner


Ok. That makes sense. But if that were to happen I think one of two things
would happen; 1) 18 ga wire would burn up severing contact with the battery
(almost like a fusible link) or 2) the battery would and pop the fuse.

I'm not saying these are correct, but logically (it's the lefty in me) they
make sense.


Paul Vina

Ok. That makes sense. But if that were to happen I think one of two
things
would happen; 1) 18 ga wire would burn up severing contact with the
battery
(almost like a fusible link)

That's what could cause the fire.

or 2) the battery would and pop the fuse.

It's hard to say whether or not you'd pop the fuse. With the 18ga wire, I
wouldn't count on it. I'd most certainly fuse the 18ga. wire. But when
it's a matter of going from, say, 4ga down to 8ga it doesn't matter much.

You probably should fuse at the back especially when changing wir
sizes. Read this:

http://tinyurl.com/yrfd
-
jsche
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Good page, and no one's arguing that fuses after the distribuition
block aren't a good idea - when you have a drop in wire size. If you
have the same size wire before and after the distribution block, and
the components powered by the distribution block have their own
internal fuses, extra fuses between the block and the components are
redundant.

Scott Gardner


On Fri, 02 Jan 2004 05:38:13 GMT, jschen
wrote:

You probably should fuse at the back especially when changing wire
sizes. Read this:

http://tinyurl.com/yrfdo
--
jschen
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