Peavey XR 886, 1997, mixer amp
 

"Eeyore" wrote in message
...


gareth magennis wrote:

So what would be the maximum voltage drop you might expect from a non
overloaded mains system?

Crikey. I know where I'd test with a highish power PA rig, the local venue
that
has some 5kW ? or so of amps but last year I had a separate 32A circuit
run in
just for the amp rack so I doubt it would be more than a few volts.

Graham



I was just curious, knowing nothing really about wiring regulations.

If the regulations require heavier cable for longer runs to prevent voltage
drop, then is there some kind of formula with voltage drop limits? Or can
you just run a very long cable (in a large building) capable of carrying the
current required and have to live with the voltage drop. Or is any voltage
drop just a few volts as you suspect, so the point is mute.

Kind of thing.



Gareth.

Peavey XR 886, 1997, mixer amp
 

gareth magennis wrote:

"Eeyore" wrote
gareth magennis wrote:

So what would be the maximum voltage drop you might expect from a non
overloaded mains system?

Crikey. I know where I'd test with a highish power PA rig, the local venue
that has some 5kW ? or so of amps but last year I had a separate 32A circuit

run in just for the amp rack so I doubt it would be more than a few volts.


I was just curious, knowing nothing really about wiring regulations.

If the regulations require heavier cable for longer runs to prevent voltage
drop, then is there some kind of formula with voltage drop limits? Or can
you just run a very long cable (in a large building) capable of carrying the
current required and have to live with the voltage drop. Or is any voltage
drop just a few volts as you suspect, so the point is mute.

Well, a 'spur' rated at 32A requires 6mm2 cable. You could calculate a voltage
drop along that based on resistance data. There is AFAIK no limit on length
aside from practical limitations ! I don't know how the incoming feed from the
electric company to the breaker box might drop with load though.

Graham

Peavey XR 886, 1997, mixer amp
 

Eeyore wrote:


gareth magennis wrote:


"Eeyore" wrote

gareth magennis wrote:


So what would be the maximum voltage drop you might expect from a non
overloaded mains system?

Crikey. I know where I'd test with a highish power PA rig, the local venue
that has some 5kW ? or so of amps but last year I had a separate 32A circuit

run in just for the amp rack so I doubt it would be more than a few volts.


I was just curious, knowing nothing really about wiring regulations.

If the regulations require heavier cable for longer runs to prevent voltage
drop, then is there some kind of formula with voltage drop limits? Or can
you just run a very long cable (in a large building) capable of carrying the
current required and have to live with the voltage drop. Or is any voltage
drop just a few volts as you suspect, so the point is mute.


Well, a 'spur' rated at 32A requires 6mm2 cable. You could calculate a voltage
drop along that based on resistance data. There is AFAIK no limit on length
aside from practical limitations ! I don't know how the incoming feed from the
electric company to the breaker box might drop with load though.

Graham

In the US, it's no less than 5% drop from the source to the load at full
load.. conductor must be rated to supply a min of 95%.

for example, 10 awg = 0.999/M or 3.28/kg ohms

of course, all conductors are based from copper, copper being 100% of
the scale. All others are based from that.
etc..


http://webpages.charter.net/jamie_5"

Peavey XR 886, 1997, mixer amp
 

gareth magennis wrote:


I was just curious, knowing nothing really about wiring regulations.

If the regulations require heavier cable for longer runs to prevent voltage
drop, then is there some kind of formula with voltage drop limits? Or can
you just run a very long cable (in a large building) capable of carrying the
current required and have to live with the voltage drop. Or is any voltage
drop just a few volts as you suspect, so the point is mute.

Kind of thing.



Gareth.



I haven't looked it up properly but in the design of fixed installations
you are not supposed to have more than a 4% voltage drop from the point
of supply. So whilst 6mm cable will easily carry 32A, once you go over
a certain length you would need to go up to 10mm to comply with the regs.

http://www.tlc-direct.co.uk/Technica...ltageDrop.html

--
Tim Phipps

replace "invalid" with "uk" to reply by email

Peavey XR 886, 1997, mixer amp
 

"Tim Phipps" wrote in message
...
gareth magennis wrote:


I was just curious, knowing nothing really about wiring regulations.

If the regulations require heavier cable for longer runs to prevent
voltage drop, then is there some kind of formula with voltage drop
limits? Or can you just run a very long cable (in a large building)
capable of carrying the current required and have to live with the
voltage drop. Or is any voltage drop just a few volts as you suspect, so
the point is mute.

Kind of thing.



Gareth.

I haven't looked it up properly but in the design of fixed installations
you are not supposed to have more than a 4% voltage drop from the point of
supply. So whilst 6mm cable will easily carry 32A, once you go over a
certain length you would need to go up to 10mm to comply with the regs.

http://www.tlc-direct.co.uk/Technica...ltageDrop.html

--
Tim Phipps



Thanks. Then from my calculations the maximum legal drop for any
installation should be 13.6% from 240v - 207v and a bit, not including
your own power distro.


Gareth.

Peavey XR 886, 1997, mixer amp
 

"gareth magennis" wrote in message
...

"Tim Phipps" wrote in message
...
gareth magennis wrote:


I was just curious, knowing nothing really about wiring regulations.

If the regulations require heavier cable for longer runs to prevent
voltage drop, then is there some kind of formula with voltage drop
limits? Or can you just run a very long cable (in a large building)
capable of carrying the current required and have to live with the
voltage drop. Or is any voltage drop just a few volts as you suspect,
so the point is mute.

Kind of thing.



Gareth.

I haven't looked it up properly but in the design of fixed installations
you are not supposed to have more than a 4% voltage drop from the point
of supply. So whilst 6mm cable will easily carry 32A, once you go over
a certain length you would need to go up to 10mm to comply with the regs.

http://www.tlc-direct.co.uk/Technica...ltageDrop.html

--
Tim Phipps



Thanks. Then from my calculations the maximum legal drop for any
installation should be 13.6% from 240v - 207v and a bit, not including
your own power distro.


Gareth.



Um, actually I think that's a bit innacurate as the 4% will be calculated
for the power loss at 240v or even 254v? Close enough though.


Gareth.

Peavey XR 886, 1997, mixer amp
 

gareth magennis wrote:

"Tim Phipps" wrote
gareth magennis wrote:


I was just curious, knowing nothing really about wiring regulations.

If the regulations require heavier cable for longer runs to prevent
voltage drop, then is there some kind of formula with voltage drop
limits? Or can you just run a very long cable (in a large building)
capable of carrying the current required and have to live with the
voltage drop. Or is any voltage drop just a few volts as you suspect, so
the point is mute.


I haven't looked it up properly but in the design of fixed installations
you are not supposed to have more than a 4% voltage drop from the point of
supply. So whilst 6mm cable will easily carry 32A, once you go over a
certain length you would need to go up to 10mm to comply with the regs.

http://www.tlc-direct.co.uk/Technica...ltageDrop.html


Thanks. Then from my calculations the maximum legal drop for any
installation should be 13.6% from 240v - 207v and a bit, not including
your own power distro.

Hah ! 230V -10%. That's what I test kit at when doing low voltage dropout tests.

Graham