Flexible cable for generator backfeed use?

[Richard]

I've been using 10/3 romex to go from my generator to the main house panel, but
it's a pain to coil up and roll out when I need it.

I'm thinking about replacing it with something like welders cable, but since
that's a fine threaded copper wire, I don't know if I need to go larger or what?

I'm only using about 50'.

Any suggestions are appreciated.

 

[Dale Farmer]

I've been using 10/3 romex to go from my generator to the main house panel, but
it's a pain to coil up and roll out when I need it.

I'm thinking about replacing it with something like welders cable, but since
that's a fine threaded copper wire, I don't know if I need to go larger or what?

I'm only using about 50'.

Any suggestions are appreciated.

SO 12/3 cable is readily available at anyplace that sells decent extension
cords. fifty feet is good for about 13 amps at 120 volts, without actually
going and looking up the tables. Small generator. May be easier to just
run the extension cable direct to the things you are powering at the time.

--Dale

 

[Vaughn Simon]

I've been using 10/3 romex to go from my generator to the main house panel, but
it's a pain to coil up and roll out when I need it.

I'm thinking about replacing it with something like welders cable, but since
that's a fine threaded copper wire, I don't know if I need to go larger or what?

I'm only using about 50'.

Any suggestions are appreciated.

Use #10 SO cable http://www.alphawire.com/pages/312.cfm possibly
available at your local Home Depot.

Caution! Do not use that b@ackfeed word here, there are flamers hiding
in the wings ready to righteously set you straight.

Vaughn

 

[Richard]

SO 12/3 cable is readily available at anyplace that sells decent extension
cords. fifty feet is good for about 13 amps at 120 volts, without actually
going and looking up the tables. Small generator. May be easier to just
run the extension cable direct to the things you are powering at the time.

Not an option.

The generator feeds the house and that's how I'm going to use it. I'm
certainly not going to start moving and unplugging equipment every time we
lose power.

It's a 240V 30A output on the generator, so that requires #10 solid copper.

10 is a very cumbersome wire to roll up and work with, so I'd rather get
something flexible.

 

[Richard]

Use #10 SO cable http://www.alphawire.com/pages/312.cfm possibly
available at your local Home Depot.

Thanks. I'll check that out.

Caution! Do not use that b@ackfeed word here, there are flamers hiding
in the wings ready to righteously set you straight.

*shrug* Let them flame/complain/correct/whatever. I know what I'm doing
is safe and I'm going to continue to use it this way.

 

[Dale Farmer]

Not an option.

The generator feeds the house and that's how I'm going to use it. I'm
certainly not going to start moving and unplugging equipment every time we
lose power.

It's a 240V 30A output on the generator, so that requires #10 solid copper.

Wire gauge is measured by the amount of copper cross section. 10 gauge
stranded and ten gauge solid have the same amount of copper in them, the
stranded is just slightly larger in diameter because of the air gaps between
the strands. 10/3 SO cable is readily available at Home Depot. I would
recommend that you upgrade to 8 gauge though, if you are drawing the full
thirty amps, that cable is going to get a bit toasty.
Welding cable used for temporary power applications was disallowed
in a recent edition of the national electrical code. ( Assuming you are in
the US. ) I'm not sure why.

10 is a very cumbersome wire to roll up and work with, so I'd rather get
something flexible.

SOrry, I misread the number 10 as 12. THat's what I get for doing email
before the caffiene kicks in.
The correct way to do this is to get one of those generator switch over panels,
that have an L14-30 male connector on them. Then just get the cable, and
a pair of the connectors to make up an extension cord for your generator. You
can also get an external box permanently wired up to the outside with the
L14 connector, so you don't have to run the cable in through a window or
door left open. May have to get a locally licensed electrician to do the work,
modulo your local electrical code. Positive disconnecting means that has
no possibility of connecting your generator to the utility power feed are
often required by law, due to the non-trivial number of utility workers who
got electrocuted by home generators back feeding the street after power
failures.

--Dale

 

[Mark]

The AWG wire ratings are based on the actual copper area in the cable.
It doesnt matter whether it is fine strands or not.

That is correct that gauge is gauge. I think the OP is asking if there is
a different AWG requirement for amperage loads based on if the wire is
solid or stranded.

I do recall something about people who build their own hot-rods and reloate
their battery to the rear for better traction. They use the same AWG (4 I
believe) welders cable to do this since it's easier and more flexible. If
they have to crank the car too long for some reason, you risk heating the
cable too much and weaken the sheathing.

If NEC says gauge is gauge and solid vs. stranded doesn't matter, I guess
there is no issue.

 

[Vaughn]

due to the non-trivial number of utility workers who
got electrocuted by home generators back feeding the street after power
failures.

Don't say I didn't warn you Richard! ;-)

Vaughn

 

[[email protected]]

Wire gauge is measured by the amount of copper cross section. 10 gauge
stranded and ten gauge solid have the same amount of copper in them, the
stranded is just slightly larger in diameter because of the air gaps between
the strands. 10/3 SO cable is readily available at Home Depot. I would
recommend that you upgrade to 8 gauge though, if you are drawing the full
thirty amps, that cable is going to get a bit toasty.
Welding cable used for temporary power applications was disallowed
in a recent edition of the national electrical code. ( Assuming you are in
the US. ) I'm not sure why.

Likely because the insulation is designed for lower voltage. (and it
is single conductor)

 

[Michelle P]

8/3 SJ
8 gauge 3 conductor Single Jacket. Flexible good up to 50 or so amps.
Expensive and heavy but well worth it.
Michelle

 

[Dave Hinz]

Don't say I didn't warn you Richard! ;-)

Well, (a) it's a valid concern, and (b) that's hardly a flame.

 

[Richard]

Well, (a) it's a valid concern, and (b) that's hardly a flame.

Please explain to me how I can zap a utility worker with the main
disconnected....

Bottom line is: What I'm doing is 100% legal and safe. End of discussion on
this "issue".

 

[Richard]

8/3 SJ
8 gauge 3 conductor Single Jacket. Flexible good up to 50 or so amps.
Expensive and heavy but well worth it.
Michelle

Thanks Michelle. I'll take a look at that as well. This is the weekend to
button it all up.

 

[Dave Hinz]

Please explain to me how I can zap a utility worker with the main
disconnected....

If you never screw up, they'll be fine. Their life is in your hands.
Don't screw up.

Bottom line is: What I'm doing is 100% legal and safe. End of discussion on
this "issue".

If you installed a UL listed transfer switch, then you'd be 100% safe.
As it is, you're less than 100% safe. Actually, _you_ are 100% safe,
it's the other person who pays if you blow it.

I stand by my statement that (a) it's a valid concern, and (b) this
isn't a flame.

 

[Vaughn Simon]

I do recall something about people who build their own hot-rods and reloate
their battery to the rear for better traction. They use the same AWG (4 I
believe) welders cable to do this since it's easier and more flexible. If
they have to crank the car too long for some reason, you risk heating the
cable too much and weaken the sheathing.

Actually, if you dig into the NEC you will find diffirent ampacities
listed for different cables of the same guage. This is because some types
of insulation can take higher heat without damaege. The NEC is a safety
code. As such, it tends to ignore effiiciency (as well as other mundane
practical matters).

Vaughn

 

[[email protected]]

More surface area is better; that is what I have heard. I use 4/0
welding cables from my battery bank to my inverter. I was using battery
cable before and the wire would get warm when charging at 30 amps AC.
Using the welding cable, I have no detectable heat in the lines to my
battery bank.

I may know nothing about the physics, but I have heard from more than
one person that the more surface area, the better the conductor.

Jamey

This is true in the case of high frequency AC. With DC it is TOTALLY
irrelevent. With 60 hz AC the effect is so minimal as to be almost
impossible to measure.

-----Original Message-----
From: Mark [mailto:[email protected]]
Posted At: Thursday, August 18, 2005 1:38 PM
Posted To: alt.energy.homepower
Conversation: Flexible cable for generator backfeed use?
Subject: Re: Flexible cable for generator backfeed use?

The AWG wire ratings are based on the actual copper area in the cable.
It doesnt matter whether it is fine strands or not.

That is correct that gauge is gauge. I think the OP is asking if there
is
a different AWG requirement for amperage loads based on if the wire is
solid or stranded.

I do recall something about people who build their own hot-rods and
reloate
their battery to the rear for better traction. They use the same AWG (4
I
believe) welders cable to do this since it's easier and more flexible.
If
they have to crank the car too long for some reason, you risk heating
the
cable too much and weaken the sheathing.

If NEC says gauge is gauge and solid vs. stranded doesn't matter, I
guess
there is no issue.

 

[Me]

More surface area is better; that is what I have heard. I use 4/0
welding cables from my battery bank to my inverter. I was using battery
cable before and the wire would get warm when charging at 30 amps AC.
Using the welding cable, I have no detectable heat in the lines to my
battery bank.

I may know nothing about the physics, but I have heard from more than
one person that the more surface area, the better the conductor.

Jamey

Only true for AC Power as AC power runs on the surface of the conductor,
whereas DC Runs thru the total crosssection of the conductor.

Me

 

[Me]

Bottom line is: What I'm doing is 100% legal and safe. End of discussion on
this "issue".

Actually, No, your not 100% Legal, or Safe if you live in a US State
that has adopted the NEC as part of it's State Statutes, as part of
local building codes.........

Me

 

[Jim Baber]

Likely because the insulation is designed for lower voltage. (and it
is single conductor)

I am sure this is one of those city 'legends' we have all heard about.
I suspect the real reason is that the utilities don't want uncontrolled
generators on the grid even when it is operational. As far as
electrocuting utility workers, there would be such a hugh load (the
entire grid) on your generator when it was supplying power to an
otherwise unpowered grid, it will see that load as a dead short circuit
and trip its own circuit breakers. It sure as he... won't be able to
electrocute anybody, but you will burn your generator up if it's circuit
breakers don't function very quickly.

 

[RF Dude]

I clipped the comments out of Richard's messages and pasted them below.
Some appear contradictory. And when valid feedback is provided, albeit
sometimes not with a full explaination, there are interesting responses from
Richard.

It is exactly that attitude that wins Darwin awards or gets you sued if you
caused someone else grief. The b-a-c-k-f-e-e-d issue is real. Even
normally intelligent people forget to open the mains disconnect in a power
failure when trying to feed their house thru a 30A dryer plug or equivalent.
Thats why the electrical code requires a physical interlock to ensure that
when the your generator is supplying power, the utility feed is
disconnected.

RFdude

The generator feeds the house and that's how I'm going to use it. I'm
certainly not going to start moving and unplugging equipment every time we
lose power.