Electrical Engineering - installing a 30 amp circuit

Author

installing a 30 amp circuit

ejsimcox

2007-07-09, 5:25 pm

Group,

I am installing a computer equipment rack in my home office. The Power
strip (PDU) that I want to use is the Geist VRTDN200-10310TL. It
terminates in a NEMA L5-30P. The specs on the PDU are 30 Amps, 125V,
3750 Watts, 2 x 15 Amp circuits, 2 15 Amp internal circuit breakers,
10 duplex recepticles per circuit (total of 20).

Here is a link to the PDU's specs:

http://www.geistmfg.com/dzapps/dbza...mfg&pItemID=158

The question is: do I need to install a 2 pole 30 Amp breaker or a
single pole 30 Amp circuit? The specs on the PDU are 125V but the
cable is 10/3 and the connector is L5-30P. Isn't that a 2 pole
configuration? If I need a single pole configuration, how do I wire
the L5-30R?

Thanks,
Ed

Palindrome

2007-07-09, 5:25 pm

ejsimcox wrote:
> Group,
>
> I am installing a computer equipment rack in my home office. The Power
> strip (PDU) that I want to use is the Geist VRTDN200-10310TL. It
> terminates in a NEMA L5-30P. The specs on the PDU are 30 Amps, 125V,
> 3750 Watts, 2 x 15 Amp circuits, 2 15 Amp internal circuit breakers,
> 10 duplex recepticles per circuit (total of 20).
>
> Here is a link to the PDU's specs:
>
> http://www.geistmfg.com/dzapps/dbza...mfg&pItemID=158
>
> The question is: do I need to install a 2 pole 30 Amp breaker or a
> single pole 30 Amp circuit? The specs on the PDU are 125V but the
> cable is 10/3 and the connector is L5-30P. Isn't that a 2 pole
> configuration? If I need a single pole configuration, how do I wire
> the L5-30R?
>

No need for any of that. Run a couple of bare wires straight from the
PDU through a couple of holes in the wall. Space the holes a few inches
apart, for safety. Run the wires up to the nearest overhead cables and
wind them around the conductors for two or three turns. Bind them in
place with string. Whilst you can use a ladder to get to the cables,
backing a truck up underneath is quicker. That should do it! Whilst you
are up there, you might as well tap off some cable tv.

Of course, if you don't live in Haiti, your local accepted practice may
be different. In which case, you may like to say where you *are*
located...this *is* an international group.

--
Sue

Pete C.

2007-07-09, 5:25 pm

ejsimcox wrote:
>
> Group,
>
> I am installing a computer equipment rack in my home office. The Power
> strip (PDU) that I want to use is the Geist VRTDN200-10310TL. It
> terminates in a NEMA L5-30P. The specs on the PDU are 30 Amps, 125V,
> 3750 Watts, 2 x 15 Amp circuits, 2 15 Amp internal circuit breakers,
> 10 duplex recepticles per circuit (total of 20).
>
> Here is a link to the PDU's specs:
>
> http://www.geistmfg.com/dzapps/dbza...mfg&pItemID=158
>
> The question is: do I need to install a 2 pole 30 Amp breaker or a
> single pole 30 Amp circuit? The specs on the PDU are 125V but the
> cable is 10/3 and the connector is L5-30P. Isn't that a 2 pole
> configuration? If I need a single pole configuration, how do I wire
> the L5-30R?
>
> Thanks,
> Ed

L5-30 is a 125V configuration (hot - brass screw, neutral - silver
colored screw, ground - green colored screw), L6-30 is the 250V
configuration. Unless your home office setup is absurdly large, remove
the L5-30 plug and replace with a 5-20 or 5-15 "normal" household plug
and plug into a normal outlet. Highly unlikely your home office computer
setup will draw in excess of 15A.

Chris Lewis

2007-07-09, 5:25 pm

According to Pete C. <aux3.DOH.4@snet.net>:
> ejsimcox wrote:
>
> L5-30 is a 125V configuration (hot - brass screw, neutral - silver
> colored screw, ground - green colored screw), L6-30 is the 250V
> configuration. Unless your home office setup is absurdly large, remove
> the L5-30 plug and replace with a 5-20 or 5-15 "normal" household plug
> and plug into a normal outlet. Highly unlikely your home office computer
> setup will draw in excess of 15A.

Perhaps what the OP is getting confused about is the fact that the
powercord is "/3". Flexible cord designations _include_ the insulated
ground in the "/n", whereas solid building wire with bare grounds
do not. In other words, 10/3 flex cord has three insulated wires,
one used as a ground. "10/3 wg" (we don't use "wg" designations
in Canada, all building wire has bare grounds) solid building wire
has four conductors, one bare.

In other words, 10/3 flexible cord is what you use with a single pole
circuit with a ground. 10/2 flexible cord doesn't have a ground.
10/3 could also be used in a 240V circuit _without_ neutral. But not
two pole (split) 120/240V like a modern stove/dryer circuit.

I've seen "home systems" with power requirements in excess of 20A (especially
when you factor in laser printers), so the OP should check his actual
requirements. If it's <= 16Aish, I'd recommend replacing the power cord
with a premade 14/3 or 12/3 cord and plug assembly (eg: cut the end
off a short 3 prong extension cord of the appropriate rating - probably
won't cost anymore than a decent 5-20 plug will). It'll then work
off an ordinary 15A or 20A circuit.

Don't futz around trying to make 10ga wire work on a 5-20 plug. It's hard
enough as it is with the right wire, let alone overly large stuff.

If he does need > 16Aish, he needs to wire a circuit with a single pole
30A breaker and 10/2 (with ground ;-) building wire.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

Terry

2007-07-09, 5:25 pm

On Mon, 09 Jul 2007 19:47:15 -0000, ejsimcox <ejsimcox@hotmail.com>
wrote:

>Group,
>
>I am installing a computer equipment rack in my home office. The Power
>strip (PDU) that I want to use is the Geist VRTDN200-10310TL. It
>terminates in a NEMA L5-30P. The specs on the PDU are 30 Amps, 125V,
>3750 Watts, 2 x 15 Amp circuits, 2 15 Amp internal circuit breakers,
>10 duplex recepticles per circuit (total of 20).
>
>Here is a link to the PDU's specs:
>
>http://www.geistmfg.com/dzapps/dbza...mfg&pItemID=158
>
>The question is: do I need to install a 2 pole 30 Amp breaker or a
>single pole 30 Amp circuit? The specs on the PDU are 125V but the
>cable is 10/3 and the connector is L5-30P. Isn't that a 2 pole
>configuration? If I need a single pole configuration, how do I wire
>the L5-30R?
>
>Thanks,
>Ed

http://www.passandseymour.com/produ...ct.html?c=L530R

Use a 30A single pole breaker.

2007-07-09, 5:25 pm

On Mon, 09 Jul 2007 20:43:28 -0000, clewis@nortelnetworks.com (Chris
Lewis) wrote:

>
>I've seen "home systems" with power requirements in excess of 20A (especially
>when you factor in laser printers), so the OP should check his actual
>requirements.

Absolutely.

>If it's <= 16Aish, I'd recommend replacing the power cord
>with a premade 14/3 or 12/3 cord and plug assembly (eg: cut the end
>off a short 3 prong extension cord of the appropriate rating

Good idea, but I'd leave at least 6 or 8 inches of wire on the female
end of the extension cord. Then you can put a plug on that and have
another short extension cord. I'd even buy a longer extension cord
maybe, because they charge the most for the ends and very little for
extra wire in between.

>- probably
>won't cost anymore than a decent 5-20 plug will). It'll then work
>off an ordinary 15A or 20A circuit.

Paul Hovnanian P.E.

2007-07-09, 8:25 pm

Palindrome wrote:
>
> ejsimcox wrote:
>
> No need for any of that. Run a couple of bare wires straight from the
> PDU through a couple of holes in the wall. Space the holes a few inches
> apart, for safety. Run the wires up to the nearest overhead cables and
> wind them around the conductors for two or three turns. Bind them in
> place with string. Whilst you can use a ladder to get to the cables,
> backing a truck up underneath is quicker. That should do it! Whilst you
> are up there, you might as well tap off some cable tv.
>
> Of course, if you don't live in Haiti, your local accepted practice may
> be different. In which case, you may like to say where you *are*
> located...this *is* an international group.

Well, we have underground distribution where I live. So the advice about
the ladder and/or pickup truck wouldn't apply. We estimate the location
of the buried feeder and go to work with a pickaxe. The bit about
wrapping around the cables is OK once you've scraped off the insulation
with a couple of good swings.

Note to humor impared: Don't try this at home, kids.

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
"Grant me the strength to change what I can, the ability to accept
what I can't, and the incapacity to tell the difference."
-- Calvin (of Calvin and Hobbes)

Doug Miller

2007-07-10, 9:25 am

In article <8xwki.524608$dg3.420127@fe10.news.easynews.com>, me@palindr0me.plus.com.invalid wrote:
>ejsimcox wrote:

[snip][color=darkred]
>
>Of course, if you don't live in Haiti, your local accepted practice may
>be different. In which case, you may like to say where you *are*
>located...this *is* an international group.

"NEMA" = National Electrical Manufacturers Association, a United States trade
group. It's a pretty fair assumption the poster is located in North America.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Doug Miller

2007-07-10, 9:25 am

In article <1184010435.792489.142200@k79g2000hse.googlegroups.com>, ejsimcox <ejsimcox@hotmail.com> wrote:
>Group,
>
>I am installing a computer equipment rack in my home office. The Power
>strip (PDU) that I want to use is the Geist VRTDN200-10310TL. It
>terminates in a NEMA L5-30P. The specs on the PDU are 30 Amps, 125V,
>3750 Watts, 2 x 15 Amp circuits, 2 15 Amp internal circuit breakers,
>10 duplex recepticles per circuit (total of 20).
>
>Here is a link to the PDU's specs:
>
>http://www.geistmfg.com/dzapps/dbza...webid=geistmfg&
>pItemID=158
>
>The question is: do I need to install a 2 pole 30 Amp breaker or a
>single pole 30 Amp circuit? The specs on the PDU are 125V but the
>cable is 10/3

Right, that's because the ground conductor is included in the count in a
cord-and-plug connection. Your 10/3 cord set is hot, neutral, and ground.

>and the connector is L5-30P. Isn't that a 2 pole
>configuration?

The NEMA 5-series connectors are 125V devices, and hence the circuits that
supply them use single-pole breakers.

Plugs and receptacles are designated as 2-pole, 3-pole, etc. to indicate the
number of current-carrying conductors in the receptacle. This is not the same
as the pole count on the breaker supplying the receptacle: the 5-30R and 6-30R
are *both* designated as "2-pole" receptacles, but the 5-30R has hot + neutral
and uses a single-pole (125V) breaker, whereas the 6-30R has two hots and uses
a double-pole (250V) breaker.

>If I need a single pole configuration, how do I wire
>the L5-30R?

Use a 30A single-pole breaker and 10/2 cable with ground -- yes, that's right,
ten-TWO cable -- connected to the receptacle thus:
- black wire to the gold screw
- wite wire to the silver screw
- green wire to the green screw

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Palindrome

2007-07-10, 9:25 am

Doug Miller wrote:
> In article <8xwki.524608$dg3.420127@fe10.news.easynews.com>, me@palindr0me.plus.com.invalid wrote:
>
>
>
>
>
> [snip]
>
>
>
> "NEMA" = National Electrical Manufacturers Association, a United States trade
> group. It's a pretty fair assumption the poster is located in North America.
>

Normally for questions involving 120v stuff, you are right that the
poster is likely to be in the US or Canada.

However, this is an international group and there is an every-present
danger that someone will be given incorrect advice because posters
assumed that the OP must be in the US..

Such connectors are widely used -in countries other than the USA and
Canada. Just because there aren't going to be many posters from those
countries posting in English, doesn't preclude the possibility...

Heavens, I even use such connectors myself, here in the UK...

--
Sue

Doug Miller

2007-07-10, 9:25 am

In article <_MKki.69229$qT.31185@fe06.news.easynews.com>, me@palindr0me.plus.com.invalid wrote:
>Such connectors are widely used -in countries other than the USA and
>Canada. Just because there aren't going to be many posters from those
>countries posting in English, doesn't preclude the possibility...
>
>Heavens, I even use such connectors myself, here in the UK...

You use NEMA connectors in the UK?? I thought your plug and receptacle
configurations didn't even remotely resemble ours.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Palindrome

2007-07-10, 9:25 am

Doug Miller wrote:
> In article <_MKki.69229$qT.31185@fe06.news.easynews.com>, me@palindr0me.plus.com.invalid wrote:
>
>
>
> You use NEMA connectors in the UK?? I thought your plug and receptacle
> configurations didn't even remotely resemble ours.
>

In parts of computer rooms, sure. The US makes some nice computer kit

- but often not with International or British power connectors, for some
strange reason...
--
Sue

phil-news-nospam@ipal.net

2007-07-12, 9:25 am

In alt.engineering.electrical ejsimcox <ejsimcox@hotmail.com> wrote:

| I am installing a computer equipment rack in my home office. The Power
| strip (PDU) that I want to use is the Geist VRTDN200-10310TL. It
| terminates in a NEMA L5-30P. The specs on the PDU are 30 Amps, 125V,
| 3750 Watts, 2 x 15 Amp circuits, 2 15 Amp internal circuit breakers,
| 10 duplex recepticles per circuit (total of 20).
|
| Here is a link to the PDU's specs:
|
| http://www.geistmfg.com/dzapps/dbza...mfg&pItemID=158
|
| The question is: do I need to install a 2 pole 30 Amp breaker or a
| single pole 30 Amp circuit? The specs on the PDU are 125V but the
| cable is 10/3 and the connector is L5-30P. Isn't that a 2 pole
| configuration? If I need a single pole configuration, how do I wire
| the L5-30R?

A NEMA L5-30P is a plug for a SINGLE POLE 125[1] volt 30 amp circuit.
So your breaker would be ONE pole 30 amp, and the wiring would be a
AWG 10 or larger (smaller number). If wired in conduit or cabled in
metallic, the wires will have colors green, black, and white. If in
non-mettalic cable, the ground wire will most likely be bare instead
of green.

The L5-30R will have connections for ground (connect with the green or
bare wire), hot/live (connect with the black wire), and neutral (connect
with the white wire).

The designation "10/3" is an example of where someone counts the ground.
This is a common source of ambiguity. Find out what insulation colors
those wires have to tell you the circuit type.

If wiring in metallic conduit/cable, it might be wise to go with an
"isolated ground" circuit. To do this you need a receptacle that has
a specific isolated ground capability (no connection between the ground
pin and the frame). The wires will include a 2nd ground wire colored
with a green/yellow stripe. This allows grounding the frame and metal
conduit separately from the receptacle ground pin (but they still meet
at the circuit source in the breaker box).

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-07-12-0849@ipal.net |
|------------------------------------/-------------------------------------|

Ben Miller

2007-07-14, 3:25 am

"Pete C." <aux3.DOH.4@snet.net> wrote in message
news:469298D4.ACCD4521@snet.net...
>
> L5-30 is a 125V configuration (hot - brass screw, neutral - silver
> colored screw, ground - green colored screw), L6-30 is the 250V
> configuration. Unless your home office setup is absurdly large, remove
> the L5-30 plug and replace with a 5-20 or 5-15 "normal" household plug
> and plug into a normal outlet. Highly unlikely your home office computer
> setup will draw in excess of 15A.

It is better not to modify the UL Listed device by putting a smaller plug on
it.
To answer the original question, use a single-pole 30A breaker. Have a
qualified electrician install the circuit.

Ben Miller

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