Subject: Re: [Shop-talk] Electrical safety question (and Alaska local question)

From: MattMahony <[email-masked]>
Date: Thu, 24 Jul 2014 06:54:28 -0700

Eric;

The problem is that you are supplying two branch circuits (in the 
trailer) from a single branch circuit (the duplex receptacle). Your 
total available amperage is limited by the single branch circuit and it 
will be easier to trip the single breaker feeding that branch. This 
setup is a violation of the NEC but it wouldn't be unsafe as long as it 
is properly grounded.

It truly would be more convinient in the long run to supply it with a 
240V 15A circuit. Most generators have this output capacity.  A 12 Ga, 3 
wire with ground cable is not that expensive and would make your setup 
portable.

Matt

On 7/24/2014 6:26 AM, [email-masked] wrote:
> OK, so I picked up a used 'construction office' trailer this weekend.  The
> idea for me is to use it as a mobile studio for the SO to paint and do
> other crafts.
>
> The trailer was already wired for 240v.  Inside the trailer each leg
> becomes a separate 15 amp circuit (on their own breaker.)
>
> Here is what I did temporarily to get power to the trailer (and what I
> want to do permanently if it is safe.)
>
> I spliced the 240v line into two separate 120 volt lines.  (splitting the
> common and ground into each plug.)
>
> This way, I just need to plug both plugs into a duplex receptacle (much
> more common) and I don't need to have a dedicated 240v outlet to use the
> trailer.
>
> There are no 240v circuits inside the trailer that would require 2
> separate 'legs'.
>
> Is this safe?  (or 'safe enough')
>
> The power is just for the lights, and a fan, radio, glue gun or something
> like that.  I'm not running any heavy duty equipment from it.  (I may add
> a TV or video game cabinet at some point.)
>
> Am I crazy?
>
> Side note-  I'll be in Anchorage, AK next week.  Anyone here up in that
> part of the woods?  I'll buy lunch.
>
> Eric P
> "Be as beneficent as the sun or the sea, but if your rights as a rational
> being are trenched on, die on the first inch of your territory." Ralph
> Waldo Emerson
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---

From: Mark Andy <[email-masked]>
Date: Thu, 24 Jul 2014 10:48:00 -0400

Howdy,

If I'm reading it correctly, you're doing basically what lots of motorhomes
do.  Ours has a 240v 50A power connection.  There are no 240vac loads in
the coach.  Adapters are used to combine the 240vac hot legs together,
sharing a common neutral and ground, to enable you to plug into a 110vac
line.  That means that in the coach what were separate 110vac runs now
share a common hot wire, but aside from that combining those loads on the
supply circuit (which almost certainly means there's less power available),
there's no negative effect.

Mark

On Thu, Jul 24, 2014 at 9:26 AM, <[email-masked]> wrote:

> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/shop-talk/[email-masked]

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---

From: "Karl Vacek" <[email-masked]>
Date: Thu, 24 Jul 2014 09:50:18 -0500

Another consideration is that internally to the trailer wiring the
manufacturer might have shared neutrals, which is fine as long as circuits
sharing a neutral are on opposite phases.  Even if you plug each of your
split-circuit plugs into separate circuits, if they're on the same phase (in
the breaker box), any shared neutrals in the trailer could be overloaded.
This is dependent upon the total load used on both circuits.

Karl

-----Original Message-----
From: Shop-talk [mailto:[email-masked]] On Behalf Of
MattMahony
Sent: Thursday, July 24, 2014 8:54 AM
To: [email-masked]
Subject: Re: [Shop-talk] Electrical safety question (and Alaska local
question)

Eric;

The problem is that you are supplying two branch circuits (in the
trailer) from a single branch circuit (the duplex receptacle). Your total
available amperage is limited by the single branch circuit and it will be
easier to trip the single breaker feeding that branch. This setup is a
violation of the NEC but it wouldn't be unsafe as long as it is properly
grounded.

It truly would be more convinient in the long run to supply it with a 240V
15A circuit. Most generators have this output capacity.  A 12 Ga, 3 wire
with ground cable is not that expensive and would make your setup portable.

Matt

On 7/24/2014 6:26 AM, [email-masked] wrote:
> OK, so I picked up a used 'construction office' trailer this weekend.  
> The idea for me is to use it as a mobile studio for the SO to paint 
> and do other crafts.
>
> I spliced the 240v line into two separate 120 volt lines.  (splitting 
> the common and ground into each plug.)
>
> This way, I just need to plug both plugs into a duplex receptacle 
> (much more common) and I don't need to have a dedicated 240v outlet to 
> use the trailer.
>
> The power is just for the lights, and a fan, radio, glue gun or 
> something like that.  I'm not running any heavy duty equipment from 
> it.  (I may add a TV or video game cabinet at some point.)
>
> Am I crazy?
>
> Side note-  I'll be in Anchorage, AK next week.  Anyone here up in 
> that part of the woods?  I'll buy lunch.
>
> Eric P
> "Be as beneficent as the sun or the sea, but if your rights as a 
> rational being are trenched on, die on the first inch of your 
> territory." Ralph Waldo Emerson 
> Donate: http://www.team.net/donate.html Suggested annual donation  
> $12.96
> http://autox.team.net/mailman/options/shop-talk/[email-masked]

[email-masked]
Archive: http://www.team.net/archive
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