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[OM] Re: [OT] More OT electrical advice needed

Subject: [OM] Re: [OT] More OT electrical advice needed
From: Moose <olymoose@xxxxxxxxx>
Date: Wed, 17 May 2006 11:14:48 -0700
Chuck Norcutt wrote:
> Sometime after I moved into this house I noticed that the wiring of the 
> air conditioner's air handler unit in the basement had not been 
> completed properly.  (probably due to a dispute with the builder who was 
> going bankrupt and likely paying off the local building inspectors)
>
> In any case, the air handler has a 230v line coming in inside a conduit 
> which runs into a junction box.  The 230v stuff arrives at an on/off 
> switch whose outputs continue into the air handler to run the motor but 
> also divide off 115v into a single socket outlet to operate a small 
> condensate pump (since there is no floor drain).
>   
My advice is neither professional or to be relied on to do any 
electrical work. It may, however be relied on to decide not to do it 
yourself, if it points in that direction.

One crucial thing is not made clear in your description, and could 
indicate a serious danger!

A 230v domestic circuit uses only three wires, one for each leg of the 
230v and one ground. A 115v circuit also uses three wires, one hot, one 
neutral and one ground. SO, if 115v is tapped off a three wire 230v 
circuit, it can only be between one side of the 230v line and ground. 
USING GROUND IN PLACE OF NEUTRAL IS NEITHER LEGAL NOR SAFE!!!!

SO - unless there are four wires coming in from the breaker box AND you 
can confirm which is ground and which is neutral, it is simply not safe 
and needs repair, not just tidying up into an enclosed box. Normally, 
wire colors would tell you what's going on, but where there is already a 
kludge, that's not reliable. Where they are coming from also needs to be 
confirmed.

I don't know the code anymore, but I suspect you can only meet code in 
this situation with a separately fused hot wire in addition to the 
neutral wire for the 115v. The active components of the two circuits 
need to be separate, but the ground may be shared. Code or not, I 
wouldn't do it any other way. You don't want different currents going 
through the two legs and ganged breakers of a proper 230v line.

Now it is clear why a builder under financial pressure might jury rig 
the unplanned 115v needed for the pump. Doing it right would mean 
pulling two more wires and adding a circuit breaker or tapping off 
another existing 115v circuit. The box was probably left 
uncovered/dangling because whoever did the tap intended to come back and 
finish the job, but never did because of the builder's problems. Or 
maybe the electrician is blameless and the builder did the kludge after 
inspection. And whoever did it left it dangling as a warning to whoever 
dealt with it later that it really was unfinished.

Be careful, buddy!

Moose

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