[Amps] 4 wire 240VAC service? What to do now?

[Jim Thomson]

Date: Mon, 04 Apr 2011 15:49:30 -0600
From: Doug Renwick <ve5ra at sasktel.net>
Subject: Re: [Amps] 4 wire 240VAC service? What to do now?


I looked at my Federal Pioneer sub panel and I do not see a neutral to
enclosure (ground)  bonding screw or any where a screw has been removed.

Doug

### That's  cuz they don't use a bonding screw..at least not in Canada.  If you look closely
at any main 100/200A panel.... you will see there is a place to install an offset piece of
copper buss bar.  They typ look sorta like  1/2  of a swastika.    Goes from one end of the
floating neutral buss  to metal case.   The bozo who installed the main 200A panel  for the previous 
owner had left the buss bar  strap..out of the circuit....and sitting at the bottom of the new
200A main pane!  The  4 x screws  for the 200A breaker were all semi loose too...so I cleaned
up the entire panel...and checked ALL the various connections..including all breakers. I'm wondering if the
contractor who did the work obtained a permit..or not.  In a lot of cases, the electrical inspector never shows up
to check the work of contractors.... too busy, and too few inspector's.     

## I later added a 100A  sub panel....and of course the bonding strap  between neutral buss  and metal
casing is NOT used  on any sub-panel.    The 4th wire [ green] is to handle FAULT current only..hence
the electrical code states that the neutral to metal casing strap must be removed on any sub-panel. 

## That shorting strap is installed with 2 x heavy duty tapped holes and mating screws. 

##  OK..now if your sub panel is a real small one like a 20-60A panel.... it may well  not have provisions
for the bonding strap....since it would never be used  as a main entrance panel .   The smallest service
we can have in a home, for a main panel here in town is 60A.  My sister has a 60A main panel..but her home
is pretty old.  Mine is 1953 vintage..and  had a 70A panel.  It was upgraded to 200A just before I bought it in 1997.  

##  You can usually find the info on the manufacture's website.  Sometimes the bonding strap is in the middle section of the
floating neutral buss.   The tapped holes may well be  buried under a myriad of existing wirings, but it will be there.

##  I did notice that on the big 200A  panels....that depending on which province you are in, each province  will have
different max quantities  of the smaller breaker's allowed in the 200A panel.  In some cases, the outer cover is  made  with solid steel 
where the typ 'knock outs' are located......so there is no way to install additional breakers beyond the max limit. 

## The panels to avoid are the 'stab-lock'  variety.   A dumb design ..and dangerous at best.  One side of each individual
breaker ends up making a lousy connection. 

later.... Jim   VE7RF