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Protection of branch service

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Dave M.

Jan 1, 1970
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At a garage with an antiquated electrical service, a buddy wired an old 2
pole switch box ( I hope with fusing ) to a disconnect that is just after
the watt hour meter. The switch box supplies a 240 volt compressor. I don't
know if the main disconnect has fusing in it to protect the Romex from the
switch. So, my concern is that there is no protection for that short Romex.

Aren't branch services ( panels or boxes ) supposed to have conductor
protection at the source of power?

I run branch services off a two pole breaker rated to protect the
conductors leading to the panel.

Dave M.
 
D

Dave M.

Jan 1, 1970
0
Gfretwell said:
That is a feeder tap. see 240.21(B)(1)


It should


It all depends on the size and length of the tap, how it is protected and the
size of the O/C device in the disconnect. Since you said Romex I say no.

If the extra box is adjacent to the main disconnect(less than 3' total
conductor length), connected in conduit and good for at least 10% of the main
disconnect amps it is probably OK.

That means a 20a sub-panel (what this is) tapped with < 3' of 12ga wire in
conduit and meeting the other grounding rules it should be OK.
The only other question is how did he make the connection in the disconnect???
If he doubled up the conductor in the breaker lug that is probably not OK. I
haven't seen a breaker in these sizes that accept 2 conductors. There are
tapping devices that would make this OK tho.


The conductor is about a foot between the switch box and the main cut-off
and is not protected by conduit and it would have to endure at least three
times its rated capacity if a short develops. I assume he stacked the
conductors. It looks like it is not code because of the lack of conduit,
right? I didn't know that any conductor could do without protection of it's
rated load. NEC or not, I will always use a breaker to protect any conductor
of any length, or am I being ridiculous?

Dave M.
 
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daestrom

Jan 1, 1970
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Dave M. said:
The conductor is about a foot between the switch box and the main cut-off
and is not protected by conduit and it would have to endure at least three
times its rated capacity if a short develops. I assume he stacked the
conductors. It looks like it is not code because of the lack of conduit,
right? I didn't know that any conductor could do without protection of it's
rated load. NEC or not, I will always use a breaker to protect any conductor
of any length, or am I being ridiculous?

While I'm not a code guru, I do know this. NEC is a *minimum*. If the
feeder is short, protection is not *required*. But protection is obviously
better than without.

Ridiculous, no. But some tightwad customer may not like paying for it. But
then, some customer's don't like paying for anything, so...

daestrom
 
D

Dave M.

Jan 1, 1970
0
Gfretwell said:
That is covered in the "tap" rules. The assumption is you are only protecting
against a short since the downstream O/C device protects against overload. By
putting this short tap in conduit you are assuming that it is protected from
damage, minimizing the potential of a short and containing the fire if the
short occurs.
I would say if he slipped this through a short piece of conduit it would be
"hold your nose" legal. The other issues of the double lugging and whether his
grounding is up to snuff should be looked at too.

Well, chances are nothing will go wrong. I just don't like it.

Dave M.
 
D

Dave M.

Jan 1, 1970
0
daestrom said:
While I'm not a code guru, I do know this. NEC is a *minimum*. If the
feeder is short, protection is not *required*. But protection is obviously
better than without.

Ridiculous, no. But some tightwad customer may not like paying for it. But
then, some customer's don't like paying for anything, so...

Oh! This customer IS a tightwad!

Dave M.
 
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