DIYbanter - View Single Post

) said...

But, Im confused about the amperage marking on the middle tab; I see
that most say 30A. Does that mean the each pole from that circuit
breaker can handle up to 30A each pole? 30 + 30 = 60A total? or is the
amps on each hot leg split into two; 15 amps each pole; 15 + 15 = 30A?

Overcurrent protection is placed on the hot side of a circuit, so with
120V circuits, there is only a single pole breaker for the single hot.

On a 240V circuit, you get 120 volts (relative to the neutral) per
hot (from separate legs). The current that goes through one returns
through the other. Overcurrent protection is needed on BOTH hots and
must be rated the same because it is the SAME current that passes through
both.

Since the voltage is doubled, even though the current is the same, the
POWER that can be provided by the circuit is doubled.

A neutral conductor is only needed on a 240V circuit if there are loads
that require only 120V on the circuit. In those cases, the neutral will
carry the DIFFERENCE between the current in each hot. (e.g.: if one hot
had a current of 10A and the other had 9A, the neutral would be carrying
the 1A difference).

Why don't wire manufactures insulate the bare ground wire inside romex
cables?

Why bother? There is really no safety issue as it only serves to bond
metal chassis and boxes to ground. It will carry a current in fault
situations, but no greater than the overcurrent protection on the circuit.

However, in the case of those ORANGE outlets, the ground pin on the
receptacle is ISOLATED from the bare ground that the box is bonded by.
A separate INSULATED ground conductor is needed to bond the ground pin
to the grounding bus in the panel. Often the red conductor of a 3-wire
cable is used for this purpose.

--
Calvin Henry-Cotnam
"I really think Canada should get over to Iraq as quickly as possible"
- Paul Martin - April 30, 2003
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