conduit and switch on service boxes
not satisfactory for shielding, and should not be used.
The shield on all wiring should be grounded at in-
(f) D
O the conduit couplings make good elec-
trical contact?
tervals of 50 feet and good electrical bonding be-
Note. If in doubt on (d), (e) and (f) use bonding.
(g) Is the conduit system grounded at a point
This shielding requirement applies to all wiring, in-
at least 50 feet from the welder?
cluding telephone, intercommunication, signal and
(h) Have the unshielded power and light wires
control, and incidental service. The foregoing proce-
in the H.F.I. Zone been placed in grounded shields
dures shall apply even if:
or been relocated outside the zone?
(a) The welding area is not a fixed location.
(i) Is the conduit run complete (without any
(b) There are exposed wires off the premises
gap) in the H.F.I. Zone?
within 50 feet of the welding area.
(4) Placement of welding leads. Direct radiation
(j) Have all large metallic objects and any long
guy or supporting wires in the H.F.I. Zone been
from the welding leads, although very pronounced,
grounded?
decreases rapidly within distance from the leads.
(k) Is the welder case connected to the work
terminal of the secondary?
from the welding leads by adhering to the following
(l) Is the wire used for this connection of suffi-
cient size?
(a) Keep the welding leads as short as possible.
(m) Is the work terminal connected to a good
(b) Keep the electrode lead and ground or work
electrical ground?
lead as close together as possible (3/4 inch to 1 inch
(n) Is this cable as short as possible?
apart) and on the floor or placed on a suitable board.
(o) Are the spark gaps set at 0.008 inches?
(5) Adjustment of spark gap. Spark gap settings
(P) Are all service or access doors closed?
shall be maintained at the minimum separation con-
(q) Are the welding leads as short as possible?
sistent with satisfactory welding results. The recom-
(Do not exceed 25 feet in length).
mended maximum gap setting is 0.008 inches. The
(r) Are the welding leads on the floor or placed
wider the spark gap setting, the greater is the power
on a suitable board?
which is radiated.
(s) Are the welding leads approximately 3/4 to
(6) Installation in metal buildings. It is frequent-
1 inch apart?
ly thought that operation of high frequency stabi-
(t) Have you checked so that no external power
lized arc welding equipment in metallic buildings
or telephone lines off the premises are within this
w i l l completely eliminate troublesome radiation.
zone?
This, however, is a false assumption. A metallic
(u) Are the connections to the ground clean
building structure, if properly grounded, may serve
and tight?
to reduce radiation from the weld zone but will have
(v) If operated within a metal building, is the
building properly grounded?
As a result, all installation requirements outlined
a b o v e must be complied with. Additionally, the
Note. When a water recirculating pump is used, the in-
coming water hose and torch water hose should not be connected
metal building must be bonded to several ground rods
to the water solenoid valve on the side of the welder. Instead, the
placed around the periphery of the building. For
torch water hose should connect directly to the recirculator. The
best results the earth around these ground rods must
cooling water will then circulate continuously and the recircula-
be treated (para 2-4.c.(2).
ting pump will not have to work against a closed valve when the
(7) Check list of high frequency stabilized arc
operator is not welding,
e. Water Connections. Connect water fittings and
welding equipment installation.
pipes to the lower fittings on the side panel of the
(a) Has the equipment been located so that
ground leads can be kept short (8 feet or less)?
nections using a water strainer.
(b) Are the power leads serving the unit in
Warning: Use a plastic or rubber hose be-
rigid metallic conduit?
tween the connector assembly and water drain.
(c) If rigid metallic conduit is not used, is
f. Gas Connections. Connect gas fittings and pipes
equivalent copper braid sleeving, or lead covered
to the upper fittings on side panel of the machine.
cable used?
Note. Flexible helically wrapped metallic conduit (BX)
g. Power Connection. The welding machine can
is not suitable.
(d) Is there good electrical contact between
operate from either 230 vac or 460 vac by correctly
power conduit and welder case?
(e) Is there good electrical contact between
Connect power to L1 and L2 through a fuse box