THE BROWN-DUVEL MOISTURE TESTER 
37 
partments, amperes required, 13.8. A size 14 wire is large enough 
to carry the current if it is "other than rubber insulated," but 30 
feet of this wire will give a line drop in voltage of 1 per cent so 
that it would not be desirable to use that size. Size 12 requires 48 
feet to give a 1 per cent drop, hence, would be the size to select. 
Should it be desired to decrease further the drop in voltage, any 
larger size wire could be used, as for instance a No. 6 wire, and the 
drop determined by dividing 40 by the length for 1 per cent drop, 
or 193, giving practically 0.2 per cent drop. 
It is important that all wiring for electrically -heated moisture 
machines be done by a competent electrician. Even then he should 
be impressed with the fact that the voltage at the machine must be 
kept as nearly constant as possible, whether one compartment or 
several dozen are operating. 
Table 11. — Wiring for electrically heated moisture machines 
Amperes allowed, insulation other than rubber 
Amperes allowed, rubber covered '. 
of wire B. & S. gauge 
14 
12 
10 
8 
6 
16 
12 
23 
17 
82 
24 
46 
33 
65 
46 
Amperes 
required 
by 
machine 
Length of circuit for 1 per cent drop 
On 110-volt circuit: 
2 compartments 
4 compartments 
6 compartments 
On 220-volt circuit: 
2 compartments 
4 compartments 
6 compartments 
9.2 
18.4 
27.6 
4.6 
9.2 
13.8 
Feet 
Feet 
Feet 
Feet 
Feet 
22 
36 
57 
91 
144 
18 
28 
45 
72 
19 
30 
48 
9f) 
144 
228 
45 
72 
114 
182 
290 
30 
48 
76 
121 
193 
Feet 
182 
91 
Values in italic figures refer to "insulation other than rubber"; all other values refer to either method of 
insulation. 
EFFECT OF LOW VOLTAGE ON MOISTURE-TEST RESULTS 
Investigations have shown that there is a wide variation in the 
electric pressure available at various markets. Studies were made 
to determine what influence that fluctuation or drop in voltage has 
on the heating time in making moisture tests with testers equipped 
with electric heaters and its effect on the moisture-test result. Ex- 
periments to determine the influence of a drop in voltage on the 
heating time were made at the electric measurement division of 
the United States Bureau of Standards. The results obtained from 
these tests are given in Table 12. The table shows the maximum, 
minimum, average, and range in results of all series of tests on both 
the electric testers and the gas-heated testers. _ The table also shows 
the minus or plus variations, in time of heating and percentage of 
moisture obtained for all voltage series on the electric tester, from 
the same series of samples when tested on the standard gas-heated 
tester. 
