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fw:Calculating diy ugh
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To: aquatic-plants at actwin_com
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Subject: fw:Calculating diy ugh
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From: "shaji (s.) bhaskar" <bhaskar at bnr_ca>
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Date: Sun, 3 Sep 1995 15:01:00 -0400
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X400-Content-Type: P2-1984 (2)
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X400-Received: by mta bnr.ca in /PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/; Relayed; Sun, 3 Sep 1995 15:02:46 -0400
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Here's a forwarded message.
-Shaji
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Shaji Bhaskar, bhaskar at bnr_ca
BNR, 35 Davis Dr., RTP, NC 27709, USA (919) 991 7125
---forwarded message---->
Sep 03 10:46:00 1995
From: dallenb at feldspar_com
Subject: Calculating diy ugh
Underground heating cable
power chart
power = v*v/r resistance = v*v/p
watts volt v*v Res Amp
25 6 36 1.440 4.167
25 12 144 5.760 2.083
25 24 576 23.040 1.042
50 6 36 0.720 8.333
50 12 144 2.880 4.167
50 24 576 11.520 2.083
75 6 36 0.480 12.500
75 12 144 1.920 6.250
75 24 576 7.680 3.125
100 6 36 0.360 16.667
100 12 144 1.440 8.333
100 24 576 5.760 4.167
length of cable require in meters
based on 1 to 2 watts per 10 litre of water
5 7 9 11 13 15 17 20
Watts Required resistance per meter
25 0.288 0.206 0.160 0.131 0.111 0.096 0.085 0.072
25 1.152 0.823 0.640 0.524 0.443 0.384 0.339 0.288
25 4.608 3.291 2.560 2.095 1.772 1.536 1.355 1.152
50 0.144 0.103 0.080 0.065 0.055 0.048 0.042 0.036
50 0.576 0.411 0.320 0.262 0.222 0.192 0.169 0.144
50 2.304 1.646 1.280 1.047 0.886 0.768 0.678 0.576
75 0.096 0.069 0.053 0.044 0.037 0.032 0.028 0.024
75 0.384 0.274 0.213 0.175 0.148 0.128 0.113 0.096
75 1.536 1.097 0.853 0.698 0.591 0.512 0.452 0.384
100 0.072 0.051 0.040 0.033 0.028 0.024 0.021 0.018
100 0.288 0.206 0.160 0.131 0.111 0.096 0.085 0.072
100 1.15 0.823 0.640 0.524 0.443 0.384 0.34 0.288
wire size
Gauge Dia-mm R/mtr Res/1000'
26 0.405 0.137 41.6
27 0.361 0.172 52.5
28 0.321 0.217 66.2
29 0.286 0.274 83.4
30 0.255 0.345 105.2
31 0.227 0.436 132.7
32 0.202 0.516 157.3
33 0.180 0.693 211.0
34 0.160 0.873 266.0
Hammond Transformers as listed 1994
(available at most electrical suppliers)
volts 2amps 3amps 4amps 5amps 6amps 8amps 10amps
6.3 166L6 166N6 165Q6 165S6
($13) ($17) ($22) ($29)
12.6 166L12 166N12 166Q12 165R12 165S12
($16) ($25) ($30) ($26) ($37)
25 166L25 165M25 165N24 165P25 165S25
($12) ($25) $(27) ($36) ($50)
These prices are in Canadian $ from Electrosonic catalog
they sould be used as a guide only. The gaps could be filled
with other manufactures.
example.
tank 255 ltr length = 122cm
hight = 46cm width = 44cm
gravel 10cm volume 122x36x44 = 193ltr
length of cable = 122x(44/6)+(50x2) = 10.9 metres.
Wattage required 192/10 = 19.3 at 1 watt/10ltr or 38.6 watts at 2w/10ltr
lower wattage(20):
under 11 mtr length of cable 2 options .131 or .524 ohms/mtr. I would choose
the highest voltage possible. 12 volts at .524 ohm/mtr at 2 amps, now look
at wire size available for .524; Nearest is .516 ohm/mtr and wire size of 32
gauge. Transformer is 166N12 rated at 4 amps.(actual 27.9 watts)
higher wattage(40):
11 metre length .262 ohms/mtr at 12 volts 4 amps. wire size .274 29 gauge
wire, transformer 166Q12 6 amps. (actual 52 watts)
Doug Bardell
Garson, Ont, Ca.