ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
MRI LED lights dimmer control replacement - wow!
by Potseal. 01/19/18 08:52 PM
VDE 0100 to introduce AFCIs
by sparky. 01/19/18 08:03 PM
Video: Inventor of the GFCI self-testing shocks
by Bill Addiss. 01/17/18 11:11 PM
FPE in Germany
by HotLine1. 01/17/18 07:07 PM
Fujifilm Recalls Power Adapter Wall Plugs
by Admin. 01/16/18 07:04 PM
New in the Gallery:
Housebilding DIY wiring
SE cable question
Who's Online Now
0 registered members (), 6 guests, and 13 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
2 OT for 200A residential service? #101568
12/30/01 05:09 PM
12/30/01 05:09 PM
S
Sandro  Offline OP
Member
Joined: Dec 2001
Posts: 444
Stoney Creek, ON, Canada
Is this still permissible in the CEC? Or must we continue using 3 ot?

Tools for Electricians:
Re: 2 OT for 200A residential service? #101569
01/02/02 10:45 AM
01/02/02 10:45 AM
B
bill woods  Offline
Member
Joined: Nov 2001
Posts: 45
According to CEC Table 2, 2/0 is permissible for a 200A residential service. Local authorities still have the final say though.

Re: 2 OT for 200A residential service? #101570
01/03/02 03:20 PM
01/03/02 03:20 PM
T
Tony Moscioni  Offline
Moderator
Joined: May 2001
Posts: 144
CANADA
For 3-wire 120/240 and 120/208 V residential services or subservices, the allowable ampacity for sizes No.6 and No.2/0 AWG shall be 60A and 200A respectively.

In this case, the 5% adjustment of Rule 8-106(1)cannot be applied.

Tony Moscioni
© Electrical Safety Authority - 2002

Re: 2 OT for 200A residential service? #101571
01/03/02 07:23 PM
01/03/02 07:23 PM
S
Sandro  Offline OP
Member
Joined: Dec 2001
Posts: 444
Stoney Creek, ON, Canada
Tony... thanks for confirming this. I have a further question. Can I use 2 runs of 2ot (per phase) for parallel runs on a 400A residential service?

Re: 2 OT for 200A residential service? #101572
01/03/02 09:34 PM
01/03/02 09:34 PM
T
Tony Moscioni  Offline
Moderator
Joined: May 2001
Posts: 144
CANADA
This deviation . . . . 2/0-awg-cu for a 200-amp 120/240-volt residential services(3 copper conductors in a raceway or cable) for R90 / RW90 / T90 Nylon / & MI Cables shall apply for 200-amp residential services....ONLY.

If in your case a 400-amp service was required for a 120/240-volt residential service, then if you were to observe Table #2 - (3 copper conductors in a raceway or cable) for R90 / RW90 / T90 Nylon / & MI Cables, then 500-kcmil would be acceptable as a service entrance conductor.

Rule 8-106 Use of Demand Factors

(1) The size of conductors and switches computed in accordance with this Section shall be the minimum used except that, if the next smaller standard size in common use has an ampacity not more than 5% less than this minimum, the smaller size conductor shall be permitted.

Rationale and Intent for Rule 8-106(1). Switches and conductors are rated in standard sizes, and in some cases the use of conductors and switches with ratings less than the calculated load may be suitable.

We intend that the calculated load, as calculated in accordance with this Section, be the minimum size of conductors and switches. Rarely is the calculated load the same as the standard ratings of switches and conductors. We intend to establish conditions that can be used to accept standard size electrical equipment that is slightly smaller than the calculated load. For example, use 210 A calculated load; 5% of 210 = 10.5 A and 210 – 10.5 = 199.5 A.

Rule 8-106(2)

In any case other than a service calculated in accordance with Rules 8-200 and 8-202, where the design of an installation is based on requirements in excess of those given in this Section, the service and feeder capacities shall be increased accordingly.

Rationale and Intent for Rule 8-106(2).

The CE Code, Part I, is based on minimum requirements and is not intended to limit design. It is important that services and feeders be adequately sized for the actual loads they must carry. We intend that for services, other than those calculated in accordance with Rules 8-200 and 8-202, where the electrical installation is based on requirements in excess of Section 8, the service and feeder capacities be sized to meet the requirements of the actual load, regardless of Section 8 requirements.

Tony Moscioni
© Electrical Safety Authority - 2002


Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Attic Rat
Attic Rat
Bergen Co.,N.J. USA
Posts: 524
Joined: December 2003
Show All Member Profiles 
Top Posters(30 Days)
Admin 20
sparky 16
Potseal 15
Popular Topics(Views)
243,561 Are you busy
180,362 Re: Forum
170,840 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.049s Queries: 14 (0.031s) Memory: 0.9669 MB (Peak: 1.1066 MB) Zlib enabled. Server Time: 2018-01-20 08:57:03 UTC