who does the load calculation?

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mtnelectrical

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Essex, New Jersey
GC is renovating a building 18 apartm. all electrical would be new with new panel, new circuits in kitchen, etc. Went to get permit for new service too and inspector told me I would need the load calc. from an architect. and he said when it is 2 familiy or less we could do it but not for a multidwelling. Is that a local thing or you guys face the same problem?
 
It's a normal part of non-resdiential work, especially if the POCO requires it for their service equipment.
 
hardworkingstiff said:
Why would he think an architect would know more than a licensed contractor about load calculations?

IMO, this is wrong. You (contractor) should be able to supply the load calculations.
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I agree I do all the calc's on my jobs.
 
hardworkingstiff said:
mtnelectrical said:
...inspector told me I would need the load calc. from an architect....
Why would he think an architect would know more than a licensed contractor about load calculations?

IMO, this is wrong. You (contractor) should be able to supply the load calculations.
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Perhaps it is a state law. For example, in Utah you must be a registered design professional (PE, Architect, etc) to desgin certain components of buildings.
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Here in New Jersey it is a state law, you must be a registered design professional, PE, or Architect, they will require a plan set for review, sealed by PE, or Architect, we use a PE for these jobs, i would not want to take on the liability for the design, my insurance would sky rocket, if i did design work, most contractors general liability insurances do not cover design.
 
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Mtn,

Ditto to what Satcom mentioned. I believe what the inspector was trying to infer was that a sealed set of drawings should be submitted showing load calculations performed by a qualified person (and that doesn't mean that you are not educationally qualified but that you are not legally qualified) . The architect would either have to be a PE in addition to being an architect or he would have to hire someone to do the calculations and indicate that on his drawings. The same reasoning applies to commercial services. We, as electrical contractors, are not qualified to size commercial services (of any size) here in NJ.

Phil,
Gold Star Electric
 
On a somewhat similiar note... I'm wiring a new log cabin with a 200A underground feed to the BP. The POCO transformer sits about 50 feet from the house. The other day the POCO showed up to install the transformer and since I was there, I walked over to "shoot the bull" with the linemen. Out of curiosity I read the labeling on the transformer and it was only 24KVA!. The POCO knows that the house has (and needs) a 200A service, so I didn't question them about the sizing of the transformer. I know that they play by their own rules, but has anyone else had any similiar experience?
 
hillbilly said:
On a somewhat similiar note... I'm wiring a new log cabin with a 200A underground feed to the BP. The POCO transformer sits about 50 feet from the house. The other day the POCO showed up to install the transformer and since I was there, I walked over to "shoot the bull" with the linemen. Out of curiosity I read the labeling on the transformer and it was only 24KVA!. The POCO knows that the house has (and needs) a 200A service, so I didn't question them about the sizing of the transformer. I know that they play by their own rules, but has anyone else had any similiar experience?
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The utilities use different demand/diversity factors when sizing equipment. The calculated load as determined by Article 220 is slightly to excessively conservative. For example, my home is supplied by a 15kW transformer that is also supplying 3 other homes. Yet Article 220 probably would require a minimum of a 100-ampere service to each home. Mine has a 200A with electric heat, water heater, range and pool. I have not had a power problem to date.
 
goldstar said:
Mtn,

Ditto to what Satcom mentioned. I believe what the inspector was trying to infer was that a sealed set of drawings should be submitted showing load calculations performed by a qualified person (and that doesn't mean that you are not educationally qualified but that you are not legally qualified) . The architect would either have to be a PE in addition to being an architect or he would have to hire someone to do the calculations and indicate that on his drawings. The same reasoning applies to commercial services. We, as electrical contractors, are not qualified to size commercial services (of any size) here in NJ.

Phil,
Gold Star Electric
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Ok, but what about when we are adding more load to an existing building? Let's say an small store maybe 20'x40' want to install central air of 3 ton, You get a PE to do the calcs. too? Does the building dptm ask all the time for this?Sorry to make dumb questions, I do not have to much experience in this legal part of the business.
BTW, They asked me, what size transf was there in the pole. Am I suppoused to know by sight the size of this?
 
mtnelectrical said:
Ok, but what about when we are adding more load to an existing building? Let's say an small store maybe 20'x40' want to install central air of 3 ton, You get a PE to do the calcs. too? Does the building dptm ask all the time for this?Sorry to make dumb questions, I do not have to much experience in this legal part of the business.
BTW, They asked me, what size transf was there in the pole. Am I suppoused to know by sight the size of this?
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I practice in New Mexico, and the law says a commercial building with an occupant load of 10 or more must have a design professional prepare all plans for new construction or alteration. If the occupant load is over 50/or permitted value greater than $400,000 it must have architects and all engineering disciplines with separate seals. This is a calculated occupant load, not the number of employees or something like that.

Other jurisdictions will have other rules.

Jim T
 
Mtn,

I don't believe the onus should be on you to get a PE to size the service. It should be up to the store owner unless your company generally provides that service, in which case, you should be charging for that. As far as the xfmr size goes, you would have to contact the POCO to find out the size. Many of the townships in our area are now asking what the short circuit rating of the Xfmr is. Many of the older main breaker panels only had a 10k short circuit rating but most now are being manufactured with a 22k rating. So, when you contact the POCO make sure you ask about the short circuit rating because if he wants to know the size of the xfmr, I'm sure the inspector will ask you about the short circuit rating also.

BTW, do you belong to the NJECA and/or a local contractors' association ? If so, at some point in time you may attend a CEU class on fuses presented by Bussman Fuses and given by Al Cox. He showed some interesting videos on what happens when services exceed the short circuit ratings of breaker panels. Big flash - lots of damage.

Phil
 
On the OP: Anything over 200 amps around here requires a Engineer's stamp.

On the sizing of POCO equipment: I haven't even seen a common pattern in the way various POCO's operate. Some places, I've seen 25KVA supporting two houses with 150A services, other places I've seen 25KVA supporting 6 units of a condo. It's hard to tell if they all even read from the same book. :)
 
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