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Drilling and cutting #168135 08/27/07 06:21 PM
Joined: Jul 2007
Posts: 265
wire_twister Offline OP
I have a job for a church, going to install a new 400 amp 3 phase service. The church people want it underground, problem is the church foundation is built from granite blocks 10 inches thick. Anybody ever tangle with this much rock? How did you get through it? Did you do it without the use of explosives?? any advice would be appreciated.


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Re: Drilling and cutting [Re: wire_twister] #168136 08/27/07 06:54 PM
Joined: Apr 2002
Posts: 7,237
HotLine1 Offline
Look for a core drilling company in your area. May be 'Concrete Cutting' or 'Core Drilling'.
Unless you have the right equipment you should not do it yourself. Get an estimate & include it in your pricing.

Re: Drilling and cutting [Re: HotLine1] #168139 08/27/07 08:04 PM
Joined: Mar 2004
Posts: 782
BigB Offline
Also, the coring and sawing companies do not take any responsibility for hitting anything like water/sewer lines etc, so make sure you locate them first, and possibly write a disclaimer into your own bid.

Re: Drilling and cutting [Re: BigB] #168144 08/27/07 09:03 PM
Joined: Apr 2002
Posts: 7,237
HotLine1 Offline
Pro's around here (NJ) use ground penetrating radar type equipment to locate critical items. Post tension cable/rebar, conduit, pipes, etc.
The old addage...ya get what ya pay for.
Liability Insurance Certificates are a good thing to get from any subs that you hire, it's also nice to tell your clients that they should ask for proof of insurance.

Re: Drilling and cutting [Re: HotLine1] #168145 08/27/07 10:39 PM
Joined: Jul 2007
Posts: 265
wire_twister Offline OP
this is a horizontal hole thru a foundation wall about 20 inches below grade on the outside, which is right at grade level on the inside. has to be big enough to get 2 two inch conduits thru, doesent have to be prety the church people say they will patch any over cut with morter.


Life is tough, Life is tougher when you are stupid
Re: Drilling and cutting [Re: wire_twister] #168153 08/28/07 06:48 AM
Joined: Jan 2005
Posts: 74
Tom H Offline
Absolutely hire a concrete cutting company, similar situation, but for building interconnects, gave me a cost per half day, figured 2 whole days in my bid. Got job, they came out, had 4 - 3"x14" deep holes, 2 in each building done in a day. little messy cause they use water core bits, but much faster than I could have done.

Pay a professional to do a professionals job.

Re: Drilling and cutting [Re: Tom H] #168192 08/28/07 07:47 PM
Joined: May 2007
Posts: 169
ChicoC10 Offline
My former employer attempted his own core drilling on one of his first jobs. To make a long story short, far short of being done he had broken his own toe and had the drill come loose, swing around and hit his father in-law square in the jaw. Knocked him cold and broke his jaw. This is not an incompetent man mind you. He was just out of his element and under a lot of pressure.

He happened to run into a the owner of the company doing the core drilling for the plumbers (I think) the next day and found out he could get the rest of it done for about what he'd rented the equipment for in the first place.

Hire the pro.

If he's good he might know something about your type of foundation and the the liabilities or lack therof you might face with making a hole in it.


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